Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan.
International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan.
J Vet Med Sci. 2021 Oct 31;83(11):1694-1701. doi: 10.1292/jvms.21-0350. Epub 2021 Sep 14.
Sporadic spreads of swine-origin influenza H3N2 variant (H3N2v) viruses were reported in humans, resulting in 437 human infections between 2011 and 2021 in the USA. Thus, an effective vaccine is needed to better control a potential pandemic for these antigenically distinct viruses from seasonal influenza. In this study, a candidate vaccine strain with efficient growth capacity in chicken embryos was established through serial blind passaging of A/Indiana/08/2011 (H3N2)v in mice and chicken embryos. Seven amino acid substitutions (M21I in PA; A138T, N165K, and V226A in HA; S312L in NP; T167I in M1; G62A in NS1 proteins) were found in the passaged viruses without a major change in the antigenicity. This mouse- and egg-adapted virus was used as a vaccine and challenge strain in mice to evaluate the efficacy of the H3N2v vaccine in different doses. Antibodies with high neutralizing titers were induced in mice immunized with 100 µg of inactivated whole-virus particles, and those mice were significantly protected from the challenge of homologous strain. The findings indicated that the established strain in the study was useful for vaccine study in mouse models.
猪源 H3N2 流感病毒（H3N2v）在人类中的零星传播已被报道，在美国，2011 年至 2021 年期间有 437 例人类感染。因此，需要一种有效的疫苗来更好地控制这些与季节性流感具有不同抗原性的潜在大流行病毒。在本研究中，通过在小鼠和鸡胚中对 A/印第安纳/08/2011（H3N2）v 进行连续盲传，建立了一种在鸡胚中具有高效生长能力的候选疫苗株。在传代病毒中发现了 7 个氨基酸替换（PA 中的 M21I；HA 中的 A138T、N165K 和 V226A；NP 中的 S312L；M1 中的 T167I；NS1 蛋白中的 G62A），但抗原性没有发生重大变化。该经小鼠和鸡蛋适应的病毒被用作疫苗和攻毒株，在小鼠中评估不同剂量的 H3N2v 疫苗的效果。用 100µg 灭活全病毒颗粒免疫的小鼠产生了高中和滴度的抗体，这些小鼠对同源株的攻毒有明显的保护作用。研究结果表明，本研究中建立的株系可用于小鼠模型中的疫苗研究。
