An Argentine equine herpesvirus strain with special restriction patterns protect mice challenged with a pathogenic strain.

Equine herpesvirus 1 (EHV-1) was first isolated in Argentina in 1979. This strain SPv has special restriction patterns, but a previous study demonstrated that SPv did not modify its growth in cell culture. In addition, it showed low virulence in the mouse respiratory model consistently with results found in female BALB/C at different state of gestation. This study evaluates in a mouse respiratory model, if primary infection with SPv strain protects animals from subsequent challenge with a pathogenic strain. Body weight loss was not observed in mice intranasally inoculated with SPv strain and challenged with HH1 Japanese strain. The SPv primary infection does not completely prevent clinical presentation by HH1 infection but the SPv inoculated animals recovered more quickly, with less intense and less persistent histological lesions. The challenge infection caused a rapid and prolonged increase in anti-EHV-1 antibodies in the mice previously infected with SPv, along with a more rapid reduction of viral titres in lungs. In this work it was demonstrated that this EHV-1 strain constitute a good immunogen. These results show that this SPv strain could be considered to produce an EHV-1 vaccine.