Chemistry: molecular biology and microbiology – Vector – per se
Reexamination Certificate
1998-10-07
2001-06-19
Park, Hankyel T. (Department: 1648)
Chemistry: molecular biology and microbiology
Vector, per se
C435S005000, C435S006120, C530S324000, C536S023100, C424S160100, C424S207100
Reexamination Certificate
active
06248582
ABSTRACT:
FIELD OF INVENTION
This invention relates to the field of viral vaccines, particularly to use and production of genetically deleted feline leukemia virus proviral DNA that produce nonreplicating virus particles in vivo. The DNA can also be used to produce immunogenic polypeptides derived from the FeLV genome. These vaccines are especially useful against FeLV and the disease associated with FeLV.
BACKGROUND OF THE INVENTION
Feline leukemia virus (FeLV) is an exogenous type C retrovirus of the Retrovirdae virus family. It is associated with multiple immunosuppressive diseases specifically with the lymphoreticular disease, including lymphosarcoma, leukemia, aplastic anemia, myelodysplasis and feline acquired immunodeficiency syndrome Hardy et al.,
Cancer Res.
36:582, 1976; Hardy Feline Leukemia Virus, Hardy, Essex, McCelland, eds. (Elsevier/North Holland, 1980), pp.3-31; Hoover, Rojko, Olsen,
Feline Leukemia,
Olsen, ed. (CRC Press, Boca Raton, Fla., 1980), pp.32-51; Hardy and Essex,
Prog. Allergy
37:353, 1986). FeLV isolates are divided into three subgroups A, B, and C based on their interference and neutralization patterns (Sarma et al.
Virology
44:352-358 (1971); Donahue, P. R. et. al.
J. Virol.
66:722-731 (1988); Jarret, O. et. al.
Int. J. Cancer
21:334-387 (1978). FeLV-A is found in every isolate in nature either alone or in combination with B and C subgroups and is considered to be the subgroup most responsible for viremia and the latent carrier state. FeLV-B is found in about 40% of all infections whereas FeLV-C is found in only 1% of infections and occurs in combinations with B and A subgroups. Because FeLV-A demonstrates a more restricted cell tropism in vitro and tends to be less pathogenic, the presence of subgroup A in all infections makes it the obvious target for prevention of FeLV infection (Loar, A. S. Vet. Cl. N. Amer. 23:193-211).
Pharmaceutical compounds that will eliminate or control virus replication once the virus is introduced in cats have not been well tested; however, several preventative vaccines have been developed. FeLV vaccines are sold under at least 8 different trade names including at least 3 combination products from 4 different manufacturers. The product tradenames include: Leukocell and Leukocell 2 (Pfizer), Leukogen (Virbac), Gentivac (Schering(Coopers), RM Leucat (Rhone-Merieux/MERIAL), Fevaxyn (Schering/Solvay), FeloVax (Fort Dodge), and VacSYN/FeLV (Symbiotics). These vaccine preparations include infected cell extracts, whole virus preparations, and recombinant envelop protein subunit vaccines. In addition to these commercial vaccines, there are several disclosures that describe other possible methods for immunization against FeLV including treatments with recombinant derived FeLV peptides alone or in combination with attenuated virus or proviral DNA preparations (U.S. Pat. Nos. 4,701,416, 4,876,089, 5,152,982, 4,789,702, EPO 0247904, PCT U.S.85/02319), virus vectors expressing FeLV gene products (U.S. Pat. Nos. 4,957,865, 5,324,664, PCT U.S. Ser. No. 88/02816, GB90/00116, U.S. Ser. No. 92/08427), peptide vaccines containing smaller components of full length gene products (U.S. Pat. Nos. 4,663,436, 4,794,168), self-assembled replication-deficient virus particle production, and vector produced non-replicative virus particle production (PCT U.S. Ser. No. 93/09070).
Despite the variety of FeLV approaches to vaccine development and utilization there are still important and pertinent features that the present preventative or therapeutic treatments do not provide. None of the vaccines utilize an antigen or vaccination method that allows for cross protection against all field isolates and subgroups nor do they include components that provide protection against other immunosuppressive or immunodeficient viruses such as FIV or FIPV. Vaccines, which use non-purified virus or infected cell material have inconsistencies in the amount of virus-associated material that exist in each vaccine preparation. As a consequence there is variability with these vaccines in both delayed and immediate site reactions. In addition, retroviruses are notoriously low producers in cell culture and are relatively unstable in unprocessed or non-cryopreserved forms, which contributes to limited storage periods of FeLV components in manufacturing. As a consequence the FeLV is often the limiting antigen when attempting to develop combination vaccines with other infectious disease agents of felines. In general, there is also an inability to determine and to discriminate subgroups A, B and C within the vaccine and manufacturing material. Because all existing FeLV vaccines on the market are inactivated (killed) preparations, two and sometimes three doses are recommended for active immunization of cats. Because of these limitations within the present commercial products and continued demands by the clinician for managing and controlling immunosuppressive disease there is a need in the art for improved methods for immunization against FeLV and associated disease.
The present invention is provided to address all of the above needs. In particular it provides a FeLV vaccine that cannot only deliver an efficacious dose of FeLV in a convenient administration, but can also be manufactured in a more consistent manner than previous art. In addition, the invention described here is derived from a new isolate of FeLV (BTI-FeLV-A) taken from a cat in Fair Oaks, Calif. This virus is subgroup A has not been described before and represents a virus isolate that has evaded or is not controlled by current vaccination programs.
SUMMARY OF THE INVENTION
The present invention provides compositions and methods for inducing immune responses against FeLV. In some embodiments, the compositions comprise a nucleic acid molecule comprising a truncated FeLV genome. The nucleic acids comprise an env gene from FeLV from BTI-FeLV-A. The nucleic acid can be incorporated into an expression vector according to well known methods. This expression vector can be used to vaccinate cats against FeLV and FeLV associated diseases; this vector can also be amplified in bacterial hosts so as to allow for consistent and reliable production of the gene product under fermentation parameters and DNA purification methods.
In one aspect of the invention a bacterial plasmid DNA has been genetically recombined to a provirus DNA of FeLV that has been truncated in the polymerase (pol) gene to remove the capability of producing new genetic templates of FeLV-genome specificity. In an embodiment, the proviral DNA has been isolated from a new isolate of feline leukemia virus that has homology to subtype A based on partial sequence of the envelope gene. In another embodiment, the FeLV proviral DNA has been debilitated in that the long terminal repeat (LTR) on the 3′ end and 5′ ends of the genome have been removed from the proviral DNA. In another embodiment the integrase functions of the polymerase (Po) gene have been deleted. In another embodiment the proviral DNA has a cytomegalovirus (CMV) early promoter region on the 5′ end of the genome to drive expression of the FeLV viral genes and a bovine growth hormone gene (BGH) poly A addition signal recombined at the 3′ end of the genome to terminate viral mRNA synthesis. In another embodiment the modified FeLV proviral DNA encodes and can express the entire gag and envelope gene (env) products of FeLV. Another aspect of this invention is the production of non-replicating virus particles in vivo from the intramuscular injection of the purified plasmid encoding the truncated form of FeLV proviral DNA. In an embodiment, the non-replicating viral particles have the following characteristics:
they contain no detectable FeLV genomic RNA but retain specificity of the group specific antigen (gag) and envelope antigens (env) of the virus particle.
the virus particles produced from the truncated form of FeLV proviral DNA are capable of attaching and penetrating the target tissue of the host animal and inducing both cellular and humoral immunity.
the virus particles of
Khan Imran
York Charles J.
Park Hankyel T.
Townsend and Townsend / and Crew LLP
LandOfFree
Gene deleted recombinant FeLV proviral DNA for production of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gene deleted recombinant FeLV proviral DNA for production of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gene deleted recombinant FeLV proviral DNA for production of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2495813