Isolation And Epidemiological Survey Of The ORF In Yangling And Genes Analyzed By Bioinformatics

Orf also know as contagious pusrular dermatitis virus(CPDV) and scab mouth, is causedby orf virus (ORFV), which is a kind of acute, contagious and infectious disease. Goats aresusceptible to infection, but lambs are more susceptible due to incomplete immune system.Goats can be repeated infected by ORFV, due to it has immune escape mechanism. Recentyears, goat industry was developing rapidly in our country, orf had been one of the diseaseswhich is very important to goat industury. There are many questions about orf research, first,the virus must be isolated from scabs or tissues with clinical symptom; second, there haven’t adetailed epidemiological investigation data; third, little is know about the genes which haverelationship with virulent and immune escap mechanism.The study was conducted for diary goats, which were raised in three goat farms locatedin Yangling Shaanxi Province. Anticoagulated blood, cotton swabs and whey were collected,DNA were extracted by NaI or GuSCN buffer methods and then detected by PCR using F1Lprimers. One strain of orf virus was isolated from whole blood of clinically normal but viruspositive goat at BTs, was identified by CPE, PCR and phylogenetic analysis. Bioinformaticsanalysis were conducted on the gene ORFV121and vIL-10of ORFV-FX0910betweenvirulent ORFV and low virulent ORFV. Here are the results.1. The results of epidemiological investigation indicated that, in the A goat farm, thepositive rate of blood, cotton swabs and whey were21.25%,25%and16.12%separately; inthe B goat farm, the positive rate of blood and cotton swabs were27%and8.1%separately;in the C goat farm, the positive rate of blood, cotton swabs and whey were34.23%,18%and30.63%separately.2. Blood of clinically normal but virus positive goat inoculated into primary BTs afterbeen handled, and the CPE can be observed after3blind passages. The BTs showingcharacteristic rounding, ballooning, and increased refractility post-infection. PCR products ofB2L and VIR were analyzed, specific bands can be seen at1100bp and550bp; phylogeneticanalysis indicated that the virus has a close relationship with ORFV-India strain and Greecestrain，means that the virus was ORFV and named as ORFV-YL.3. The results of bioinformatics analysis shows that: there was a glutamic deletion at site118of ORFV121in the lvORFV, which suggested the corresponding base mutation was significant. As a result, hydrophilicity and secondary structure were changed, and antigenicitywas changed essentially at many domains of the ORFV121protein. For vIL-10protein, therewere5amino acid mutations (14: Vâ†'W,49: Aâ†'P,57: Tâ†'M,72: Râ†'C,79: Iâ†'V) and onetryptophan insertion at site79, which resulting the variations of hydrophilicity, secondarystructure, and antigenicity.Conclusion:1. The pathogen positive rate of goats in these farms is not optimistic, viruscan be secreted into environment by oral secretions and milk, the risk of break out of orf inthese farms is very high.2. This is the first report about detected ORFV in whey.3. This study find a kind of new methord and materials for virus isolation，the research ofORFV viology and epidemiologic studies were promoted.4. There are gene mutations between vORFV and lvORFV.