RESUMEN
To complete our analysis of the E2 glycoprotein of Venezuelan equine encephalomyelitis (VEE) virus, we prepared six synthetic peptides corresponding to the extramembranal carboxy-terminal one-third of the protein. NIH-Swiss mice were immunized with the peptides, and antipeptide and antiviral titers were determined by enzyme-linked immunosorbent assay (ELISA). Challenge studies revealed that peptide 13 (amino acids 241-265) protected 60-70% of virus-challenged mice. Although the other peptides generally elicited antipeptide ELISA titers but no or low antiviral titers and did not protect mice, significant E2 reactivity was found in immunoblots. These results provide the first direct evidence that much of the E2 carboxy-terminal domain is cryptic in the VEE virion, even when virus was bound to polystyrene ELISA plates.
Asunto(s)
Virus de la Encefalitis Equina Venezolana/inmunología , Encefalomielitis Equina Venezolana/prevención & control , Fragmentos de Péptidos/inmunología , Proteínas del Envoltorio Viral/inmunología , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/sangre , Ensayo de Inmunoadsorción Enzimática , Femenino , Immunoblotting , Ratones , Vacunas Sintéticas/inmunología , Proteínas del Envoltorio Viral/químicaRESUMEN
A peptide composed of the amino-terminal 25 amino acids of the E2 glycoprotein of the virulent Trinidad donkey (TRD) strain of Venezuelan equine encephalomyelitis virus was found to protect peptide-immunized mice from lethal TRD virus challenge (Hunt et al., 1990). Viral growth in peptide-immunized animals was found to be limited in comparison to that in nonimmunized controls. Although both treated and control groups of mice responded to virus challenge by producing neutralizing antibody, only immunized mice with preexisting antipeptide antibody survived. Polyclonal antipeptide sera as well as a monoclonal antipeptide antibody were able to passively protect naive mice from TRD virus challenge, despite the fact that these antibodies were nonneutralizing. Passive transfer of antipeptide antibody to immunosuppressed recipients was not protective, thus indicating that survival of TRD virus challenge required an in situ immune response as well as preexisting antipeptide antibody. Binding studies of both polyclonal and monoclonal antipeptide antibodies indicated that they recognize only epitopes present on virus-infected cells or denatured virus.
Asunto(s)
Anticuerpos Antivirales , Virus de la Encefalitis Equina Venezolana/fisiología , Encefalomielitis Equina Venezolana/inmunología , Péptidos/síntesis química , Replicación Viral , Animales , Formación de Anticuerpos , Complejo Antígeno-Anticuerpo/análisis , Línea Celular , Virus de la Encefalitis Equina Venezolana/inmunología , Ensayo de Inmunoadsorción Enzimática , Epítopos/inmunología , Femenino , Técnica del Anticuerpo Fluorescente , Pruebas de Inhibición de Hemaglutinación , Caballos , Inmunización Pasiva , Inmunoglobulina G/análisis , Inmunoglobulina M/análisis , Ratones , Ratones Endogámicos , Péptidos/inmunologíaRESUMEN
Fourteen peptides representing 67% of the extramembranal domain of the Venezuelan equine encephalomyelititis (VEE) virus E2 glycoprotein were synthesized and analyzed to determine their antigenic, immunogenic, and protective capacities. Thirteen of 14 peptides elicited antibody for the homologous peptide. Thirteen peptides elicited antiviral antibody that recognized either the Trinidad (TRD) strain of VEE virus or the TC-83 vaccine derivative, or both. Two peptides, VE2pep01(TC-83) and VE2pep01(TRD), protected significant numbers of mice from TRD virus challenge. The majority of the peptides were reactive with antisera from mice immunized with the various subtypes of VEE virus. A competition assay using antipeptide antibodies to block virus binding of anti-VEE virus monoclonal antibodies corroborated previous studies on the spatial relationship of E2 epitopes and provided evidence for a spatial overlap of the E2 amino terminus with a domain composed of residues 180-210.