The Immune Efficacy Of Inactivated Pseudorabies Vaccine JS-2012-â–³gI/gE

According to the sequences of the gB gene of pseudorabies virus(PRV), a pair of primers and a TaqMan probe were designed for development of a real-time fluorescence quantitative PCR(qPCR) assay allowing for the rapid, sensitive, and specific detection of PRV DNA. The qPCR assay was capable of detecting at least 10 copies/ul DNA, which was 100 times more sensitive than the conventional PCR. There was not any cross-reactivity with other related virus, such as classical swine fever virus(CSFV), porcine reproductive and respiratory syndrome virus(PRRSV) and porcine circovirus type 2(PCV2) indicating that the assay was highly specific to PRV. The coefficient of variation, less than 1%, showed a good stability of the assay. Therefore, the qPCR assay was a valuable tool for rapid detection and quantification of PRV classical or variant strains.In order to determine the minimum dose of the inactivated swine Pseudorabies vaccine(JS-2012-△gI/gE strain), twenty five 2-week-old piglets free of PRV antibodies were randomly assigned to five groups of five each and housed separately. Group 1, 2, 3 and 4 were vaccinated intramuscularly(i.m.) with 0.5 mL, 1 mL, 2 mL and 3 mL of inactivated swine Pseudorabies vaccines(JS-2012-△gI/gE strain) respectively and the booster inoculation was performed at 28 days post first inoculation. Group 5 served as uninoculated control. Sera of all piglets were collected weekly from 1 to 8 weeks post inoculation for PRV gE and gB antibodies. At 28 days post-inoculation(d.p.i.), all piglets were challenged intranasally(i.n.) with 105.0 TCID50 of PRV JS-2012 strain. Following the challenge, clinical signs and rectal temperatures were recorded daily for 14 days. The results showed PRV gB antibodies become positive in group 2-4 at 14 d.p.i. while the gB antibodies become positive in group 1 at 21 d.p.i. In the group 1, four out of five piglets showed no typical clinical signs of PR but a fever for 3 to 5 days while one out of five piglets showed depression, anorexia and mild neurological symptoms after challenge. In the group 2-4, all piglets showed no typical clinical signs of PR but a fever for 3 to 5 days after challenge and no pathological lesions. In the group 5, all piglets showed a high fever(above 41℃), obvious depression, anorexia and neurological symptoms after the challenge, two piglets died at 6 and 7 days post challenge respectively, and severe pathological lesions such ashemorrhage in the brains and lungs. According to the above results, the minimum dose of the vaccines was 1 mL per piglets.In this study the mice model was used to evaluate the effect of the inactivated PR vaccine(JS-2012-△gI/gE strain). Six-week-old KM mice were randomly assigned to five groups. Group 1, 2, 3 and 4 were vaccinated subcutaneously(s.c.) with 0.05 mL, 0.1 mL, 0.2 mL and 0.3 mL of inactivated swine Pseudorabies vaccines(JS-2012-△gI/gE strain) respectively(n=10) and the booster inoculation was performed at 28 days post first inoculation. Group 5 served as uninoculated control(n=5). At 21 d.p.i., all mice were challenged subcutaneously(s.c.) with 50 LD50 of PRV JS-2012 strain. Following the challenge, clinical signs were recorded daily for 21 days. The results showed three mice in the group 1 and two mice in the group 2 died at 3-4 days post challenge(d.p.c.) while the mice in the group 3 and group 4 were all survival. All mice in the control group died at 3-4 d.p.c. The above immune-challenge experiments in mice were performed again. DNA was extracted from organs of mice(five out of ten mice in every group) for virus detection by the real-time PCR. The results showed all mice in the group 1-4 survived with a few or no virus nucleic acids in some organs after challenge while all mice in the control group died at 3-5 d.p.c. with a large number of virus nucleic acids. There were some differences about the protection rate between two ecxperiments, which may associate with precision of the operation in injection or challenge. In general, higher immune dose of inactivated PR vaccine showed higher protection rate to mice, which was consistent with the results of immune-challenge experiments in pigs. Therefore, it is feasible to evaluate the effect of inactivated PR vaccine(JS-2012-△gI/gE strain) using mice model.