A review of vaccine development and research for industry animals in Korea

Lee, Nak-Hyung; Lee, Jung-Ah; Park, Seung-Yong; Song, Chang-Seon; Choi, In-Soo; Lee, Joong-Bok

For examples, a single inoculation of VLP vaccine expressing HA and M1 proteins of AIV subtype H9N2 elicited a high level of HI antibodies and lowered the frequency of virus isolation after challenge with a virulent virus [28] , indicating http://www.ecevr.org/ http://dx. doi.org/10.7774/cevr.2012.1.1.18 that VLP vaccine would be a promising vaccine candidate against AIV. Similarly, immunization of VLP vaccine against HPAI was able to protect chickens from lethal challenge of wild type HPAI H5N1 virus [30] . Non-infectious recombinant pentamer-like structures of the FMDV were generated by expressing the gene for the P1 and 3C proteins whose expressions were under the control of individual promoters in the baculovirus expression system [44] . They were structurally similar to the authentic pentamer subunit from FMDV under the electron microscope. Immunization with such VLP into mice elicited high level of FMDV specific antibody. For swine vesicular disease virus (SVDV), a highly contagious disease of pigs, SVDV-like particles were generated by simultaneous expression of both P1 and 3CD proteins of SVDV, which resemble (both antigenically and morphologically) the authentic virus particles. The VLP may be used for a vaccine candidate against SVDV [45] . The orf 2 gene of PCV2 was cloned and inserted into the baculovirus expression system. The recombinant protein of ORF2 was formed to be VLP in infected insect cells [15] . As an attempt to create a novel vaccine against for porcine encephalomyocarditis virus (EMCV) causing reproductive failure in pregnant sows, a plasmid containing P12A and 3C genes of EMCV was generated and transfected into baculovirus expression system. Immunization of the VLP mixed with an alum adjuvant demonstrated the induction and maintenance of high level of neutralizing antibody and led to high protection efficacy after challenge with a wild type virus [46, 47] . For PRRSV, VLP expressing M and N proteins was generated in baculovirus expression system, and immunized into mice in order to evaluate its ability of inducing PRRSVspecific immune responses. According to unpublished data from our laboratory, PRRSV-VLP elicited strong immune responses as well as proper neutralizing antibodies against PRRSV, suggesting that VLP representing M and N proteins would be a potential vaccine candidate against PRRSV.