Epitope mapping of the V3 domain of feline immunodeficiency virus envelope glycoprotein by monoclonal antibodies

Neutralization sensitivity and accessibility of continuous B cell epitopes of the feline immunodeficiency virus envelope

“…This domain, SU2, is located in the V3 region of the SU glycoprotein, which has previously been shown to be sensitive to neutralizing antibodies, as assessed with laboratory-adapted strains during infection of CrFK fibroblasts (Lombardi et al, 1993;de Ronde et al, 1994) but not a lymphoid cell line (Lombardi et al, 1995). We confirm and extend these results in demonstrating that antibodies directed against this region also neutralize the infectivity of primary virus for a more natural cellular target, activated feline PBMC.…”

“…Similar results were obtained with FL-4 cells (data not shown). The accessibility of this domain is likely to be only partial: of antibodies elicited by a V3 peptide, polyclonal feline antibodies but not monoclonal antibodies labelled intact infected cells (Lombardi et al, 1993(Lombardi et al, , 1995. Temperature did not appear to influence the apparent degree of epitope exposure, as incubation of FL-4 cells with primary antibody at 4 °C or 37 °C had little effect on fluorescence intensity (data not shown).…”

“…The peptide SU2-0~, however, considerably inhibited neutralization mediated by monospecific antibodies directed against the SU2 domain. This 17 amino acid peptide derived from the FIVwo sequence is perfectly conserved in the 22 amino acid FIVpet~l .... peptide (V3-3) used to induce neutralizing feline sera (Lombardi et al, 1994) and monoclonal antibodies (Lombardi et al, 1995). While inhibition of anti-SU2 was marked even at a concentration of 0.25 gM (residual neutralization of 16%), neutralization mediated by serum from an experimentally infected cat was only modestly inhibited (residual neutralization of 80 %) even at the highest concentration (25 gM) of SU2-~.…”

Most Potential Linear B Cell Epitopes of Env Glycoproteins of Feline Immunodeficiency Virus Are Immunogenically Silent in Infected Cats

“…The env gene of FIV shows sequence diversities among different isolates that cluster in discrete segments known as variable (V) regions. Eight or possibly nine such V regions have been identified in FIV.3-6 In FIV Env glycoproteins three possible domains directly or indirectly involved in FIV neutralization have been described: two in the regions V4 and V5 of gp95, as shown by the fact that amino acid substitutions in these domains conferred resistance to virus neutralization,7" and the third in the V3 region spanning amino acidS 366C_C417 10,11 By the use of recombinant proteins or peptides, other antibody-binding sites have been mapped on SU and TM molecules. Pancino et al}2 by screening a random peptide library, identified five regions of the SU glycoprotein that were recognized by variable proportions of infected cat sera; one region appeared to be isolate specific while the others were more or less extensively broadly reactive.…”

Feline Immunodeficiency Virus Neuropathogenesis: From Cats to Calcium

“…FIV infection results in the synthesis of neutralizing antibodies that are targeted to various envelope domains with variable loop 3 and the carboxy terminus of envelope consisting of major antigenic sites (de Ronde et al 1994;Lombardi et al 1995;Richardson et al 1996). As with HIV-1, the cross-reactivity of sera for various FIV strains is highly variable (de Ronde et al 1994;Del Mauro et al 1998;Hohdatsu et al 1997;Osborne et al 1994;Richardson et al 1996) and specific mutations can confer resistance (Siebelink et al 1995).…”