Monoclonal antibodies to immunodominant and neutralizing domains of the envelope surface protein of feline immunodeficiency virus

Abstract

Hybridomas secreting monoclonal antibodies (MAbs) specific for the surface protein (SU) of feline immunodeficiency virus were generated. Four MAbs were obtained which could be assigned to two groups based on their neutralization and competition behaviour. Using SU protein fragments expressed in Escherichia coli the antigenic site recognized by one of the MAbs (2H11) could be mapped to the c terminus. The neutralizing MAb 1El did not bind to any of the SU protein fragments and was directed to a conformational epitope. Binding of the MAb 1El to native SU protein could be blocked with a rabbit serum raised against the SU3 fragment (amino acids 361 to 445). These data indicate that at least part of the epitope is located on this SU3 domain. In competition experiments most sera of naturally infected cats were able to inhibit binding of the MAbs. This shows the conserved and immunodominant nature of the epitopes involved.

Autologous and Heterologous Neutralization Analyses of Primary Feline Immunodeficiency Virus Isolates

“…As for HIV-1 (35,55,57), the reasons for this diversity are not clear. In an SSCP analysis of the V3 and V4 regions, i.e., two env domains that have been implicated in FIV neutralization (5,10,21,25,38,47,54), we found no relationships between FIV quasispecies complexity and sensitivity to cross-neutralization, except that the variants detected in V3 were slightly more numerous in the crossneutralization-sensitive than in the nonsensitive isolates. Thus, NA susceptibility did not appear to be a function of a low degree of genetic polymorphism in the env regions examined, at least in primary isolates.…”

Feline immunodeficiency virus: an interesting model for AIDS studies and an important cat pathogen.

“…4) inhibited the FIV-neutralizing activity of pooled immune cat sera, and cat sera raised against this peptide effectively neutralized FIV infectivity for CrFK cells (120). This finding has been confirmed by characterization of a neutralizing serum produced by immunizing rabbits with a recombinant peptide (42) and a neutralizing monoclonal antibody which appeared, however, to bind a conformational epitope (52). Thus, it would appear that the V3 region could be of great interest as a component of a candidate vaccine against FIV.…”

FIV vaccine development and its importance to veterinary and human medicine: a review

“…The incorporated gene(s) must include genes for protective FIVepitopes and must be expressed at a suf®cient level for the vaccinated host to mount a speci®c immune response. Predominant CTL and VN antibody epitopes reside on FIV Gag proteins and envelope glycoproteins, respectively (Lombardi et al, 1993;Egberink et al, 1994;Flynn et al, 1995). These viral proteins also make up over 75% of the structural proteins and contain the major epitopes for immunodiagnostics.…”