摘要：Mannheimia haemolytica causes mannheimiosis which renders significant economic losses for farmers and is one of the major diseases in the small ruminants of Pakistan. This bacterium is normal habitant in the nasopharynx and in case of stress establishes infection in the lungs of the small ruminants. As a result, adherence and proliferation of the organism will take place in the respiratory tract, causing tissue infections and inflammatory reactions which have significant contribution in the pathogenesis of mannheimiosis. The virulence factors of Mannheimia haemolytica include proteineous adhesions, capsular polysaccharide, outer membrane proteins, iron-binding proteins, lipopolysaccharide or lipooligosaccharide, enzymes, and toxins. These virulence factors induce severe inflammatory reactions and damage the immune system. Inflammatory cytokines play a significant role in the pathogenesis of pneumonic mannheimiosis andthe modulation of their expression may serve to reduce cellular changes in reproductive system of male goats. In mannheimiosis acute phase proteins increase in concentration during the acute phases and play a vital role in restoring homeostasis and reducing microbial growth in ruminants subjected to infection and stress which may affect male reproductive physiology, reduce the testosterone hormone and also the semen quality, and thereby, resulting in decreasing efficiency in breeding bucks. Little is known about the male goat's reproductive patho-physiology in relation with Mannheimia haemolytica. Therefore, this review article aims to shed light on the pathogenesis and virulence mechanism of mannheimiosis towards host cell responses focusing on the male goats in small ruminants.
