Investigation Of Wild Pseudorabies Virus Infection In Large Scale Pig Farms In Shandong Province And Safety Production Measures For Positive Pig Farms

Pseudorabies(PR),also known as Aujeszky's Disease(AD),is a severe infectious disease caused by the infection of Pseudorabies Virus(PRV)in various domestic and wild animals such as pigs,cattle and sheep Is an important epidemic that seriously harms the global pig industry.In the context of the existence of African swine fever,the price of pigs has skyrocketed,although China has always been committed to the purification of pseudorabies,and domestic large-scale pig farms are reluctant to eliminate wild poisonous infected sows,and many pig farms convert ternary commercial pigs into Sow feeding,which greatly increases the number of positive PRV gE antibodies.In order to explore the block of PRV transmission of commercial pigs through optimization of immunization procedures and strict biological safety measures,the safe production of commercial pigs on PRV wildpositive breeding farms can be achieved.In order to explore the block of PRV transmission of commercial pigs through optimization of immunization procedures and strict biological safety measures,the safe production of commercial pigs on PRV wild-positive breeding farms can be achieved.First of all,the PRV infection status of some large-scale pig farms in Shandong Province was collected from 5038 sera from various stages of large-scale pig farms in different regions of Shandong,and the PRV gE antibodies of different pig populations in large-scale pig farms in various regions of Shandong Province in 2018 were tracked..The test results showed that the number of gE antibody positives was 2267,the overall positive rate was 45.00%;among them,the sows with more than 6 parities had the highest gE antibody positive rate,70.09%;followed by 3-4 parity sows,the positive rate was 59.14%;The lowest positive rate was fattening pigs at 16 weeks of age,with a positive rate of 18.99%.This indicates that there are widespread PRV infections in pig farms of various regions in Shandong Province,and the pressure of PRV infection is greater.In this study,a binary sow farm with all sows PRVgE antibodies positive and all boars PRVgE antibodies negative was selected as the test site.The pathological examination of suspected cases and histopathological observations of the test site showed the pathological changes of typical PR cases.The virus isolates a strain of PRV virus,named "SD-H";through gE gene sequencing,homology analysis with the reference sequence shows that the SD-H strain has less nucleotideand amino acid homology with European and American strains,and it has The nucleotide and amino acid homology of the strain is high;the SD-H strain is found to be a mutant strain by establishing a genetic evolution tree.The positive rate of gE antibody in the sows produced in this farm was 100%.The daily abortion test found that 4.5% of abnormal sows detoxified,accounting for 0.05% of the large herd;while the testicular fluid of suckling piglets was found to be about Vertical transmission of PRV occurred in 4.16% of the litters,which was basically the same as the detection of the tainted blood of cord blood in the test batch.The sows and newborn piglets with positive antigens were excluded from the herd and separated and raised.Adopt a two-point production method to implement reasonable vaccine immunization and biological safety measures at all stages of the production of sows,boars,suckling piglets and nursery and finishing pigs.By isolating antigen-positive pigs,adjusting and optimizing immunization procedures and strict biological safety measures,although the commercial piglets produced by PRVgE antibody-positive sow herds are all positive for PRVgE antibodies in the early stage due to maternal antibodies.However,from 30 days to 160 days of age,PRVgE antibodies gradually become negative,and they can be free from PRV wild poison infection in commercial pigs.This shows that the optimization of immunization procedures and strict biological safety measures can block the infection of PRV by commercial pigs,so that this batch of commercial pigs will eventually be released in a negative state.