development of first mannheimia haemolytica vaccine candidate in iran

Pneumonic mannheimiosis (pasteurellosis) in sheep and cattle is caused by m. haemolytica agent which attributed to a number of infections in domestic and wild animals. m. haemolytica adapted to colonize and persist on respiratory muco sal surfaces of sheep, cattle, and other ruminants and avoid host safety responses. based on capsular antigen typing m. haemolytica subdivided into thirteen a serotypes. different studies indicated that m. haemo lytica biotype a, specially serotypes 1, 2 and 6, are by far the most important and commonly isolated bacterial patho gen in development of pneumonic pasteurellosis or shipping fever. management of mannheimiosis involves the use of antimicrobial drugs and vaccines. m. haemolytica vaccines should be able to produce an effective immune response that would kill m. haemolytica and neutralize lkt, decrease lung colonization, prevent escape of host defense mechanisms. however, diagnosis of serotypes is the main step in the control of m. haemolytica infection and provides useful information for developing suitable vaccine strategies to prevent pneumonic pasteurellosis, but there is little information about the serotype profile of field isolates of m. haemolytica in iran. in this research, 362 lung and nasal samples from sick domestic animal were detected by culture and pcr methods. totally, 71 m. haemolytica isolates were identified in three main serotypes (a1, a2, and a6). serotypes a2 (38/71؛ 54%) and a1 (25/71؛ 39%) were the most frequently detected, whereas the a6 serotype was detected with a frequency of less than 1% (1/71؛ 1%) and 7 isolates remained unknown (7/71؛ 10%). subsequently, m. haemolytica vaccinal strain was developed and then formalin-killed vaccine was prepared. it provided the best protection against mannheimiosis in sheep which was proved by indirect elisa.