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

Inactivated vaccines are safer than live vaccines because they cannot replicate at all in a vaccinated host, resulting in no risk of reversion to a virulent form capable of causing diseases. However, they generally provide a shorter length of protection than live vaccine and generally elicit weak immune responses, in particular cell-mediated immunity, as opposed to live viral vaccines. For this reason, inactivated vaccines are administered with potent adjuvant, and require boosters to elicit satisfactory and a long-term immunity. Vaccines of this type are generally created by inactivating propagated viruses by treatment with heat or chemicals such as formalin or binary ethyleneimine. This procedure can destroy the pathogen's ability to propagate in the vaccinated host, but keeps it intact so that the immune system can still recognize it. Although inactivated virus vaccines have been used for preventing various types of viral diseases over the decades, they need further development for controlling newly emerging diseases. For examples, influenza virus vaccines are continually improved to contain all serotypes because many new serotypes emerge in new outbreaks. As with other approaches, many studies have been focused on searching for better adjuvants which enhance immune responses in accordance with inactivated vaccines [14] as well as help to overcome the inhibitory effects of maternal antibody. For live AIV vaccines, the possibility of reassortment between live vaccine strain and field isolates and of back mutation from low-pathogenic to highly pathogenic viruses lead to serious concerns for vaccine safety. Thus, prior stimulation of the immune system using some immunomodulators followed by vaccination with inactivated vaccines may be needed to confer better http://www.ecevr.org/ http://dx.doi.org/10.7774/cevr.2012.1.1.18 protective immunity within a short period of time and may be promising in controlling LPAI H9N2 [12] .