Change of Antibody Isotypes in FMD-Vaccinated Sows and Piglets

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Department of Life Science, NTNU
口蹄疫為偶蹄類之一高度傳來病。臺灣於1997年爆發O1型口蹄疫病毒之後,所有豬隻皆注射口蹄疫疫苗。本研究乃要探討抗體isotypes在口蹄疫疫苗注射豬隻的變化以及母體移行抗體對疫苗注射仔豬之抗體isotypes產生的影響。為了探討抗體變化情形,在五個月期間於不同時間點採集二十頭疫苗補強注射過豬隻(A及B場各十頭)血清。同時自A及B場各十入頭一月齡仔豬在疫苗注射之前與之後收集血清。A場仔豬在三月齡時接受疫苗注射,而B場仔豬共接受兩次疫苗注射分別於二及三月齡時。對照、經血清樣品乃採自三十頭specific pathogen-free豬隻,以及自兩場三十頭注射過口蹄疫疫苗但尚未補強豬隻。使用口蹄疫病毒蛋白質(含有可被疫苗注射過豬隻血清抗體認識的13kD及66kD抗原)於本試驗。結果發現,接受疫苗注射且有補強豬 隻,其IgG1抗體量比沒補強注射者顯著增加。IgG2抗體只在A場豬隻有上升情形。和沒補強注射豬隻比較,IgA量在A、B兩場並沒顯著增加。A場豬隻IgM抗體維持一常值,且顯著比B場和沒補強注射豬隻高。沒補強注射豬隻比specific pathogen-free豬隻有較高的IgG1,IgG2及IgA量;而IgM抗體在此兩組並沒顯著差異。主要的母體移行抗體為IgG1和IgG2。血清IgG1及IgG2抗體只在接受兩次疫苗注射之仔豬顯著增加。然而,IgM和IgA量在接受一次或兩次疫苗注射之仔豬並沒顯著不同。
Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals. After the outbreak of serotype O1 FMD virus in Taiwan in 1997, pigs were extensively vaccinated. To investigate the development of antibody isotypes in response to FMD vaccine and the influence of maternally derived antibodies on the production of antibody isotypes in vaccinated piglets, sera were collected over a five month period from twenty vaccinated sows (from two farms) after they were boosted with the FMD vaccine. Sera were also collected from 18 one-month-old piglets from each before and after they were vaccinated. Piglets at farm A were vaccinated when they were three months old; those at farm B were vaccinated at both two and three months. As a control, serum samples were collected from 30 FMD virus-free pigs and 30 FMD vaccinated pigs without booster injection at two additional farms. We analyzed the FMD virus proteins, which contain the 66kD and 13kD antigens recognized by serum antibodies of vaccinated pigs, to find that the IgG1 antibody level increased significantly in vaccinated sows receiving booster injections. The IgG2 antibody was enhanced only in sows at farm A. The IgA levels at both farms were not significantly higher compared to sows without booster injections, but the IgM levels at farm A were constant, which was significantly higher than at farm B or among pigs with no booster. Pigs without booster injections had significantly higher IgG1, IgG2 and IgA levels than those of FMD virus-free pigs, but the IgM antibody levels did not differ. The maternally derived antibodies were IgG1 and IgG2. Serum IgG1 and IgG2 antibodies increased significantly only if piglets were immunized twice. However, the levels of IgM and IgA in piglets did not vary with frequency of vaccination.