Antigenic characterization of rabies virus isolates from vaccinated dogs in plateau state, Nigeria.

Rabies isolates (genotype 1 lyssaviruses) from vaccinated dogs that died of rabies infection in the Plateau area of Nigeria were characterized using monoclonal antibodies (MAbs). The isolates were examined for rabies (genotype 1) and rabies-related (genotypes 2, 3 and 4) viruses by the indirect fluorescent antibody test carried out with MAb 502-2, which recognizes the nucleocapsid protein of all known lyssaviruses, and with MAb 422-5, which identifies only rabies-related viruses. All three isolates showed positive immunofluorescence with MAb 502-2 and were negative with MAb 422-5, indicating that they were all rabies (genotype 1) viruses. Characterization with a panel of 36 anti-nucleocapsid monoclonal antibodies showed that all three isolates reacted positively with 35 of the anti-nucleocapsid MAbs, including MAb 102-27 and MAb 377-7. Characterization using a panel of 44 anti-glycoprotein MAbs differentiated the isolates sharply from LEP Flury and PM vaccine viruses. The pattern of anti-glycoprotein reactivity of the isolates showed them to belong to one distinct viral subtype, except for a minor variation in one isolate that was not neutralized by MAb 1101-3. None of the three isolates was identified as the Flury low egg passage (LEP) vaccine strain used for vaccinating dogs in Nigeria. In fact, all the three isolates had the typical pattern of reactivity of isolates from unvaccinated dogs, including MASS 83, a rabies virus isolated in Nigeria and characterized at the Wister Institute before this study.