Epidemiological Investigation Of Porcine Viral Diarrhea And Detection Of Its Antibody Against Vaccine

Porcine epidemic diarrhea virus(PEDV),Porcine transmissible gastroenteritis virus(TGEV)and Porcine rotavirus(PoRV)are the three main pathogens that caused porcine virus diarrhea.The main clinical symptoms of infected piglets were diarrhea,vomiting,and dehydration.Due to the strong infectivity and high mortality rate,it caused incalculable economic losses to the pig breeding industry,which greatly hampered the Development of the pig industry.This study investigated the prevalence of PEDV,TGEV and PoRV in Fujian Province in 2017 and Evaluated the immune effects of different combinations of swine viral diarrhea vaccines to Provides technical reference for the prevention and control of porcine virus diarrhea.Investigation of the prevalence of PEDV,TGEV and PoRV in Fujian Province:RT-PCR was used to detect the pathogens of 178 samples collected from 110 swine farms suspected of porcine virus diarrhea in Fujian Province,2017 were results showed that:(1)The positive rate of PEDV was highest 59.6%(106/178),while the positive of TGEV and PoRV was relatively low incidence.The positive detection rates were 7.3%(13/178)and 5.6%(10/178)respectively;2)The positive rates of PEDV in different regions from high to low:Ningde(75.0%),Longyan(70.4%),Chenzhou(65.2%),Nanping(60.0%),Sanming(58.3%),Fuzhou(58.0%),Quanzhou(46.2%),and Putian(45.0%).The positive rate of TGEV was:Sanming(16.7%),Longyan(11.1%),Putian(10.0%),Fuzhou(8.0%),Quanzhou(7.7%),Nanping(4.0%),Ningde(0.0%)and Chenzhou(0.0%).The positive rate of PoRV was:Putian(10.0%),Nanping(8.0%),Longyan(7.4%),Fuzhou(6.0)%),Sanming(0.0%),Quanzhou(0.0%),Ningde(0.0%)and Chenzhou(0.0%);(3)The porcine viral diarrhea could mainly be found in winter and spring,the positive rate of PEDV were 63.9%and 57.1%,the positive rate of TGEV were 9.7%and 8.9%,and the positive rate of PoRV were 5.6%and 8.9%respectively;(4)The onset of viral diarrhea in piglets were mainly within 7d and 7d?25d.The positive rate of PEDV were 73.13%and 57.78%,the positive rate of TGEV was 8.96%and 8.89%,and the positive rate of PoRV was 8.96%and 6.67%,respectively.Evaluation of porcine viral diarrhea vaccine combination:30 gilts with similar gestational age were randomly divided into 5 test groups and 1 control group.The existing commercially available PEDV,TGEV,and PoRV classic strain triple-attenuated vaccines(attenuated CV777+Attenuated China virus strain+NX strain),PEDV,TGEV classical strain double-attenuated vaccine(ZJ08 strain+HB strain)and PEDV,TGEV variations Two strains of inactivated vaccine strains(AJ1102 strain +WH-1 strain)were used to perform a combination of two or two vaccines.The experimental groups were gaven the first inoculation at 40days before giving birth and the second at 20days before giving birth,while the control group was immunized with the same dose of physiological saline.The serum levels of PED-IgG,TGE-IgG and PoR-IgG in the sows at Id,21d,35d and 49d after the first immunization were measured.The results showed that:(1)The PED-IgG total antibody level in serum of the sows immunized with the combination of "two-combined attenuated live vaccine + two-combined inactivated vaccine",with better equilibrium degree,is higher than other combinations of the vaccines.The growth and decline law of the antibody level at the stage after immunization of 1?21d,21?35d and 35?49d has the tendency of“rising,rising and falling”.(2)There was no significant difference between the TGE-IgG total antibody levels in serum after immunization with the combination of the"two-combined attenuated live vaccine + two-combined inactivated vaccine" and the combination of the“triple-attenuated live vaccine +two-combined inactivated vaccine ",but higher than other vaccine combinations.The combination of the " two-combined attenuated live vaccine + two-combined inactivated vaccine" was superior to that of the" triple-attenuated live vaccine + two-combined inactivated vaccine" by comparing the equilibrium degree of the two antibody levels.(3)The total antibody level of PoR-IgG in serum was higher than that of other vaccine combinations after immunizing sows with "triple-attenuated live vaccine + triple-attenuated live vaccine ".The growth and decline law of the antibody level presented on days 1d?21d,21d?35d and 35d?49d after immunization was "rising,rising and falling".Conclusions:(1)The investigation of epidemic situation of swine viral diarrhea in Fujian province indicated that the pathogen of swine diarrhea in swine farms in large-scale pigs in Fujian province is mainly swine epidemic virus(PEDV).(2)The immunization of sows with the vaccine combination of " two-combined attenuated live vaccine +two-combined inactivated vaccine" and“triple-attenuated live vaccine+ triple-attenuated live vaccine" resulted in higher serum antibody levels with better equilibrium degree.