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Feline immunodeficiency virus-infected cat sera associated with the development of broad neutralization resistance in vivo drive similar reversions in vitro
No full textWe previously reported that, upon reinoculation into cats, a neutralization-sensitive, tissue culture-adapted strain of feline immunodeficiency virus constantly reverted to the broad neutralization resistance typical of primary virus isolates and identified residue 481 in the V4 region of the surface glycoprotein as a key determinant of the reversion. Here, we found that well-characterized immune sera, obtained from cats in which such reversion had occurred, selected in tissue culture in favor of virus variants that also had a neutralization-resistant phenotype and had amino acid 481 changed, thus indicating that the host's humoral immune response is capable of driving the reversion in the absence of other intervening factors. In contrast, a second group of immune sera, elicited by a virus variant that had already reverted to neutralization resistance in independent cats, induced the emergence of escape mutants lacking broad neutralization resistance and neutralized fewer virus variants. It is proposed that the viral variants used to produce the two sets of sera may have generated different antibody repertoires
Densitometric analysis of Western blot assays for feline immunodeficiency virus antibodies
No full textWestern blot (WB) strips for antibodies directed to feline immunodeficiency virus (FIV) were analysed using reflectance densitometry by a semiautomatic densitometer. This method was used to quantify the antibody responses to different FIV proteins in both vaccinated and naturally or experimentally-infected cats. In order to increase reproducibility, reagents and protocols were accurately standardised and internal controls were added. In a first format, an internal control band consisting of feline IgG was added to each blot to minimise the effect of band intensity variation. In a second format, antibody concentrations were calculated from the ratio of the dens ities produced by test sera and by positive and negative standard sera. The sera under scrutiny were also examined by standard enzyme-linked immunosorbent assay (ELISA) and the results obtained compared with those of the corresponding WB. A statistically significant positive correlation was found between the results obtained with the two methods, and this was especially evident when ELISA titres were compared to corrected WB values (P = 0.001). Densitometric analysis of WB assays allowed to quantify the antibodies against FIV proteins and might be useful to investigate possible humoral immune correlates of protection in FIV vaccination studies and antibody production in the early phase of infection. The quantitation of antibodies to Gag and Env FIV antigens might be used to obtain further informations on the course of FIV disease, as previously demonstrated in human immunodeficiency virus-1 (HIV-1) infections. (C) 2001 Elsevier Science B.V. All rights reserved
Antiviral activity and conformational features of an octapeptide derived from the membrane-proximal ectodomain of the feline immunodeficiency virus transmembrane glycoprotein
No full textDifferentiation and maturation of feline dendritic cells derived from peripheral blood monocytes for in vivo use
No full textImmunolocalizzazione del virus dell'immunodeficienza felina (FIV) in tessuti di gatti infetti
No full textRenal involvement in Feline Immunodeficiency Virus infection: p24 antigen detection, virus isolation and PCR analysis
No full textRenal alterations characterized morphologically by glomerular and tubulo-interstitial lesions and clinically by a heavy proteinuria and sometimes by renal failure are frequent in feline immunodeficiency virus (FIV) infected cats. To investigate the possible role of local FIV replication in the genesis of this renal damage, renal tissues of 15 consecutive naturally infected and five non-infected cats were examined for traces of the virus by immunohistochemistry, using a monoclonal anti-p24 antibody in a streptavidin-biotin peroxidase labeled system, cultivation and polymerase chain reaction (PCR). Tubular epithelial cells as well as scattered interstitial inflammatory and glomerular cells were positive for p24 antigen in 13 cats. Viral isolation was successful in seven cats, and FIV gag DNA and RNA sequences were detected in 14 and five cats, respectively, Control cats were constantly negative. Although not conclusive, these results suggest that a direct role of FIV in the induction of the renal damage observed in infected animals is possible
Evolution of two amino acid positions governing broad neutralization resistance in a strain of feline immunodeficiency virus over 7 years of persistence in cats
No full textFresh isolates of lentiviruses are characterized by an outstanding resistance to antibody-mediated neutralization. By investigating the changes that occurred in a neutralization-sensitive tissue culture-adapted strain of feline immunodeficiency virus after it was reinoculated into cats, a previous study had identified two amino acid positions of the surface glycoprotein (residues 481 and 557) which govern broad neutralization resistance (BNR) in this virus. By extending the follow-up of six independently evolving in vivo variants of such virus for up to 92 months, we now show that the changes at the two BNR-governing positions not only were remarkably stereotyped but also became fixed in an ordered sequential fashion with the duration of in vivo infection. In one variant, the two positions were also seen to slowly alternate at determining BNR. Evidence that evolution at the BNR-governing positions was accompanied, and possibly driven, by changes in the antigenic makeup of the viral surface brought about by the mutations at such positions is also presented
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