Actinobacillus pleuropneumoniae: An Update on Epidemiology, Biovar, Serotyping, Virulence, and Laboratory Diagnosis.

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia, a highly contagious respiratory disease. It is classified into two biovars on the basis of NAD requirement for growth: biovar 1 (NAD-dependent) and biovar 2 (NAD-independent). Biovar 1 consists of 17 serovars (1-12 and 15-19) and biovar 2 has 8 serovars (2, 4, 7, 9, 11, 13, 14, and 17). Several virulence factors are responsible for the pathogenesis of A. pleuropneumoniae, particularly Apx toxins, capsular polysaccharides, lipopolysaccharides, and membrane proteins. In this review, the current knowledge of biovars, serovars, epidemiology, virulence factors of A. pleuropneumoniae as well as laboratory diagnosis and vaccines are summarized.