Board of Patent Appeals and Interferences
Patent and Trademark Office (P.T.O.)
*1 EX PARTE NAGESWARARAO MOVVA AND MARIE-FRANCOIS SCHULZ
Appeal No. 92-4086
July 14, 1993
HEARD: April 22, 1993
Application for Patent filed January 28, 1991, Serial No. 07/647,691, which is a continuation of Serial No. 07/144,655 filed January 12, 1988, which is a continuation of Serial No. 06/534,405 filed September 21, 1983, both now abandoned. DNA-Sequences, Recombinant DNA Molecules And Processes For Producing Swine Growth Hormone-Like Polypeptides.
James F. Haley, Jr. et al. for appellants
Supervisory Patent Examiner--Richard A. Schwartz
Before Goldstein, Seidleck and W. Smith
Examiners-in-Chief
W. Smith
Examiner-in-Chief
This is an appeal from the final rejection of claims 3 through 6 and 9 through 16, all the claims pending in the application.
Claims 3 and 9 are illustrative of the subject matter on appeal and read as follows:
3. A recombinant DNA molecule comprising a DNA sequence encoding a polypeptide displaying the biological activity of swine growth hormone, said sequence being selected from the group consisting of:
(a) [recited] DNA inserts
(b) specific variants of the DNA sequence coding for mature swine growth hormone and which code on expression for a polypeptide displaying the biological activity of swine growth hormone; and
(c) DNA sequences which on expression code for a polypeptide also coded for on expression by the codons of any of the foregoing DNA sequences or inserts.
9. A method for producing a polypeptide displaying the biological activity of swine growth hormone comprising the step of culturing a host transformed by a recombinant DNA molecule comprising a DNA sequence encoding said polypeptide operatively linked to an expression control sequence so that the polypeptide is expressed, said DNA sequence encoding a polypeptide displaying the biological activity of swine growth hormone and being selected from the group consisting of:
(a) [recited] DNA inserts
(b) specific variants of the DNA sequence coding for mature swine growth hormone and which code on expression for a polypeptide displaying the biological activity of swine growth hormone; and
(c) DNA sequences which on expression code for a polypeptide also coded for on expression by the codons of any of the foregoing DNA sequences or inserts.
The references relied upon by the examiner are: [FN1]
Mills et al. (Mills), "Studies On The Primary Structure Of Porcine Growth Hormone", Intern. Cong. Ser., Vol. 244, pages 38-41 (1972).
Wilhelmi, "Chemistry Of Growth Hormone", Handbook Of Physiology, Vol. 4, Section 7, Chapter 23, pages 59-78 (1974).
Martial et al. (Martial), "Human Growth Hormone: Complementary DNA Cloning And Expression In Bacteria", Science, Vol. 205, pages 602-606 (1979).
Miller et al. (Miller), "Molecular Cloning Of DNA Complementary To Bovine Growth Hormone mRNA", The Journal Of Biological Chemistry, Vol. 255, No. 16, pages 7521-7524 (1980).
*2 Suggs et al. (Suggs), "Use Of Synthetic Oligonucleotides As Hybridization Probes: Isolation Of Cloned cDNA Sequences For Human B@2 - Microglobulin", Proc. Natl. Acad. Sci., Vol. 76, No. 11, pages 6613-6617 (1981).
Claims 3 through 6 and 9 through 16 stand rejected under 35 U.S.C. § 103 as unpatentable over Miller and Martial in view of Wilhelmi, Mills and Suggs.
We affirm.
BACKGROUND
The claimed invention is directed to recombinant DNA molecules which encode a polypeptide displaying the biological activity of swine growth hormone. In addition, claims are directed to a method of producing a polypeptide displaying the biological activities of swine growth hormone which involves the use of the claimed DNA-sequences.
Among the specific sequences claimed is the DNA insert in [remainder of the paragraph deleted].
The independent claims are not limited to such specific DNA sequences since they also include "DNA sequences which on expression code for a polypeptide also coded for on expression by the codons of any of the foregoing DNA sequences or inserts." As applied to the specific DNA insert recited, this latter language appears to include within the scope of the claims all degenerate DNA sequences which encode the same polypeptide encoded by that DNA insert
As set forth in Wilhelmi, at the time of the present invention, growth hormone from the pituitaries of various animals including pigs, rats, and humans had been separated. Appellants set forth in the Background Art portion of the specification that growth hormones are known to, inter alia, promote skeletal growth, weight gain, and meat production in animals. Appellants acknowledge that purified swine growth hormone has been injected in pigs in order to lessen feed consumption and improve carcass quality but that the use of swine growth hormone for such purposes is limited since extracting swine growth hormone from pituitary glands of swine is not adequate to provide the needed commercial quantities of this hormone.
The modern technology of genetic engineering has allowed the cloning and expression in hosts of DNA for various growth hormones prior to the present invention. For example, Martial describes the cloning and expression in bacteria of cDNA to human growth hormone mRNA while Miller describes molecular cloning of cDNA to bovine growth hormone mRNA. The synthesis of growth hormones in bacteria based upon such cDNA expectedly provides greater quantities of these hormones than obtained from extracting pituitary glands.
The partial amino acid sequence of swine growth hormone and its homology to human and bovine growth hormone was known at the time of the present invention. See Figure 1 of Mills and Figure 1 of Wilhelmi. Miller cloned cDNA to bovine growth hormone mRNA by a procedure which used full length rat growth hormone cDNA as the probe in the hybridization step. Miller also sets forth the amino acid and nucleotide homologies among bovine, human and rat growth hormones in Table I. Martial similarly sets forth the amino acid and nucleic acid sequence homology of human and rat growth hormone.
*3 Thus, at the time of the present invention, one of ordinary skill in the art had ample reason to isolate a DNA sequence encoding swine growth hormone so that an appropriate host could be transformed therewith. In this manner, larger quantities of this valuable hormone could be obtained. This hypothetical person of ordinary skill had knowledge of the partial amino acid sequence of swine growth hormone and its homology to rat, bovine, and human growth hormones as well as the nucleotide homology of the DNA sequences encoding for rat, bovine, and human growth hormone was known. In addition, workers in this field had already isolated a DNA sequence encoding bovine growth hormone using a full length rat growth hormone cDNA as a probe.
OPINION
The rejection before us for review contains two alternative lines of reasoning in support of the examiner's conclusion of obviousness. The first relies upon Miller, Martial, Wilhelmi and Mills. The second relies upon these four references and Suggs. For the sake of clarity, we will consider the rejection as if it were two separate rejections.
Appellants have argued the merits of claims 3 through 6 as one group and claims 9 through 16 as a second group on the basis of claims 3 through 6 being directed to recombinant DNA molecules and claims 9 through 16 being directed to methods for producing polypeptides having the biological properties of swine growth hormone. Accordingly, we will discuss the issues in this appeal as they apply to claims 3 and 9 which are respectively the broadest recombinant DNA molecule and method claim pending. [FN2] In re Burckel, 592 F.2d 1175, 201 USPQ 67 (CCPA1979); 37 CFR § 1.192(c)(5).
CLAIM 2
MILLER, MARTIAL, WILHELMI AND MILLS
This aspect of the rejection involves the ability of Miller to clone cDNA to bovine growth hormone mRNA. This procedure included extracting total RNA from bovine pituitaries and preparing polyadenylated RNA therefrom which was subsequently reversed-transcribed into single-stranded cDNA. This material was subsequently inserted in plasmids and bacteria were transformed therewith. The presence of a growth hormone gene sequence in the transformed microorganisms was determined by hybridization of cloned, full length rat growth hormone cDNA. The use of the full length rat growth hormone cDNA as a probe resulted in the isolation of a DNA sequence encoding for bovine growth hormone.
In view of the success of Miller and the prior art knowledge of the homology between the amino acid and nucleotide sequences for rat, bovine, and human growth hormones, the examiner concluded that one of ordinary skill in the art would have found it obvious to isolate a DNA sequence encoding for swine growth hormone using the appropriately modified process of Miller. We agree.
Miller does disclose that full length cDNA encoding for rat growth hormone is sufficiently complementary to cDNA encoding for bovine growth hormone that the latter may be isolated by using the former. The prior art also recognized the high degree of homology for both the amino acid and nucleotide sequences of rat, bovine, and human growth hormones. The prior art also recognized that, to the extent the amino acid sequence for swine growth hormone was known at the time of the present invention, it also had a high degree of homology to the amino acid sequences of bovine and human growth hormones. These prior art facts provide a proper basis for concluding that one of ordinary skill in the art would have had a reasonable expectation of success in isolating a DNA sequence encoding for swine growth hormone from an appropriately prepared cDNA library by the art taught procedure using a probe based upon cDNA encoding for rat, bovine or human growth hormone. In re O'Farrell, 853 F.2d 894, 7 USPQ2d 1673 (Fed.Cir.1988).
*4 Appellants argue that Miller considered successful hybridization between rat growth hormone cDNA and bovine growth hormone cDNA feasible because the overall nucleotide sequence homology between the genes encoding the growth hormones of those species was known to be 83.9%, citing page 7521, column 2 of the reference. [FN3] However, contrary to the tenor of appellant's argument, the determination of the homology for the nucleotide sequences which encode for rat and bovine growth hormones appears to be based upon Miller cloning and sequencing for the first time cDNA encoding bovine growth hormone, i.e., while the amino acid homology for the respective proteins was known to Miller prior to that work, the nucleotide homology was not determined until they successfully used full length rat growth hormone cDNA to isolate the bovine growth hormone cDNA. Miller's decision to use the rat growth hormone cDNA as the probe in that work appears to have been based upon the known amino acid homology of the respective proteins.
Appellants argue that in order for one to successfully screen and select a desired sequence from a cDNA library as in Miller and as proposed in the rejection before us, "the degree of homology between the probe and target gene must be high enough to permit specific hybridization and selection of the desired gene from the other DNA sequences in the library" (Appeal Brief, page 12). Appellants argue that since the prior art did not know the DNA sequence which encodes for swine growth hormone, a person of ordinary skill in the art would not have had a reasonable expectation of success in screening an appropriate cDNA library with cDNA which encodes for other growth hormones as proposed in the rejection.
These arguments do not take into account that the amino acid and nucleotide homology among bovine, human, and rat growth hormones was known at the time of the present invention to be quite high. Nor do these arguments take into account the specific position of the examiner on pages 12-15 of the Examiner's Answer that the prior art establishes that the growth hormone gene has been highly conserved during the mammalian evolution.
Appellants rely upon Richards [FN4] for its disclosure that mouse glandular kallikrein shared only 57% nucleotide sequence similarity with porcine pancreatic kallikrein and that such a dissimilarity would prevent hybridization selection of a swine gene using a mouse gene. We have carefully considered appellants' arguments in this regard but agree with the examiner's response set forth at pages 16-17 of the Examiner's Answer that Richards is of little relevance to the issue at hand. The examiner specifically determined that:
The data provided by Richards et al. is not found persuasive with regard to the instant growth hormone genes. The genes and gene products discussed by Richards et al. belong to the broad and diverse family of serine proteases, with at least 4 other related members (genes encoding related serine protease) being expressed in mouse submaxillary gland (see col. 1, last paragraph to col. end of that paragraph 2, page 2760). Additionally, Richards et al. teach that their putative mouse kallikrein is only kallikrein-like. Is the mouse kallikrein a true homolog of porcine kallikrein or a distant relative? It is not clear from the Richards analysis. Clearly the situation in Richards et al., due to the broad nature and diversity of serine proteases, would cause one to have a lower expectation of isolating a homologous true kallikrein gene from porcine using the kallikrein-like murine gene. The facts are much different for the instant growth hormone genes. The instant growth hormone genes are not part of a family of related genes in the sense of serine proteases. Albeit with expected slight variability in the prior art sequences and the relatedness of growth hormone to other mammalian genes such as prolactin, it is the same gene in all mammalia, being expressed in high concentration primarily in pituitary. The serine protease genes of Richards et al. have been expressed in various tissue. It is not even clear that the instant murine and porcine kallikrein are the same gene; at best they are only members of a diverse family of many different genes. With growth hormone in mammalia, the evidence of the prior art shows that it is the same gene and only one, expressed primarily from the same nervous tissue, pituitary, having been highly conserved in mammalia for both nucleotide sequence in coding and non-coding regions and amino acid sequences over the course of evolution. The use of a teaching comparing kallikrein-like genes is not a valid comparison or art analogous example with the instant growth hormone genes.
*5 Appellants also rely upon Grantham [FN5] as evidence of uncertainty in isolating DNA encoding for swine growth hormone using other mammalian growth DNAs. Again, we agree with the examiner's rebuttal of appellants' position in the paragraph bridging pages 17-18 of the Examiner's Answer as follows:
Appellants argue further that Grantham et al. (cited by appellants in the instant brief) teaches away from expected homology of the known growth hormone genes to that of porcine and use as support the codon bias of hgh compared to rgh. It is true that rgh and hgh are not as homologous as that for bgh versus rgh, and it was even admitted above that there may be problems with using the human sequences to isolate pgh gene. However, the prior art shows that there are highly conserved regions in both the nucleotide and amino acid sequences encoding BGH, HGH, and RGH and in the non-coding regions of the genes also. One of ordinary [sic] would have known to use these conserved regions with a reasonable expectation of success and would have reasoned further that porcine would also have at least some of these conserved regions as argued above. Furthermore one of ordinary skill would have known to take into account porcine codon bias in the construction of oligonucleotide probes whether using the other mammalian amino acid sequences or that disclosed for porcine by Mills et al. or Wilhelmi et al.
Appellants also rely upon that portion of Amgen Inc. v. Chugai Pharmaceutical Co., 927 F.2d 1200, 18 USPQ2d 1016 (Fed.Cir.1991) concerning a prior art rejection based upon probing a cDNA library to isolate a gene of interest (18 USPQ2d at 1022-23) as precedent for reversing the present rejection. We have carefully considered appellants' reliance upon Amgen but agree with the examiner that the facts in that case are readily distinguished from the facts herein.
While a monkey cDNA for the protein of interest in Amgen was known, it was only known that the overall homology of genomic monkey DNA and human DNA was "roughly 90%." The court noted that neither the DNA sequence of the human gene nor its exact degree of homology with the monkey gene was known at that time. While the same can be said for the present facts, the gene of interest here is part of a family of mammalian genes, the sequences of at least three were known and shown to share highly conserved regions. Furthermore, unlike the facts in Amgen, the present prior art had successfully isolated similar genes of interest using probes based upon one of these known nucleotide sequences.
SUGGS
Suggs is relied upon by the examiner for disclosing an alternative manner of screening a cDNA library in order to isolate a desired DNA sequence. Specifically, Suggs discloses a general approach of using synthetic oligonucleotides as hybridization probes by chemically synthesizing a mixture of oligonucleotides that represents all possible codon combinations for a small portion of the amino acid sequence of a given protein. Suggs states that within this mixture there will be one sequence complementary to the DNA encoding for that part of the protein which will form a perfectly base pair duplex with the DNA from the coding region for the protein in contrast to the other oligonucleotides in the mixture which will form mismatched duplexes. A key aspect to this general approach of isolating a DNA sequence of interest is the use of stringent hybridization conditions so that only the perfectly matched duplex will form. In this manner the degenerate mixture of oligonucleotides can be used as a specific hybridization probe. Suggs specifically discloses in the first full paragraph of page 6613 that "Mixed sequence oligonucleotide probes should allow isolation of cloned DNA sequences for any protein for which the amino acid sequence is known." This statement of general utility is repeated at the end of the article.
*6 This portion of the rejection is also premised upon the prior art knowledge of the partial amino acid sequence of swine growth hormone. The examiner has reasoned that one of ordinary skill in the art would have found it obvious to prepare an appropriate cDNA library from swine pituitary glands in the manner which Miller did with bovine pituitary glands and probe that library in order to isolate DNA encoding for swine growth hormone using a set of probes based upon the known partial amino acid sequence of swine growth hormone using the technique of Suggs. We agree.
Appellants argue that Suggs was able to take advantage of the particular amino acid sequence of the protein used in that reference to select favorable codon combinations which could not be selected from the swine growth hormone amino acid sequences known in the prior art at the time of the invention. Appellants specifically argue that the partial swine growth hormone sequences known at the time of the present invention were 4-times as degenerate as Suggs' 8-fold degenerate probe and 2-times as degenerate as Suggs' 16-fold degenerate probe. Appellants go on to argue that screening a swine cDNA library with a probe deduced from a highly conserved region would just as likely select DNA encoding for other family members of proteins having similar biological activity such as prolactin rather than DNA coding for swine growth hormone.
These arguments do not take into account that portion of the procedure of Suggs which involves the use of stringent hybridization techniques so that only a perfectly base pair duplex with DNA from the coding region for the protein of interest will be formed which eliminates mismatched pairs. Further, assuming per the argument that the probe pool could form a perfect match with a related gene as well as with the gene of interest, one of ordinary skill in the art would be sufficiently skilled to determine which perfect match included the gene of interest.
Appellants also argue that it may be inferred from Suggs that that technique could not be used for swine growth hormone. Specifically, appellants state that the least degenerate 15-mer target in the swine growth hormone amino acid fragment disclosed by Mills is 32-fold degenerate. Appellants note that there was also a peptide target for a 32-fold degenerate 15-mer in the protein used in Suggs, yet Suggs chose an 11-mer of only 8-fold degeneracy, which did not work. However, that portion of Suggs relied upon by appellants, the paragraph bridging the columns of page 6616, states that the failure of the 8-fold, 11- base-long oligonucleotides may have reflected differences in the hybridization procedures used. Suggs specifically states that subsequent experiments using oligonucleotide probes longer than 11 bases were used to isolate cloned sequences for other proteins.
In any event, the successful results reported in Suggs as well as the conclusion reached by the authors of that article that the successful results establish that this technique may be used to isolate cloned DNAs for any protein for which the amino acid sequence is known outweigh the specific technical difficulties reported for that one clone.
*7 Appellants' arguments concerning the possible incorrect amino acid sequences being set forth in Mills and Wilhelmi for swine growth hormone are unsupported by any evidence of record. Furthermore, arguments concerning the purported difficulty in forming oligonucleotide probe mixtures needed to perform the probing procedure of Suggs are similarly unsupported by evidence of record and ignore the specific success achieved in Suggs as well as the general statements of utility contained in this reference. [FN6]
Nor are we impressed by appellants' argument that one of the co-authors of Suggs was an employee of the present assignee and yet the technique of Suggs was not employed by this co-author or assignee to swine growth hormone. The statutory standard of obviousness involves the hypothetical person of ordinary skill in the art, not the actual inventors or authors of references used as evidence of obviousness.
Appellants also cite and rely upon a number of non-prior art foreign patent applications directed to swine growth hormone. However, we do not find that these non-prior art documents are particularly relevant to the present obviousness determination. The issue to be resolved is whether the prior art would have rendered the claimed subject matter obvious. The fact that other parties isolated DNA encoding swine growth hormone or made use of such an isolated sequence after the filing date of this application does not militate against a conclusion of obviousness. [FN7]
Appellants also rely upon the recent decision in In re Bell, --- F2d ----, 26 USPQ2d 1529 (Fed.Cir.1993) in arguing the nonobviousness of the subject matter on appeal. We have carefully considered the facts and decision in Bell, but do not find that that decision necessitates reversal of either facet of the rejection before us.
The facts in Bell are similar to the present in that the claims were directed to isolated DNA sequences encoding for a protein and the prior art of record disclosed the amino acid sequence of the protein but not a specific nucleotide sequence which encoded for that protein. A reference to Weissmann was relied upon in the rejection under review in Bell for its disclosure of a probing procedure based on amino acids specified by unique codons. In reversing the prior art rejection, the court noted that Bell had argued without contradiction that the amino acid sequences under consideration therein could be coded for by more than 1036 nucleotide sequences, only a few of which were the sequences there claimed.
In considering appellants' arguments based on Bell, we note that equivalent evidence is not of record in this application. Furthermore, the protein of interest in this application is part of a family of growth hormones. It is not apparent from the reported decision that the protein of interest in Bell was part of such a family or that the prior art relied upon in the rejection included successful isolation of DNA sequences which encoded that protein for different species as in this appeal. Patentability determinations under 35 USC § 103 are fact driven. We do not find the reported facts of Bell to be so similar to those in this appeal that the decision in Bell should be considered controlling. Here, we find the evidence of record supports the conclusion that one of ordinary skill in the art would have had a reasonable expectation of success in isolating a DNA sequence encoding swine growth hormone using the art taught techniques.
*8 A further point to be considered in considering the relevance of the decision in Bell to the present facts is the breadth of the present claims. While the present claims do require in part specific nucleotide sequences, they also appear to be inclusive of the degenerate sequences which encode for the same protein, i.e., any and all sequences which encode for the protein. If the reasonable expectation of success found to be lacking in Bell can be analogized to the likelihood of hitting the center of the bulls-eye on a dart board, the present reasonable expectation of success would be more akin to merely hitting any spot on the dart board.
CLAIM 9
The arguments made by appellants in regard to the method claims are essentially those made for the recombinant DNA sequence claims. Martial discloses the high level expression of the natural human growth hormone gene in bacteria. Having isolated a DNA sequence encoding for swine growth hormone using the prior art procedures discussed above, the person of ordinary skill in this art would be sufficiently skilled to transform an appropriate host and express this valuable protein.
The decision of the examiner is affirmed.
No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. § 1.136(a). See the final rule notice, 54 F.R. 29548 (July 13, 1989), 1105 O.G. 5 (August 1, 1989).
AFFIRMED
BOARD OF PATENT APPEALS AND INTERFERENCES
Melvin Goldstein
Examiner-in-Chief
James A. Seidleck
Examiner-in-Chief
Examiner-in-Chief
FN1. The examiner has cited and relied upon four new references in the Examiner's Answer but did not make a new ground of rejection. As set forth in In re Hoch, 57 CCPA 1292, 428 F.2d 1341, 166 USPQ 406 (1970), "[W]hen a reference is relied on to support a rejection, whether or not in a 'minor capacity,' there would appear to be no excuse for not positively including the reference in the statement of rejection." The failure of the examiner to do so here appears to be for the purpose of avoiding a new ground of rejection. Since a new ground of rejection was not made, appellants were not entitled as a matter of right to respond to this new evidence of obviousness by way of amendment and/or evidence. Rather, appellants were limited to presenting argument by way of a Reply Brief. The procedural disadvantage in which appellants were placed by the examiner's action is apparent. Accordingly, we have not considered the four references in determining the correctness of the rejection before us in this appeal. If in further prosecution of this subject matter, the examiner continues to find these references to be relevant evidence of obviousness (see n. 6, infra), a proper rejection should be made.
FN2. Appellants have grouped claims 12 through 14 which are directed to recombinant DNA molecules with the method claims. Regardless of whether this is considered the most appropriate grouping for these claims, appellants have not provided separate arguments for these claims.
FN3. We do not find that value disclosed in the cited portion of the reference. Rather, that value is set forth in Table I of Miller.
FN4. R.I. Richards et al., "Mouse Glandular Kallikrein Genes", J.Biol.Chem. 257(6), pp. 2758-61 (1982) (Exhibit C to applicants' November 25, 1991 Response).
FN5. R. Grantham et al., "Coding Frequencies In Individual Genes Confirm Consistent Choices Of Degenerate Bases According To Genome Type", Nucleic Acids Research, 8, pp. 1893-1912 (1980) (Exhibit D to applicants' November 25, 1991 Response).
FN6. One of the references the examiner belatedly relied upon in the Examiner's Answer, Maniatis et al. (Maniatis), "Low-Abundance mRNAs", Molecular Cloning, A Laboratory Manual, pages 225-227 (References; pages 507-519 (1982), is relevant evidence concerning the acceptance of the probing procedure of Suggs by the art. This standard reference text in the field of molecular cloning states that the method of Suggs is a useful approach in cloning cDNA. We decline to exercise our discretion and enter a new ground of rejection under 37 CFR § 1.196(b) relying upon Maniatis as additional evidence of obviousness. However, if prosecution of this subject matter is continued, appellants and the examiner should consider this relevant reference.
FN7. If the use of other techniques made public after the effective filing date of the present application is relevant in determining the patentability of the claimed subject matter, e.g., as evidence of the level of skill in the art, Ashland Oil, Inc. v. Delta Resins & Refractories, Inc., 776 F.2d 281, 227 USPQ 657 (Fed.Cir.1985), In re Farrenkopf, 713 F.2d 714, 219 USPQ 1 (CCPA 1983); such a determination should take into account the disclosure of Seeburg et al., DNA, 2 (1983) 37-45 (copy already of record). Seeburg reports the successful obtention of DNA encoding swine growth hormone using a method similar to that of Miller using cloned DNA from rat growth hormone mRNA as the probe, i.e., the method proposed in the first part of the present rejection.
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