Pharmacia & Upjohn AB v CSL Limited
[2000] APO 58
•15 September 2000
OFFICIAL NOTICE
DECISION OF A DELEGATE OF THE COMMISSIONER OF PATENTS
Application : No. 682274 in the name of Pharmacia & Upjohn AB
Title: Filtration
Action: Opposition under section 59 by CSL limited
Decision: Issued .
Abstract
Opposition succeeds and patent application is refused.
While the claims are novel based on the prior art raised by the opponent, none of the claims involve an inventive step in light of the common general knowledge alone or in combination with a particular US patent specification. In trying to improve viral filtration, the skilled worker would be directly led to try different ways of improving protein recovery by altering parameters known to affect the recovery of protein. This routine optimisation would include increasing the salt concentration within the range claimed for ultrafiltration membranes. Further, because dedicated viral filters only differ in fine structure to ultrafiltration membranes, the principles involved in ultrafiltration could be extrapolated to the new filters. Therefore, it would also be routine for a skilled worker using dedicated viral filters to increase salt to within the range claimed to try to improve viral filtration.
PATENTS ACT 1990
DECISION OF A DELEGATE OF THE COMMISSIONER OF PATENTS
Re:Patent Application No. 682274 by Pharmacia & Upjohn AB and Opposition under section 59 by CSL Limited
BACKGROUND
Australian application 682274 was filed under the provisions of the PCT on 25 June 1995 by Pharmacia AB. It claimed priority from two Swedish basic applications, 9402254-8 and 9500724-1, filed on 23 June 1994 and 24 February 1995 respectively. A change of applicant name to Pharmacia & Upjohn AB (Pharmacia) was subsequently made under the PCT rules and recorded in Australia on 4 November 1996.
The Australian application was advertised accepted on 25 September 1997 and on 31 December 1997, a notice of opposition was filed by CSL Limited (CSL). Evidence was completed on 16 November 1999 and the matter was set for hearing in Melbourne on 21 February 2000.
Amendments were proposed to the accepted specification on 31 March 1999 and these were subsequently advertised allowed on 7 October 1999. The hearing was therefore based on the specification as amended after acceptance.
The applicant was represented by Mr John Slattery patent attorney of Davies Collison Cave, Melbourne and the opponent was represented by Drs Jenny Petering and Bill Pickering, patent attorneys of FB Rice & Co, Melbourne. Also attending the hearing were John Cox and Peter Turvey from the opponent company.
SPECIFICATION
The specification discloses and claims a method for preventing viral contamination of blood macromolecular products (such as gammaglobulin, albumin and factor IX) which are intended for medical use in human beings.
A number of prior art methods for virus removal were discussed. The closest prior art method to the current invention involved passing biological fluid containing a pharmaceutical product through an ultrafiltration membrane. The membrane retained the virus but permitted passage of the pharmaceutical product. The specification discussed two prior patent specifications (US 4, 473,494 and EP 307373). Both patent specifications described a method where the concentration of salt used in the virus filtration step was below 0.1M.
According to the specification, there was a need for a more effective virus-reducing method. The invention achieved this by increasing the salt content of the aqueous solution to the range 0.2M to 2M during virus filtration. The higher salt concentration achieved a macromolecule yield in excess of about 90% in the virus-filtering stage while, at the same time, reduced the:
residence time and the liquid volumes when virus-filtering solutions that contain macromolecules;
filter area required to effectively virus-filter solutions that contain macromolecules;
polymerization obtained on the virus filter surface, so as to enable the rate of flow to be increased and the process time to be decreased.
The specification suggested that this was surprising because it had previously been thought in virus filtration that only the protein concentration, rate of flow and pH had any effect on the filtration process.
The specification as amended after acceptance contains 11 claims only one of which (claim 1) is independent. These claims are as follows:
A filtration method for removing at least one virus selected from the group comprising of hepatitis A, polio virus or parvo virus from an aqueous solution comprising at least one macromoleule, comprising virus-filtering the aqueous solution containing at least one macromolecule, wherein the total salt content of the aqueous solution is within the range of 0.2M to 2.0M.
A method according to claim 1, characterised in that the total salt content of the solution lies within the range of from 0.6 up to 2.0M.
A method according to claim 1 or claim 2, characterised in that the salt is selected from the group consisting of sodium chloride, potassium chloride, sodium acetate, and sodium citrate and combinations thereof.
A method according to any of the previous claims, characterised in that the macromolecule is selected from the group consisting of proteins, polysaccharides and polypeptides and combinations thereof.
A method according to claim 4, characterised in that the macromolecule is factor IX.
A method according to claim 4, characterised in that the macromolecule is gammaglobulin.
A method according to claim 4, characterised in that the macromolecule is albumin.
A method according to claim 4, characterised in that the macromolecule is antithrombin III.
A method according to claim 4, characterised in that the macromolecule is a deletion derivative of recombinant factor VIII.
10) A method according to any one of the previous claims, characterised in that the virus-filtering process is carried out in accordance with the "dead-end" filtering technique.
11) A method according to any one of the previous claims, characterised in that the virus-filtering process reduces the content of non-enveloped viruses by at least 4 logs.
CONSTRUCTION OF CLAIM 1
A key difference between the parties was in their construction of the term “virus-filtering” in claim 1. The opponent argued that the term should be broadly construed and encompass any means of filtering a virus (including techniques such as ultrafiltration). The applicant argued that the term should be narrowly construed and only include filtering means which involve a specialised (or dedicated) virus filter.
I note that the development of dedicated virus filters was a significant advance in the art. The removal of viruses by filtration had apparently been known for decades before the priority date of the opposed specification. However, most of this prior art (including the admitted prior art) involved the use of ultrafiltration membranes rather than dedicated virus filters. Ultrafiltration membranes are produced using a casting technique which results in a very dense, porous membrane layer, supported underneath by a very open matrix. According to the opponent, this means that the membrane has a highly asymmetric structure with a broad pore size distribution. Such filters may contain some large pores through which high molecular weights can pass, including virus particles. As a result, the ability of the membranes to retain virus particles was unpredictable.
To resolve this problem, dedicated virus filters were developed. These have a well-characterised nano pore size membrane, supported underneath with a homogenous filter membrane of uniform micro pore size and the membrane is integrity tested by the manufacturer to prove pore size distribution mechanism of the filtered membrane. These filters are more effective in ensuring that all virus are retained on the membrane and hence removed from the aqueous solution.
Both the opponent’s Australian expert witnesses acknowledged the development of dedicated virus filters. However, in absence of a qualification of the term “virus-filtering” in the specification, they interpreted the term broadly to include any type of filtering [see, for example, evidence in support, Professor Gray (paragraph 41); and evidence in reply Dr Johnston (paragraph 6)]. I accept the opponent’s interpretation as being the plain meaning of the term at the relevant time in Australia. The techniques for “virus-filtering” existed well before the development of dedicated virus filters and included filtering using other types of filters. It seems unlikely to me that the broad plain meaning of that term would have been narrowed with the introduction of the dedicated filters because firstly, the new filters had only been recently developed and secondly, they were not always necessary in viral filtration (for example, in preparing virus vaccines, a small loss of virus was acceptable). I also note that the applicant did not provide an Australian expert to suggest that the plain meaning in Australia at the relevant time was different to that suggested by the opponent.
The applicant argued, using Décor CorporationPty Ltd and Another v Dart IndustriesInc 13 IPR 385, that the meaning of the term had to be considered in light of the specification as a whole. According to the applicant, the term “virus-filtering” was clearly used in a narrow sense in the specification particularly in view of a sentence on page 8 of the specification which stated:
“Virus filters are known in the art and are supplied by Millipore from Massachusetts, USA amd Asahi Chemical Industry Co., Ltd from Japan among others.”
However, the sentence relied on by the applicant was merely in the context of (preferred) types of filters to be used and where they could be obtained. In my view, using this sentence to narrow the plain meaning of the term “virus filtering” in the claim would be importing “glosses drawn from other parts of the specification” [as per Décor v Dart (supra)].
In addition, the specification as a whole does not highlight the importance of using dedicated virus filters. For example, in distinguishing the prior art (which involved ultrafiltration membranes), the specification only discussed differences in salt concentrations and not filter types. The term “virus-filtering” was used in the discussions of EP 307373 to refer to an ultrafiltration step. It seems to me that if the applicant intended the word “virus-filtering” to have a narrow meaning, they should have had a clear definition in the specification. This is consistent with the principles outlined in Mineral Separation North America Corporation v Noranda Mines (1952) 69 RPC 81 (at p 93):
"If he has put something in the earlier part of the specification which plainly tells the reader that for the purpose of the specification he is using a particular word with a meaning which he sets out, then the reader knows that when he comes to the claims he must read that word as having that meaning. But this is an awkward method of drafting ... and it is in all cases incumbent on a patentee who chooses to adopt this method to make his intention plain to those who read the specification."
I find that, as currently drafted, the term “virus-filtering” should be broadly construed in light of its plain meaning. It therefore encompasses any means of filtering a virus (including techniques such as ultrafiltration).
The other phrase in claim 1 which was specifically discussed at the hearing was “for removing at least one virus selected from the group comprising of hepatitis A, polio virus or parvo virus”. Both parties agreed that this phrase merely meant that the filtration method was capable of removing one of the listed types of virus and that viral particles may not necessarily be present in the solution to be filtered. I accept this interpretation noting that is consistent with
the non-limiting way that the term “for” has traditionally been construed by the courts in Australia.
The parties also agreed that the term “removing” in the phrase discussed above did not require the method to be capable of 100% removal of the virus. Thus, a method which achieved a reasonable level of removal would also fall within the scope of the claims. I agree with this interpretation noting that claim 11, which is dependent on claim 1, specifies a certain degree of removal (a reduction of at least 4 logs). This means that that complete removal could not have been contemplated in claim 1.
DECISION
Novelty
At the hearing, the opponent relied on 2 citations under the ground of novelty:
Melling, Downs and Brewer (1973) The effects of salts and pH on the ultrafiltration of enzymes, J. Appl. Chem. Biotechnol. 23:166-167 [exhibit WJP-11] - Melling;
US patent specification 5,076,933 by Glenn et al [exhibit WJP-16]
The first citation reported a study on the effects of salt on the ultrafiltration of an enzyme, ß-lactamase, produced by Staphloccus aureus. The applicant argued that the citation used an ultrafiltration membrane rather than a dedicated virus filter. However, while this is true, I have found above that the claims are not limited to the dedicated viral filters. Ultrafiltration membranes are acknowledged to be capable of removing viruses to some extent. The claims are not limited to a particular level of removal of viruses nor to a particular type of filter and hence a method using ultrafiltration membranes could potentially deprive the claims of their novelty.
The opponent argued that the citation disclosed concentrations of salt within the range claimed in the current specification (0.2M, 0.4M and 0.8M ammonium sulphate and 0.8M potassium chloride) and showed that salt concentration could affect the recovery of protein. The citation taught that 0.4M ammonium sulphate gave virtually 100% throughput of ß-lactamase at pH 6.0. According to the opponent, this provides clear and unmistakable directions to use a salt concentration of around 0.4M in order to improve filtration efficiency.
In my view, the opponent has been a tad selective in their analysis of the citation and has not considered it as a whole. The citation not only describes the effect of ammonium sulphate on the purification of ß-lactamase from Staphloccus aureus, it also studies the effect of KCl on the recovery of ß-lactamase as well as the effect of NaCl concentration on the recovery of the enzyme ß-N-acetylglucosaminidase from Bacillus subtilis. I have summarised the results from the paper in the following table:
| Enzyme | Low (NH4)2SO4 | High (NH4)2SO4 | Low KCl/NaCl | High KCl/Nacl |
| ß-lactamase | 10% recovery in zero concentration of salt | 100% recovery at 0.4M at pH 6.0; | 75% recovery at 0.07M | 17% recovery at 0.8M |
| ß-N-acetylglucosaminidase | Not done | Not done | 20% recovery in zero concentration of salt | 9% recovery at 0.6M, 65% recovery at 4M |
It is clear from this table that a range of factors including pH, salt concentration and even the protein itself, can have a marked effect on the recovery of a protein after filtration. From the citation as a whole, it is apparent that filtration using a salt concentration within the range of the claims (ie 0.2M to 2.0M) will not always generate higher yields. In fact, with KCl , there was a low recovery of both enzymes in the range defined in the current claims which would teach away from the current invention.
In General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd ( 1972) RPC 457, the court noted that if a prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee's claim, but would be at least be as likely to be carried out in a way that would not do so, the patentee's claim will not be anticipated. Given the large variation in recovery of protein using different salt concentrations, the skilled worker might consider varying both pH and salt concentration to improve protein recovery but would not have “clear and unmistakable directions” to choose a particular salt concentration within the claimed range to improve protein yields. Since this feature is in all the claims, the citation does not deprive any of the claims of their novelty because, as noted in General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd (supra):
"To anticipate the patentee’s claim the prior publication must contain clear and unmistakable directions to do what the patentee claims to have invented….A signpost, however clear, upon the road to the patentee’s invention will not suffice. The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentee”.
The second citation discloses the removal of viruses from biological pharmaceutical solutions including monoclonal antibodies or albumin using ultra-filtration membranes (such membranes, as noted above, being encompassed within the scope of the claims). The description shows that viruses as small as 0.016 microns can be removed, which includes the hepatitis A, polio or parvo viruses defined in claim 1. The citation also discloses filtration using salt concentration of less than 0.5M. The opponent argued that this overlaps with the claimed salt range of claim 1 depriving this claim of its novelty.
The applicant argued that although the citation broadly disclosed the use of salt concentrations up to 0.5M, it does not explicitly direct the skilled worker to use higher concentrations (ie greater than 0.2M) within the broader range. The opponent acknowledged this but counter-argued that the removal of viruses in the examples of the current specification was the same in all the salt concentrations tested (both above and below 0.2M salt). According to the opponent, there was no selective advantage to using the higher salt concentrations and therefore the broad disclosure of the citation was sufficient to deprive the claims of their novelty.
In my view, while the removal of viruses may have been the same, the recovery of protein in the filtrate was clearly better in the examples where a salt concentration greater than 0.2M salt was used (see examples 1 and 2 of the opposed specification). Hence, there is a clear advantage in using higher salt compared with lower salt concentrations. The citation does not teach a skilled worker to use the higher salt concentrations and there is no evidence before me to indicate that the skilled worker reading the citation would inevitably choose the higher concentrations. As a result, the skilled worker in following the directions of the citation would be as least as likely to choose a lower salt concentration compared with a higher one. Thus, there are not clear and unmistakable directions to choose the higher salt concentrations and therefore the claims are not anticipated by the second citation.
In conclusion, neither of the citations relied on by the opponent at the hearing deprive any of the claims of their novelty.
Inventive Step
The opponent’s experts declared that, inter alia, it was common general knowledge in Australia at the priority date that:
The removal of viruses from solutions using filtration membranes was well known before the priority date (see Gray's declaration, paragraph 26 evidence in support);
Retention or passage of viruses through filters depends on a range of factors including presence of salts. High concentrations of salt were known to improve virus solvation making the virus less likely to clog membrane pores (see Gray's declaration paragraphs 28, 47, evidence in support);
Various parameters including salt concentration were well-known to influence membrane filtration processes and it was routine to manipulate those parameters in order to optimise protein recovery (see Gray's declaration paragraph 57, evidence in support; first Johnstone declaration paragraphs 51, 53);
Salt reduces electrostatic interaction between molecules and therefore increases solubility of macromolecules in solution (see Gray's declaration paragraph 23, evidence in support);
Under some conditions, salt may improve the transmission of proteins through membrane filters (See Gray declaration paragraph 48, evidence in support);
Dedicated viral filters were well known and commercially available before the priority date (see Gray's declaration paragraph 33, evidence in support).
According to the opponent, given the common general knowledge above, the skilled worker would routinely use the process of membrane filtration to remove viruses from an aqueous solution containing at least one macromolecule and vary the salt concentration in order to optimise the process. The opponent argued that this routine optimisation would include increasing the salt concentration within the range claimed and as a consequence, the opponent argued that all of the claims lacked an inventive step.
In support of their assertions as to what constituted the common general knowledge, the opponent noted there were many citations in the 1970s relating to the removal or concentration of viruses from sewerage by membrane filtration (point 1 above) and a range of documents relating to the use of dedicated virus filters (point 6 above). At the hearing, the opponent also referred to the following citations in relation to points 2-5 above:
A.Melling (cited above under the ground of novelty) (in support of points 3, 5);
B.Wallis et al (1979) Concentration of viruses from water by membrane chromatography, Ann. Rev. Microbiol. 33: 413-37 (in support of 1-3).
C.A.V. Bild’dyukevich, E. G Ostrovskii and F. N. Kaputskii “Ultrafiltration of Model Solutions of High Molecular Weight Compounds. Influence of the Ionic Strength on the Ultrafiltration of Protein Solutions” Kolloidnyi Zhurnal, 51, no.2, pp 349-353, March- April 1989 (in support of points 2 and 5); and
D.T.W. Mix (1974) “The Physical Chemistry of Membrane-Virus Interactions” Developments in Industrial Microbiology 15 136-142 ( in support of points 1-3);
The opponent did not argue that any of citations A-D (by themselves) were part of the common general knowledge nor is this self-evident that this is the case. However, the citations indicate the type of approaches being used by skilled workers in the field of membrane filtration and thereby provide some documentary support for the statutory declarations made by the opponent's experts.
The applicant did not provide any Australian experts to counter the opponent's assertions of the common general knowledge. In fact, the applicant did not dispute the common general knowledge outlined above except in relation to whether it was known that salt concentration affected filtration using dedicated virus filters. The applicant argued that while it may have been common general knowledge to vary the salt with ultrafiltration membranes, this was not the case for the dedicated filters. According to the applicant, filtration using dedicated viral filters was significantly different to ultrafiltration and while it may have been routine to alter the salt conditions for an ultrafiltration membrane, this was not the case for a dedicated viral filter. While I noted above that the claims are not currently limited to this type of filter, it is clear from the applicant’s submissions that this type filter is a critical part of their inventive concept and should have been defined in the claims. For this reason, I will consider the issue of inventive step based on both the claims as currently drafted (which includes ultrafiltration membranes) and the claims as if they were limited to dedicated viral filters.
The applicant suggested that ultrafiltration membranes are structurally different than the dedicated viral filters and that it would not be obvious to a person skilled in the art to predict the performance of a dedicated virus filter on the basis of trials with ultrafiltration membranes. I note that while there was some implication in evidence in answer that ultrafiltration membranes were hydrophobic compared with hydrophilic dedicated viral filters, this was refuted in evidence in reply [paragraph 12 of Dr Johnstone’s second declaration] and this specific distinction was not argued at the hearing.
As a result, as Professor Gray pointed out in paragraphs 49 and 50 of his evidence in support, the only difference between the dedicated viral filters and the ultrafiltration membranes is in the “fine structure” of the membranes. This means that the difference between the filters is only in the consistency of the pore size rather than any fundamental difference in how the filters work. Hence, the two types of filters appear to work in an analogous way, even if the dedicated viral filter is more predictable and consistent.
It is hard for me to accept that when a new type of filter is introduced, the skilled worker would not apply his knowledge gained from working with earlier filters, if they were analogous. Ultrafiltration membranes had been used (and were the filter of choice) in viral filtration prior to the introduction of the dedicated viral filters. Skilled workers using viral filters were therefore aware of the principles of ultrafiltration. Given that the differences between the ultrafiltration membrane and the dedicated viral filters were only in the fine structure, it would have been obvious to the skilled worker at the priority date of the claim to apply the principles of ultrafiltration to the dedicated viral filters. If parameters such as salt concentration were known to improve protein recovery in ultrafiltration (as the opponent's evidence suggests and the applicant appears to have conceded), it would have been obvious to try manipulating the salt concentration to increase protein recovery in viral filtration using either an ultrafiltration or a dedicated viral filter.
In evidence in answer, the applicant pointed out that the main application for ultrafiltration is concentration and diafiltration (buffer exchange) and a more unusual application is separation of macromolecules from other macromolecules. According to the applicant, a person skilled in the art developing an ultrafiltration step in concentration/diafiltration is not facing the same problems as a skilled worker developing a virus-filtration technique. However, while the main application for ultrafiltration membranes may have been concentration, the only previous work in viral filtration (separating macromolecules from viruses) involved ultrafiltration membranes and the development of viral filters was based on the problems with the ultrafiltration membranes (the inconsistent pore size). In the field of viral filtration, the skilled worker using ultrafiltration membranes was faced with the same problem as the skilled worker using dedicated viral filters.
There was some suggestion in the evidence that it would not be predictable what effect increasing the salt concentration has on transmission of the virus through the filter and that if the skilled worker was faced with the problem of ensuring viral removal, they would not automatically increase salt concentration. While I accept the possibility that viral transmission could have increased with higher salt (given the influence that salt has on filtration), I do not believe this would have prevented the person skilled in the art from routinely increasing the salt concentration. Success does not need to be guarantied to deprive the claims of the inventive step as noted in Beecham Groups Ltd’s (Amoxycillin) Application [1980] RPC 261 (at 290):
“It is clearly established that, for a particular step or process to be obvious…it is not necessary to establish that its success was clearly predictable…it will suffice if it is shown that it would appear to anyone skilled in the art but lacking in inventive capacity that to try the step or process would be worthwhile”
There was no indication in the common general knowledge that transmission of virus was likely to increase with higher salt. Further, from the common general knowledge, it appeared that virus solvation and dispersion was favoured in higher salt concentrations making the virus less likely to clog membrane pores. Consequently, viral filtration was likely to be better in a higher salt concentration and so the skilled worker would be taught towards, and not away, from the solution.
In trying to improve viral filtration, the skilled worker would be directly led to try different ways of improving macromolecule recovery (such as proteins) by altering parameters known to affect recovery. This routine optimisation would include increasing the salt concentration within the range claimed. The skilled worker would have found as a matter of routine that salt concentrations within the claimed range favoured virus filtration. From their knowledge that increasing the salt concentration improved viral solvation, the skilled worker would have a reasonable expectation that increasing salt concentration to within the range claimed would successfully increase filtration efficiency using ultrafiltration membranes. Further, because dedicated viral filters only differ in fine structure to ultrafiltration membranes, the principles involved in ultrafiltration could be extrapolated to the new filters. Therefore, it would also be routine for a skilled worker using dedicated viral filters to increase salt to within the range claimed to try to improve viral filtration. It follows that none of the claims, as currently drafted (which encompass ultrafiltration membranes), or if limited to the dedicated viral filters, are inventive in light of the common general knowledge.
Therefore, in light of the common general knowledge, claim 1 does not involve an inventive step. Further, none of the dependent claims 2-9, 11 contain a feature which adds an inventive step over claim 1 based on the common general knowledge alone:
Claim 2 merely optimises the salt concentration provided in claim 1;
Claim 3 provides a list of salts but it is well known that different types of salts can be used in filtration of proteins including those listed in claim 3;
Claims 4-9 are characterised by the type of macromolecule being filtered. However, the general principle of using high salt in recovering proteins is not inventive. The application of that principle to specific proteins is not inventive;
Claim 11 specifies that the virus-filtering process reduces the content of non-enveloped viruses by at least 4 logs. This is simply stating a desired level of viral removal which the skilled worker would recognise and try to achieve.
As a result, claims 1-9, 11 lack an inventive step over the common general knowledge alone.
The opponent had also submitted that all the claims lack an inventive step in light of the common general knowledge in combination with any one of citations A-D above. However, these additional citations are really only specific examples of what was stated to be common general knowledge above and the arguments provided by the opponent in relation to the specific citations are the same as those already considered above for the common general knowledge alone. Consequently, the additional citations do not add to the inventive step argument and I therefore do not propose to consider these separately.
Claim 10 is characterised by a specific filtering technique (the dead-end filtration technique). The applicant argued that examples 3, 15, 17, 19 and 22 of the opposed specification show that the dead-end filtration technique results in an increased filtration efficiency when high salt concentrations are used (in the order of a 20% increase) compared to the tangential filtration technique. According to the applicant, this was surprising and clearly distinguishes the invention over the prior art.
The opponent did not provide any evidence to establish that the dead-end filtration technique was part of the common general knowledge and I am therefore unable to conclude that this claim lacks an inventive step over the common general knowledge alone. However, this technique was disclosed in one of the citations considered above for novelty:
US patent specification 5,076,933 by Glenn et al [exhibit WJP-16].
As noted above, this citation discloses the removal of viruses from biological pharmaceutical solutions using ultra-filtration membranes. In my view, the skilled worker could (before the earliest priority date of the claims) be reasonably expected to have ascertained, understood and regarded the citation as relevant. It would be reasonable to expect that the skilled worker would search patent specifications because of the commercial importance of the field. The citation faces a similar problem to that of the opposed specification and as a result, would be found and regarded as relevant in a search of the patent literature. There are also no apparent difficulties in understanding the disclosure.
Given the citation, and faced with the problem of separating viruses from macromolecules so that the yield of macromolecules is maximised but viral contamination is minimised, the skilled worker would have routinely applied the same principles of optimising the viral filtration process as they would have in other techniques in viral filtration. The skilled worker would therefore use the new (more reliable) dedicated viral filters to minimise viral contamination and to alter the salt concentration to optimise protein yields. While the skilled worker might be surprised at the extent that salt affects the protein recovery using the dead end filtration technique, they would still be directly led to the same solution of increasing salt concentration (a "one-way street"). Hence the claim is not inventive in light of the common general knowledge when considered together with US patent 5,076,933.
In conclusion, none of the claims (either as drafted or if limited to dedicated viral filters) contain an inventive step in light of the common general knowledge when considered alone or in combination with US patent 5,076,933.
MANNER OF MANUFACTURE
The opponent argued, using Advanced Building Systems Pty Ltd v Ramset Fasteners (Aust) Pty Ltd (1988) 40 IPR 243 and NV Phillips Gloeilampenfabrieken v Mirabella International Pty Ltd (1995) 183 CLR 655 that section 18 of the Patents Act 1990 imposes a requirement for a threshold level of inventiveness for an invention to be a manner of manufacture. The opponent argued that the use of a higher concentration of salt during virus filtration was no more than a new use of an old substance (as per Commissioner of Patents v Microcell Ltd (1959) 102 CLR 232 at p251) and was therefore not patentable subject matter under section 18(1)(a).
While the opponent phrased their argument using the traditional language of manner of manufacture from Microcell, in my view, there is no difference in substance to the type of arguments already raised and considered under the ground of inventive step. Under inventive step, it was argued that adjusting salt concentration was known to optimise viral filtration using ultrafiltration membranes and it was obvious to apply this principle to viral filtration using dedicated viral filters because of the analogous nature of the types of filters. The same argument can simply be rephrased using the language of manner of manufacture. Thus, it was a known property of altering salt concentration to optimise viral filtration using ultrafiltration membranes. The use of salt in viral filtration using dedicated viral filters was simply using salt for a purpose for which its known properties made it suitable.
Having already considered the opponent's arguments under inventive step, I do not propose to consider them again under the ground of manner of manufacture.
CONCLUSION
All the claims are novel in light of the prior art cited by the opponent but none of claims as currently drafted contain an inventive step in light of in light of the common general knowledge when considered alone or in combination with US patent 5,076,933. Further, there would be no inventive step, even if the claims were limited to dedicated viral filters. As a consequence, I am unable to find any patentable subject matter in the specification and therefore, I refuse the patent application.
COSTS
Costs normally follow the event and I see no reason to depart from this in this case. The opponent has been successful in their opposition and consequently I award costs against the applicant.
Karen Ayers
Delegate of the Commissioner of Patents
Patent attorneys for the applicant : Davies Collison Cave, Melbourne
Patent attorneys for the opponent : FB Rice & Co, Melbourne
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