Preparation And Immunigenicity Of Porcine Circovirus2and Haemophilus Parasuis Combination Inactivated Vaccine

Porcine circovirus2(PCV2) is the main causative agent of postweaning multisystemic wasting syndrome(PMWS). Haemophilus parasuis(HPs) is the etiological agent of Glasser’s disease. The prevalence of Porcine circovirus2(PCV2) and Haemophilus parasuis (HPs) coinfection has caused great economic losses in pig industry. Vaccination is the major method to prevent and control the outbreaks of the diseases. Several vaccines are commercially available, but PCV2and HPs combination vaccine has not been developed.Structural protein encoded by PCV2ORF2can induce a high level of antibody and provide immune protection to pigs. In this study, the inactivated PCV2virus and recombinant capsid(BCap) protein expressed in baculovirus expression system were mixed with inactivated HPs5strain, respectively. The safety and immune efficiency of the two combination vaccine were evaluated in pigs.BCap (4mg/mL) and inactivated PCV2virus (105.0TCID5o/mL) were mixed with inactivated HPs5strain(5×10CFU/mL) and GEL-adjuvant to prepared combination vaccines. Thirty-five,28-day-old, healthy piglets were randomly divided into four treatment groups:pigs vaccinated with either BCap/HPS5vaccine(n=10) or iPCV2/HPs5vaccine(n=10), positive controls(n=10) and negative controls(n=5). At day28, all groups except negative controls were challenged with HPs5(2×109CFU/mL) or PCV2SH (105.0TCID5o/mL), and were necropised at day14,28days of challenging, respectively. Blood samples were collected from all pigs at arrival and14,28,42,56days post-vaccination, then were tested for ELISA antibody. As evaluated by seroconversion, clinical signs(fever), relative daily weight gain, viremia, and gross lesions. The results were:①All vaccinated pigs seroconverted to PCV2or HPs at28days post-vaccination.②After challenged with PCV2and PRRSV, the average rectal temperature of pigs in challenge control group was higher than that of vaccinated groups; the positive average weight growth was observed in all groups, the relative daily weight gain(RDWG) in vaccinated groups was similar to that in negative control group (P>0.05), but higher than that in challenge control group; At14days post-challenge, the amounts of PCV2DNA in serum samples in the challenge control group was significantly (P<0.05) higher than that of vaccinated groups; PCV2in lymphoid nodes was detected by Real-time PCR, the viral load in vaccinated groups were similar, and significantly (P<0.05) lower than that in challenge control group; the gross lesions and microscopic lesions in vaccinated groups were milder than those in challenge control group.③After challenged with HPs5, the average rectal temperature of pigs in challenge control group was higher than that of vaccinated groups; the RDWG in vaccinated groups was similar to that in negative control group (P>0.05), but higher than that in challenge control group; the gross lesions and microscopic lesions in vaccinated groups were similar and milder than those in challenge control group.The study indicated that BCap/HPS5and iPCV2/HPs5combination vaccine could induce immune response in pigs, and could prevent pigs from PCV2, HPs infection and provide some protection to pigs.