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| Safety and Immunogenicity of the Recombinant Adenovirus Expressing the GP5 and M Protein of PRRSV in Piglets |
| ZHANG Zhi-tao;LI Yu-feng;JIANG Ping; TANG Jing-yuan;ENG Yu-xiu;DONG Xin-tian;LI Jun-xing |
| Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, Nanjing Agriculture University,Nanjing 210095, China |
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Abstract In order to study the safety and immunogenicity of recombinant Adenoviruses expressing GP5(rAd-GP5) and M protein(rAd-M) of Porcine reproductive and respiratory syndrome virus (PRRSV), Forty-seven 30-day-old post-weaning PRRSV-negative piglets were vaccinated with the viruses and bred respectively for clinical observation, virus shedding test and immune examination. The results were as following: (1) The piglets vaccinated with rAd-GP5 and rAd-M showed no significant clinical syndrome, and blood, nasal scraping, faecal samples and pen environment were all negative against PRRSV and parental Adenovirus by RT-PCR. (2) The PRRSV specific antibody titers in piglets, which vaccinated with rAd-GP5, rAd-M, rAd-GP5+M (rAd-GP5/rAd-M, V/V=1), PRRSV-Resp strain, and no inoculation, respectively, were examined at different time post immunization. The results indicated that PRRSV specific antibody could be detected by ELISA and neutralization assay 14 and 45 days post vaccination. In groups of rAd-GP5 and rAd-M, the titer of ELISA antibody were more than 1∶2400 at day 60 and 90 post vaccination, which were similar to that of piglets inoculated with PRRSV-Resp vaccine. However, the neutralizing antibody titers in the two groups of rAd-GP5 and rAd-M were less than 1∶6, which were lower than that of PRRS-Resp group, from 60 to 90 days post vaccination. Furthermore the level of ELISA antibody to PRRSV in piglets vaccinated with both rAd-GP5 and rAd-M were more than that of piglets vaccinated with singlerAd-GP5 or rAd-M. (3) Following challenge with virulent strain of PRRSV-S1 at 28 days post vaccination, no significantly temperature variation of the immunized pigs was observed. The time of viremia and virus shedding in piglets vaccinated with recombinant Adenoviruses were only 2 weeks, which were shorter than that of control piglets with no vaccine. And the titers of PRRSV specific ELISA antibody and neutralizing antibody were enhanced in piglets vaccinated with rAd-GP5 or rAd-M post challenge. The results suggest that rAd-GP5 and rAd-M are safe to piglets and can elicit good protective immune responses corporately.
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Received: 15 July 2005
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Corresponding Authors:
JIANG Ping
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