Molecular Pathogeny Investigation Of ORF And The Immune Effect Assessment Of ORF Virus Inactivated Vaccine On A Goat Farm Located In Fuping County

Contagiouts Ecthyma (CE or orf) is a highly contagious disease which outbreaks in goatsbreeding areas all over China currently. CE greatly affects the health and ability of productionof adult goats and more importantly it influences the growth and development of lambsnegatively. So it has caused great economic loss to farmers. At present, there are little datasabout epidemiological survey, therapy or vaccine. In this study, an epidemiological surveywas accomplished in a goat farm located in Fuping County, Shaanxi province. Then aninactivated vaccine was prepared using the FX0910strain which seperated in our laboratory.After prepared, the safety and effect of the inactivated vaccine were evaluated. The marjorreseach contents, results and conclusions are as follows:1. Molecular pathogeny investigation of orf in the first farming community of guanzhongdairy goats in Fuping CountyIn this study, samples of blood and cotton pledget were abtained from apparent healthygoats and genomic DNA were extracted by the methods of NaI and GuSCN repectively. Thena multiplex PCR assay established in our laboratory was used to detect orf virus (ORFV). Theresults showed that the rate of ORFV carriers which including blood positive, cotton pledgetpositive and double positive were different among different colonies.The total rate of ORFVcarriers was66.36%and among them the single positive rates of blood and cotton pledgetsamples were58.49%and23.64%respectively, and the double positive rate was13.64%.2. Preparation of ORFV inactivated vaccine and evaluation of the immune effectThe virulent strain FX0910saved in our laboratory was proliferated on the bovinetesticular primitive cells and the virulence was confirmed by the method of Reed-Muenchafter the proliferation. Then the ORFV cultures was inactivated for48h with formaldehydewith a final concentration of0.4%and the inactivation effect was determined by inoculatingon bovine testicular primary cells and lips of lambs respectively. Then the inactivated ORFVcultures were adequately mixed with aluminium hydroxide adjuvant or transfer factor toprepare two different inactivated vaccines and the safeties of which were determined byinjecting subcutaneously in the groin of lambs with10times of normal dose. Pregnant goats were vaccinated with the two inactivated vaccines three times with a interval of14days viacervical subcutaneous injection, the immune doses were1ml per goat and2ml per goatrespectively. Blood and cotton pledget samples were collected before or after each vaccination.Then pathogens and titers of neutralization antibody were detected by the multiplex PCR andthe method of fixed virus concentration reacting with different serum dilutions. The morbidityof the newborn lambs was also calculated. The results were as follows:(1) ORFV wasproliferated on the bovine testicular primitive cells and its titer was determined as108.46TCID50/mL.(2) Inactivated ORFV could not induce cytopathic effect (CPE) or clinicalsymptoms on lambs, which showed that the virus had lost the virulence.(3) Lambs’ bodyconditions were well after inoculated with Orfv inactivated vaccine in groin, so the safety ofinactivated vaccine was been confirmed.(4) The rates of ORFV carriers were reduced from75%to40%or50%to16.67%after inoculated with aluminium hydroxide-or transferfactor-adjuvant inactivated vaccine once respectively, and and the rates were all reduced to0%after vaccinated twice. The titers of neutralization antibody in pregnant goats weresignificantly increased from1:2and1:20.49to1:24.5and1:24.75after inoculated with aluminiumhydroxide-or transfer factor-adjuvant inactivated vaccine three times respectively. Themorbidity of one-month-old lambs which vaccinated ORFV inactivated vaccines was20%,while35.48%of control.Conclusion:1. Obtained data for the prevalence of Orf about110goats in the first farming communityof guanzhong dairy goats in Fuping County.2. The ORFV inactivated vaccines were prepared successfully and confirmed safe.3. The results of the immune effect evaluation showed that the ORFV inactivatedvaccines were effective. The titers of neutralization antibody were increased remarkably, andto some extent, it was of therapy effect to remove pathogen.4. Newborn lambs could be protected well after the pregnant goats inoculated with ORFVinactivated vaccines.