Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Carbohydrate doai
Reexamination Certificate
2000-06-14
2003-12-23
Guzo, David (Department: 1636)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Carbohydrate doai
C424S093100, C424S093200, C424S093600, C424S278100, C424S281100, C424S188100, C424S204100, C424S208100, C536S023100, C536S023720
Reexamination Certificate
active
06667295
ABSTRACT:
1. FIELD OF THE INVENTION
The present invention is in the field of animal health, and is directed to vaccine compositions and diagnostics for disease. More particularly, the present invention relates to polynucleotide molecules that can be used as vaccine components against feline immunodeficiency virus.
2. BACKGROUND OF THE INVENTION
Feline immunodeficiency virus (FIV) infection in cats results in a disease syndrome similar to that caused in humans by human immunodeficiency virus-1 (HIV-1) infection. After infection of cats by FIV, disease progression begins with a transient acute phase illness (8 to 10 weeks), followed by a prolonged asymptomatic phase varying from weeks to years, and a terminal symptomatic phase (Ishida and Tomoda, 1990, Jpn. J. Vet Sci. 52:645-648; English et al., 1994, J. Infect. Dis. 170: 543-552). Similar to HIV-1 disease progression (Graziosi et al., 1993, Proc. Natl. Acad. Sci. 90:6405-6409; Baumberger et al., 1993, AIDS 7:S59-S64; Wei et al., 1995, Nature 373:117-122), FIV RNA load in plasma has been demonstrated to correlate with disease stage, and can predict disease progression in accelerated FIV infection (Diehl et al., 1995, J. Virol. 69:2328-2332; Diehl et al., 1996, J. Virol. 70:2503-2507).
Based on the genetic diversity of the ENV protein of FIV, especially the V3 region, five FIV subtypes have been proposed: subtypes A and B, mainly in North America, Europe and Japan; subtype C in British Columbia and Taiwan; subtype D in Japan; and subtype E in Argentina (Sodora et al., 1994, J. Virol. 68:2230-2238; Kakinuma et al., 1995, J. Virol. 69:3639-3646; and Pecoraro et al., 1996, J. Gen. Virol. 77:2031-2035).
Similar to other lentiviruses, such as HIV-1, the FIV genome contains three large open reading frames, i.e., GAG (group antigens), ENV (envelope), and POL (polymerase), and three small open reading frames encoding regulatory (i.e., non-structural) proteins, i.e., Rev (regulator of expression of virion protein), Vif (virion infectivity factor) and ORF2 (open reading frame 2). The provirus contains two long terminal repeats (LTR), one at each end of the genome (Talbott et al., 1989, Proc. Natl. Acad. Sci. USA 86:5743-5747; Olmsted et al., 1989, Proc. Natl. Acad. Sci. USA 86:8088-8092). GAG is a precursor polyprotein that is processed into three mature virion structural proteins, i.e., the matrix (MA), capsid (CA) and nucleocapsid (NC) proteins. ENV is a precursor protein that is processed into two envelope structural proteins, i.e., the surface (SU) and transmembrane (TM) proteins. POL encodes four enzymatic (i.e., non-structural) proteins, i.e., protease (PR), reverse transcriptase (RT), deoxyuridine triphosphatase (DU) and integrase (IN).
The mechanism by which protective immunity against FIV infection can be achieved remains poorly understood. It has been reported by some groups that virus neutralizing (VN) antibodies appear to play a major role in the observed protection (Yamamoto et al., 1991, AIDS Res. Hum. Retrovir. 7:911-922; Hosie et al., 1995, J. Virol. 69:1253-1255). Consistent with those observations was the finding that cats who passively received antibodies from vaccinated or infected cats were protected from homologous challenge (Hohdatsu et al., 1993, J. Virol. 67:2344-2348; Pu et al., 1995, AIDS 9:235-242).
By contrast, convincing data also indicates that the levels of antibodies, or even VN antibodies, do not correlate with protection. It has been reported that cats were protected against homologous challenge in the absence of detectable VN antibodies (Verschoor et al., 1995, Vet. Immunol. Immunopathol. 46:139-149; Matteucci et al., 1996, J. Virol. 70:617-622). In addition, other vaccinated cats failed to be protected in the presence of significant VN antibodies (Huisman et al., 1998, Vaccine 16:181-187; Flynn et al., 1997 J. Virol. 71:7586-7592; Tijhaar et al., 1997, Vaccine 15:587-596; Osterhaus et al., 1996, AIDS Res. Hum. Retrovir. 12:437-441; Verschoor et al., 1996, Vaccine 14:285-289; Rigby et al., 1996, Vaccine 14:1095-1102; Lutz et al., 1995, Vet. Immunol. Immunopathol. 46:103-113; Flynn et al., 1995, Immunol. 85:171-175; Gonin et al., 1995, Vet. Microbiol. 45:393-401). This discrepancy appears to result, at least partially, from the different cell systems and virus isolates used in the VN assays. It has recently become evident that fresh isolates of FIV obtained from naturally infected cats are much less sensitive to VN antibodies than laboratory viruses adapted to growth in tissue culture (Baldinotti et al., 1994, J. Virol. 68: 4572-4579). It has also been found that the same antibodies which neutralized FIV infection in Crandell Feline Kidney (CRFK) cells failed to neutralize FIV infection in primary feline thymocytes (Huisman et al., 1998, above). These data indicate that the VN antibodies detected in vitro may not play any role in protective immunity in vivo.
In a few limited reports, cell-mediated immunity was investigated following vaccination. In one report, it was found that cellular immunity, especially ENV-specific CTL responses, played a major role in protecting cats vaccinated with whole inactivated virus (Flynn et al., 1996, J. Immunol. 157:3658-3665; Flynn et al., 1995, AIDS Res. Hum. Retrovir. 11:1107-1113). It was also reported that long-term protection was more closely correlated with the induction of ENV-specific cytotoxic T-cell activity (Hosie and Flynn, 1996, J. Virol. 70:7561-7568).
It appears that both humoral and cellular immunity are involved in achieving protective immunity in the acute phase after challenge, but for long-term protection, cell-mediated immunity appears to be more important. However, the question still remains which viral protein(s) or subunit(s) or combinations are capable of inducing protective immune responses. In one report, although both cell-mediated and humoral immune responses were induced in cats vaccinated with a multi-epitopic peptide within the ENV protein, vaccination did not confer protection against homologous challenge (Flynn et al., 1997, above).
As in HIV-1, an observation that complicates the development of an effective FIV vaccine is the enhancement of infection that has been observed in cats immunized with certain vaccines. Such enhancement of infection has been observed in a number of FIV vaccine trials in which either recombinant subunit vaccines, synthetic vaccines, whole inactivated virus vaccines or fixed, infected cell vaccines were used to vaccinate cats (Osterhaus et al., 1996, above; Siebelink et al., 1995, J. Virol. 69:3704-3711; Lombardi et al., 1994, J. Virol. 68:8374-8379; Hosie et al., 1992, Vet. Immunol. Immunopathol. 35:191-197; Huisman et al., 1998, above). For example, in an ENV subunit vaccine trial, enhancement of infection occurred despite anti-ENV and VN antibody production, and this enhancement could be transferred to naive cats via plasma pools from the vaccinated animals, indicating that the enhancement was probably mediated by specific antibodies (Siebelink et al., 1995, above).
It appears that antibodies against ENV tend to enhance infection more readily than antibodies against GAG protein. However, the mechanism by which antibodies enhance FIV infection remains poorly understood. In HIV-1, antibody-dependent enhancement requires that the target cells express either the immunoglobulin Fc receptor (FcR), or complement receptors (CRs). The enhancement is a biphasic response based on serum dilution; that is, at higher antibody concentrations, viral neutralization is observed, whereas enhancement is seen at lower antibody concentrations (Mascola et al., 1993, AIDS Res. Hum. Retrovir. 9:1175-1184). The enhanced infectivity may interfere with the induction of protective immunity in FIV , which may partially explain the reason why a large number of FIV vaccination experiments in which ENV protein or its subunits were used as vaccines were unsuccessful. Therefore, the rational development of vaccines against lentiviruses, including FIV and HIV-1, requires the careful assessment and selection of vaccine immunogens.
Since the discovery of
Ginsburg Paul H.
Guzo David
Kohn & Associates PLLC
Ling Lorraine B.
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