Analysis of efficacy obtained with a trivalent inactivated Haemophilus parasuis serovars 4, 5, and 12 vaccine and commercial vaccines against Glässer's disease in piglets.

The objective of this study was to assess the efficacy of a trivalent inactivated Haemophilus parasuis serovars 4, 5, and 12 vaccine with polymeric adjuvant gel (GEL) and commercial vaccines against Glässer's disease in piglets. Commercial vaccines containing inactivated H. parasuis serovars 4 and 5 (China), inactivated H. parasuis serovars 1 and 6 (Spain), and inactivated H. parasuis serovar 5 (USA) were also evaluated. Our results demonstrated that the trivalent inactivated H. parasuis serovars 4, 5, and 12 vaccine with GEL adjuvant can provide better protection against the 3 most common pathogenic serovars circulating in China than other commercial vaccines tested. Our findings also indicated that inactivated H. parasuis serovars 1 and 6 vaccine cross-protects piglets against H. parasuis serovars 4 and 5; inactivated H. parasuis serovar 5 vaccine cross-protects piglets against H. parasuis serovar 4 challenge; but none of the commercial vaccines tested in this study protected piglets against H. parasuis serovar 12. Our results provide a basis for further identification of common protective antigens that can induce cross-protection against heterogeneous serovars.