Isolation Of Orf Virus From Weihai Stain And Kunming Strain And Virulence Of Attenuated Research

Orf（Contagious ecthyma）, also known as contagious pustule. Orf is caused by orfvirus, orf virus is the member of parapoxvirus. Usually the virus is spread bythe scab. Environmental is polluted by materials to spread the virus. The morbidity of thedisease is high, but the mortality is low. Typically, the mortality of lamb is high. Theincidences of clinical manifestations of sheep were found in Weihai and Kunming.And swelling, blisters, papules, scab have been observed on the lips of lambs. Therefore,scabs were collected from the farms. Orf viruses were isolated and identificated in this study.The orf virus of Shandong strain and orf virus of Yunnan strain were passaged toweaken virulence, preparation of the attenuated strains, the strains were determined by safetytest, and the antibody titers were determined. Research contents and results are as follows.The virus strain was isolated from crust materials of lambs with orf like-clinicalsymptoms from a goat farm in Weihai city of Shandong province by passage in primarybovine testicular cells (PBTC). The virus was identified as orf virus using cell morphology oflesions, TCID50test and PCR method. The results showed that PBTC cultures infected withcrust materials displayed cytopathic effects at the fifth passages. The titer of the sixthpassages virus was106.5TCID50/mL. The specific orf virus B2L gene was amplified. Theresults suggested that, Cells condensation, turned round and necrosis rupture fall off; the virustiter of the6thgeneration was106.5TCID50/mL; The fragments were the size of540bp, TheWeihai strain and Kunming strain were isolated and identified successfully.The identified orf virus of Weihai strain and Kunming strain were passaged on calf testiscells until the85generations. The virus titers of85th generation were measured. The lips ofone month lambs were inoculated with this two attenuated orf viruses. Then the adultmale rabbits were inoculated with the attenuated orf viruses for the preparation of antibody.The results suggested that: Shandong strain and Yunnan strain of virus titers were107.5TCID50/mL and107.6TCID50/mL; Observation found that the wound healed in third day, andno any other pathology. The conclusion is that Orf virus of Shandong and Yunnanwere attenuated successfully; the antibody titers of Orf virus of Shandong and Yunnan were 105and106from ELISA. Orf virus Shandong strain and Yunnan strain of antibody titerswere measured by neutralizing antibody test is1:43and1:37.The results: Firstly, Orf virus of Weihai strain and Kunming strain were isolated andidentified successfully; Lastly, Weihai strain and Kunming strain were attenuatedsuccessfully.