| In order to investigate porcine Pseudorabies infected wild virus situation in the large-scale hoggeries,In the first experiment ,we did a serological testing for PRV infected wild virus among different batches of serum from 15 provinces'69 large-scale hoggeries in China using PRV gE antibody ELISA kit. The results were shown that 936 of 3466 serum were positive,the average positive rate of serum is 27%; and the positive rate in Guangxi and Shanghai are the highest among the 15 provinces, is 65% and 64% respectively, positive rate in Guangdong is the lowest, only is 1%, in the other provinces range from 4%～44%. It is shown that Pseudorabies infected wild virus in many hoggeries is widerspread.In addition, infected proportion between the whole swinery and seed swinery was shown a obvious positive correlation relationship in many hoggeries.As to the current state of immune control in China, when the immune porcine were infected with porcine Pseudorabies virus, wild-virus is usually not infectious to the embryo through placenta, and can only attack the upper respiratory tissue.Immune porcine can reduce the amount of wild-virus elimination, 1000 times less than non-immune porcine at least; Expulsion period of toxin may be shortened by 4～7 times. However, wild-virus infected porcine Pseudorabies can be incubate in the trigeminal ganglia and so on, when the porcine only receives influence of each factor in vivo and outside, porcine Pseudorabies virus can be activated to breed and eliminate toxin . It is the basic reason that continuing high level of positive rate for porcine Pseudorabies wild-virus infection in the immunity swinery. However, If people want to control and the purify Pseudorabies, they must try to prevent or reduce latent wild-virus infection (vaccination does not prevent or reduce latent Pseudorabies virus infection). Therefore, we carried out the second experiment: Seed swinery of large-scale hoggeries that is implementing the immunity purification plan(seed swinery implement the entire group immunity, all the back-up swinery selected for negative of pseudorabies wild-virus), what does change and differ from wild-virus infection rule, (According to theory, It is calculated that the reserve swinery is a negative of pseudorabies wild-virus, seed swinery replace and insist immunity through 2～3 year, proportion of seed swinery infected with wild-virus Should be decreased substantially, but fact was not true),The result has made us feel very surprised: Infection proportion of brood sow group have a gradual increase along with the birth rank increases, The more infection proportion of stock boar group increased, the higher and faster sow seed group infected the proportion of Pseudorabies virus along with the birth rank increases, This is no doubt to illustrate that sow seed group infected Pseudorabies wild-virus is closely related the numer of breeding, that is to say, (wild-virus infection) is closely related to the spread of semen. Then Porcine Pseudorabies's purification program should have some adjustments in large-scale hoggeries: Puts boar swinery's purification to plants seed swinery purification first (This can be completely done in any hoggeries, and It is certain time-gap that it is based on laboratory track). Afterward, we consider the back-up swine options; finally, we consider multiparity sow swinery.The purpose of the third and fourth experiment is to investigate the relationship of the infection rate of pseudorabies between seed swinery and ware swinery in large-scale pig farm and to test the Pseudorabies purification program of some large-scale hoggeries. From the experiment one it's known that, in natural conditions (no systematic Pseudorabies purification program was taken), there is a correlation relationship in the infection rate of Pseudorabies wild-virus infection between ware swinery and seed swinery. However, with the different immunization program of purification, this phenomenon has been different:the rate of Pseudorabies wild-virus infection is high in Some seed swinery, but the ratio is not high in ware swinery or even no infection, Oppositely, the rate of Pseudorabies wild-virus infection is not high in Some seed swinery, but the ratio is high in ware swinery.This phenomenon tells us: there is no necessary relationship between the infection rate of Pseudorabies wild-virus infection between ware swinery and seed swinery. Just some of the immune purification program is different. One is intranasal immunization of breast-feeding pigs early (0～15 days)+intramuscular injection of conservation period (7～10 weeks) (although the rate of Pseudorabies wild-virus infection is high in seed swinery, but it's low in ware swinery). The other is not intranasal immunization,but intramuscular injection of an immune in breast-feeding or conservation period (4～8 weeks).Although we have done a lot of experiments, research that has also been a number of new knowledge and added for porcine Pseudorabies wild-virus's purification program of large-scale porcine farms, but it,s also far from over. The performance is concentrate on: Does not boar semen contain the virus under highly immune state (for instance: 3 times a year)? What does the mechanism and the way infect sow? After intranasal immunization of ware swinery in the early, what principle can resist infection's pressure? The fifth experiment studied that several hoggeries have not made serum and semen of boar group of Pseudorabies wild-virus purification large-scale hoggeries (only immunize GE gene deletion of the attenuated vaccine). The seminal fluid adopted PCR examinal methods for examining Pseudorabies virus, the serum adopted PCR and ELISA examinal methods for examining separately Pseudorabies virus and the Ge antibody. Through observation of the existence status of the pseudorabies virus in boar semen and the existence of pseudorabies virus in serum, whether confirmed the existence of each other and the state of the actual infection (gE antibody). |
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