腺病毒於禽流感M2疫苗發展之評估

Abstract

一般商業化之家禽流行性感冒病毒之疫苗對於不同HA亞型之家禽流行性感冒病毒感染無交叉保護力。因此，本實驗以發展具交叉保護之疫苗為目的，利用複製缺陷腺病毒 (replication deficient adenovirus) 作為載體，建構帶有不同亞型間保守度高之M2基因片段的重組腺病毒 (Ad/M2)，再將Ad/M2免疫雞隻。Ad/M2感染之293A細胞及轉導之Vero細胞以間接螢光免疫分析皆有陽性訊號產生。在Ad/M2免疫雞隻的實驗結果顯示，補強後2週CD4+及CD8+ T cell相較於初次免疫有顯著增加；抗M2特異性抗體則於初次免疫後2週有顯著增加，但補強後的抗體上升效果則不明顯。於攻毒後第4天及第7天採集的喉頭拭子之real time RT-PCR結果顯示免疫組與對照組之間的AIV含量沒有差異，而攻毒後免疫組與對照組死亡率分別為40%及33.3%，給予Ad/M2之組別並無法對抗AIV感染。

Current vaccines to avian influenza virus can’t induce broad cross-protection against different subtypes. Therefore, the purpose of this research was to develop a vaccine which can confer cross-protection by using replication-deficient adenovirus as a vector to construct a recombinant adenovirus carrying highly conserved M2 gene (Ad/M2). The immunofluorescence assay revealed positive signal in 293A and Vero cells transduced with Ad/M2. The Ad/M2 was intranasally and intramuscularly immunized in chickens twice at a 4-week interval. Anti-M2 specific antibody was significantly higher after two weeks post primary vaccination. Challenging with AIV after two weeks post boost vaccination, the consequence of real time RT-PCR revealed AIV content was no difference between Ad/M2 group and control group in oropharyngeal swab on day 4 and day 7 post challenge. The mortality of Ad/M2 group and control group was 40% and 33.3% respectively. The conclusion is giving chickens Ad/M2 couldn’t confer protection against AIV infection.