Study On Application Of Polymerase Chain Reaction In Diagnosis Of Canine Common Infectious Disease

PCR technique was developed in 1980s of 20th century. A specific DNA fragment can be amplified by enzyme in vitro. It has specific, sensitive, rapid, simple advantage. Specific DNA fragment can be amplified by 10~5～10~9 times. Expected size DNA band of PCR products can be seen by agarose gel electrophoresis, thus the pathogen genome fragment was identified. This paper mainly studies on application of Polymerase Chain Reaction in diagnosis of Canine Distemper, Canine Parvovirus infection, Canine Adenovirus infection and Canine Babesiosis.According to the genome sequences of pathogen in GenBank, specific primers were designed to amplified specific fragment of RNA or DNA in clinical pathological samples by RT-PCR or PCR technique. PCR products were identified by agarose gel electrophoresis or polyacrylamide gel electrophoresis, then PCR products were further analysised by semi-nested PCR, restriction fragment length polymorphism or sequence analysis. Finally an accurate diagnosis of the disease was made.Application the semi-nested RT-PCR method for diagnosis of Canine Distemper, a 586bp gene fragment was amplified in the first round of PCR and a 476bp gene fragment was amplified in the second round of PCR. Among 29 clinical pathological samples, there are 19 positive samples. Application the PCR and sequence analysis method for diagnosis of Canine Parvovirus, a 448bp gene fragment was amplified by specific primers. It suggests that there are 19 positive samples, among 29 clinical pathological samples. Application the PCR-RFLP and sequence analysis method for diagnosis of Canine Adenovirus and Canine Babesiosis, it suggests that there are 5 cases of Infectious Canine Hepatitis and 3 cases of B.gibsoni infection. Application the multi-PCR method for diagnosis ofcanine parvovirus and canine adenovirus at the same time, the result suggests that there is no case of mixed infection.Initial clinical detection results prove that PCR method can rapidly and accurately diagnose Canine Distemper, Canine Parvovirus infection, Canine Adenovirus infection and Canine Babesosis, but also further identify the type of pathogens.