ANTIGENICITY AND IMMUNOGENICITY OF EQUINE INFLUENZA VACCINES CONTAINING A CARBOMER ADJUVANT

Equine influenza vaccines containing inactivated whole virus and Carbo mer adjuvant stimulated higher levels and longer lasting antibody to h aemagglutinin in ponies than vaccines of equivalent antigenic content containing aluminium phosphate adjuvants. Five months after the third dose of vaccine containing Carbomer adjuvant, ponies were protected ag ainst clinical disease induced by an aerosol of virulent influenza vir us (A/equine/Newmarket/79, H3N8). In contrast ponies which received va ccine containing aluminium phosphate adjuvant were susceptible to infe ction and disease. There was an inverse correlation between prechallen ge levels of antibody detected by single radial haemolysis (SRH) and d uration of virus excretion, pyrexia and coughing. All ponies with anti body levels equivalent to SRH zones of greater than or equal to 154 mm (2) were protected against infection and all those with levels greater than or equal to 85 mm(2) were protected from disease.