Kang Yong-Myung, Cho Hyun-Kyu, An Sung-Jun, Kim Hyun-Jun, Lee Youn-Jeong, Kang Hyun-Mi
Animal and Plant Quarantine Agency, 177 Hyeoksin 8-ro, Gimcheon-si 39660, Korea.
Vaccines (Basel). 2022 Nov 3;10(11):1860. doi: 10.3390/vaccines10111860.
Since 2018, Korea has been building an avian influenza (AI) national antigen bank for emergency preparedness; this antigen bank is updated every 2 years. To update the vaccine strains in the antigen bank, we used reverse genetics technology to develop two vaccine candidates against avian influenza strains belonging to clades 2.3.2.1d and 2.3.4.4h, and then evaluated their immunogenicity and protective efficacy in SPF chickens challenged with H5 viruses. The two vaccine candidates, named rgCA2/2.3.2.1d and rgES3/2.3.4.4h, were highly immunogenic, with hemagglutination inhibition (HI) titers of 8.2−9.3 log2 against the vaccine strain, and 7.1−7.3 log2 against the lethal challenge viruses (in which the HA genes shared 97% and 95.4% homology with that of rgCA2/2.3.2.1d and rgES3/2.3.4.4h, respectively). A full dose of each vaccine candidate provided 100% protection against the challenge viruses, with a reduction in clinical symptoms and virus shedding. A 1/10 dose provided similar levels of protection, whereas a 1/100 dose resulted in mortality and virus shedding by 7 dpi. Moreover, immunity induced by the two vaccines was long lasting, with HI titers of >7 log2 against the vaccine strain remaining after 6 months. Thus, the two vaccine candidates show protective efficacy and can be used to update the AI national antigen bank.
自2018年以来，韩国一直在建设用于应急准备的禽流感国家抗原库；该抗原库每两年更新一次。为了更新抗原库中的疫苗毒株，我们利用反向遗传学技术研发了两种针对2.3.2.1d和2.3.4.4h分支禽流感毒株的候选疫苗，然后在感染H5病毒的SPF鸡中评估它们的免疫原性和保护效力。这两种候选疫苗分别命名为rgCA2/2.3.2.1d和rgES3/2.3.4.4h，具有高度免疫原性，针对疫苗毒株的血凝抑制（HI）效价为8.2−9.3 log2，针对致死性攻击病毒的HI效价为7.1−7.3 log2（其中HA基因与rgCA2/2.3.2.1d和rgES3/2.3.4.4h的HA基因分别具有97%和95.4%的同源性）。每种候选疫苗的全剂量均可提供100%的攻毒保护，临床症状和病毒排泄减少。1/10剂量可提供相似水平的保护，而1/100剂量在攻毒后7天导致死亡和病毒排泄。此外，两种疫苗诱导的免疫持久，6个月后针对疫苗毒株的HI效价仍>7 log2。因此，这两种候选疫苗显示出保护效力，可用于更新禽流感国家抗原库。
