Immunofluorescence studies on the antigenic interrelationships of the Hughes virus serogroup (genus Nairovirus) and identification of a new strain.

Titrations of hyperimmune antisera by indirect immunofluorescence using each virus of the Hughes serogroup (Hughes, Zirqa, Punta Salinas, Soldado and Farallon) demonstrated their individual antigenic identities. Furthermore, an antigenically related virus, designated Puffin Island (PI) virus, was shown both by indirect immunofluorescence and by neutralization in XTC cells to be distinguishable from the other viruses. These viruses readily established persistent infections in Vero cells after producing only moderate cytopathic effects. Treatment of persistently infected cultures with either fluorodeoxyuridine or bromodeoxyuridine made no significant difference to the percentage of immunofluorescent cells. Attempts to demonstrate haemagglutination by Zirqa virus were unsuccessful.