Study On Subcutaneous Immunization Effect Of Live Vaccine Against PRRS

Porcine blue ear disease,also known as porcine reproductive and respiratory syndrome(PRRS),is a acute and highly pathogenic infectious porcine disease caused by porcine reproductive and respiratory syndrome virus(PRRSV).Since it was first reported in 1987,the disease has caused great economic losses to all countries and regions of the world so far.PRRSV is common in China,and the Ministry of agriculture of China lists PRRS as a kind of compulsory immunization disease.In view of this disease,it is very important to do a good vaccination.However,different methods of immunization shows different effects on the immune effect of pigs.The tracking analysis of effect of swine PRRS vaccine after subcutaneous immunization and muscle immune,was conducted,to understand the difference of immune effect caused by different injected methods and different PRRS vaccine dose,and further provide guidance of immune methods to farmers,and help farmers to save the cost of immunization.In this study,25 healthy unimmunized piglets of 21 days of age,which were tested for virus negative and average antibody close,were divided into 5 groups,to treat with subcutaneous and intramuscular inoculation of PRRS vaccine.The prevena cava aseptic blood sampling was carried out in 0,14 and 28 d.The serum and total blood samples of pigs were tested by ELISA and flow cytometry,respectively.And fluorescent quantitative PCR method was used to detect the specific antibody level,the percentage of T cell subsets and the PRRSV nucleic acid in blood and then analysed the changing rules of the corresponding indexes.The results showed that the level of antibody in 0.5 parts of the injection was higher than that of 0.25 parts of the subcutaneous injection and 1 parts of the subcutaneous injection;With the increase of time,the percentage of CD3+ in the blood of piglets with 0.5 parts of the subcutaneous injection was not significantly changed;Only 0.25 parts of the subcutaneous injection could increase percentage of CD4+ after vaccination which finally showed a downward trend as time goes on.The percentage of CD8+ in the blood of 0-28 d of pigs with subcutaneous injection was higher than that of intramuscular injection of 1 parts and other doses of subcutaneous injection,and the percentage of CD8+ in the blood of piglets in subcutaneous injection group was higher.The percentage of CD4+/ CD8+ in the blood of piglets under subcutaneous injection of 0.5 groups continued to decline,and the other groups were with the trend of first rise and fall.The virus nucleic acid is not detected in the blood after vaccination with PRRS attenuated vaccine.This study shows that for the same immune effect,the PRRS attenuated vaccine subcutaneous dose only needs half of the intramuscular injection dose.It also shows the difference between subcutaneous injection and the intramuscular injection of the PRRS vaccine.The PRRS vaccine used in the experiment is safe,and the nucleic acid of the virus is not detected in the blood after inoculation.It will not produce viremia after inoculation.It provides a useful basis for the saving of the PRRS vaccine cost for the large pig farmers.