Passive antibody protection of cats against feline immunodeficiency virus infection

Self Cite

109

and Aomori-2, were isolated from FIV-seropositive domestic cats in Japan, and their proviral DNAs were amplified by PCR. The nucleotide sequences of their env and gag genes were determined and compared with those of previously described isolates: U.S. and European isolates and one Japanese isolate, TM2. Phylogenetic analyses of complete env gene sequences demonstrate that worldwide isolates are classified into three subtypes: Japanese TM2, Japanese Shizuoka, and non-Japanese subtypes (U.S. and European isolates), with 20% amino acid distances from each other. This pattern indicates that an evolutionary radiation of these three subtypes of FIV occurred at approximately the same time. The sequence data of gag genes also confirmed these results. Furthermore, the Sendai-1 isolate was identified as an imported FIV isolate.

mentioning

confidence: 99%

Nucleotide sequence of feline immunodeficiency virus: classification of Japanese isolates into two subtypes which are distinct from non-Japanese subtypes

Kakinuma

Motokawa

Hohdatsu

et al. 1995

Self Cite

109

“…However, Yamamoto et al reported the induction of protective immunity in cats against homologous and to a lesser extent also to heterologous FIV challenge, by vaccination with inactivated whole virus or FIV-infected cells (49,50). This protective effect could be transferred to naive cats with plasma from vaccinated animals, indicating that antibodies may be at the basis of this protective immunity (13). It was shown that serum antibodies against FIV envelope glycoproteins, with different VN domains, correlated more with protective immunity than did antibodies to other viral proteins.…”

mentioning

confidence: 99%

Enhancement of feline immunodeficiency virus infection after immunization with envelope glycoprotein subunit vaccines

Siebelink

Tijhaar

Huisman

et al. 1995

108

Cats were immunized three times with different recombinant feline immunodeficiency virus (FIV) candidate vaccines. Recombinant vaccinia virus (rVV)-expressed envelope glycoprotein with (vGR657) or without (vGR657x15) the cleavage site and an FIV envelope bacterial fusion protein (␤-Galactosidase-Env) were incorporated into immune-stimulating complexes or adjuvanted with Quil A. Although all immunized cats developed antibodies against the envelope protein, only the cats vaccinated with the rVV-expressed envelope glycoproteins developed antibodies which neutralized FIV infection of Crandell feline kidney cells. These antibodies failed to neutralize infection of thymocytes with a molecularly cloned homologous FIV. After the third immunization the cats were challenged with homologous FIV. Two weeks after challenge the cellassociated viral load proved to be significantly higher in the cats immunized with vGR657 and vGR657x15 than in the other cats. The cats immunized with vGR657 and vGR657x15 also developed antibodies against the Gag proteins more rapidly than the cats immunized with ␤-Galactosidase-Env or the control cats. This suggested that immunization with rVV-expressed glycoprotein of FIV results in enhanced infectivity of FIV. It was shown that the observed enhancement could be transferred to naive cats with plasma collected at the day of challenge.

“…Another possibility is that cell-mediated responses rather than humoral factors are critical for defending against FIV. Attempts to transfer protection against lentiviruses by means of passively administered antibodies obtained from vaccinated hosts have provided contradictory results (2,9,12,33,40,44) and in one study have even accelerated FIV challenge infection (69). Our prior studies have failed to find a correlation between FIV-specific T-cell-proliferative responses of PBMC from vaccinated cats and protection (47,48); however, the role of FIV-specific cytotoxic T lymphocytes induced by vaccines is under scrutiny (22,23,35,74).…”

Section: Discussionmentioning

confidence: 99%

AIDS Vaccination Studies Using an Ex Vivo Feline Immunodeficiency Virus Model: Detailed Analysis of the Humoral Immune Response to a Protective Vaccine

Mazzetti

Giannecchini

Mauro

et al. 1999

The feline immunodeficiency virus (FIV) cat model is extensively used to investigate possible vaccination approaches against AIDS in humans. Although consistent levels of protection have been achieved with FIV, as with other model systems, by immunizing with whole inactivated virus or fixed infected cells, the mechanisms responsible for protection are elusive. In previous studies we showed that cats immunized with a vaccine consisting of fixed infected cells were protected or unprotected against cell-free or cell-associated FIV challenge depending on the time interval between completion of vaccination and challenge. In an attempt to define possible humoral immune correlates of protection, selected sera harvested at the times of challenge from such cats were examined for anti-FIV-antibody titers and properties by using binding and functional immunological assays. Binding assays included quantitative Western blotting, enzyme-linked tests for antibodies to FIV glycoproteins and immunodominant linear epitopes, and tests for measuring conformation dependence and avidity of anti-viral-envelope antibodies. Functional assays included virus neutralization performed with two different cell substrates, complement- and antibody-dependent virolysis, blocking of reverse transcriptase, and an assay that measured the ability of sera to prevent FIV growth in cocultures of infected and uninfected cells. Despite the wide spectrum of parameters investigated, no correlation between vaccine-induced protection and the humoral parameters measured was noted.