Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Oct 31;83(11):1694-1701.
doi: 10.1292/jvms.21-0350. Epub 2021 Sep 14.

Establishment of a mouse- and egg-adapted strain for the evaluation of vaccine potency against H3N2 variant influenza virus in mice

Enkhbold Bazarragchaa  1 , Takahiro Hiono  1 , Norikazu Isoda  1   2 , Hirotaka Hayashi  1 , Masatoshi Okamatsu  1 , Yoshihiro Sakoda  1   2
Affiliations

Establishment of a mouse- and egg-adapted strain for the evaluation of vaccine potency against H3N2 variant influenza virus in mice

Enkhbold Bazarragchaa et al. J Vet Med Sci. .

Abstract

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.

Keywords: H3N2 variant; adaptation; influenza; mouse model; vaccine.

PubMed Disclaimer

Conflict of interest statement

The authors have nothing to disclose.

Figures

Fig. 1.
Fig. 1.
Growth kinetics of Ind/08/11 (H3N2)v viruses in chicken embryos. The viral growth was assessed using three chicken embryos inoculated with viruses of 102.0 50% tissue culture infective dose (TCID50) per 0.1 ml for 72 hpi. The viral growth was quantitatively indicated by TCID50 in Madin–Darby canine kidney (MDCK) cells (A) and by hemagglutination (HA) titer using chicken red blood cells (B) at each time point. The blue line and dash-dotted red line represented Ind/08/11 and Ind/08/11 ma-P7/e-P3, respectively. Asterisk indicated a significant difference between the Ind/08/11 and Ind/08/11 ma-P7/e-P3 groups (P<0.05) at each time point.
Fig. 2.
Fig. 2.
Virus recovery of Ind/08/11 (H3N2)v viruses from mice after serial passages. Lungs of mice inoculated with Ind/08/11 or Ind/08/11 ma-P7/e-P3 were collected at 3 dpc. Virus titers of each mouse lungs were expressed as dots, and the average virus titer in the group are indicated with bars. The dashed line indicates the lower detection limit of virus titration (101.8 50% tissue culture infective dose (TCID50) per gram). Asterisk showed the significant difference (P<0.05) under the hypothesis that the titer below than lower limit is set as 101.8 TCID50/g, which may provide the highest significant titer in the group.
Fig. 3.
Fig. 3.
Virus recovery from the lungs of immunized mice after the challenge. Five mice in each vaccine-dose group were challenged with 105.0 50% tissue culture infective dose (TCID50) per 30 µl of the homologous strain, Ind/08/11 ma-P7/e-P3, after two times of subcutaneous vaccination with 4, 20, and 100 µg of the vaccine strain, as well as without antigen (Phosphate Buffered Saline (PBS)), respectively. Viruses in the lungs were titrated from the mice in each group at 3 dpc. Virus titers of individual lung samples were expressed as dots, and the geometric mean of virus titers in the group is shown with the bar. The dashed line indicates the lower detection limit of the virus titration (101.8 TCID50/g). Asterisk indicated the significant difference (P<0.05) under the hypothesis that the titer below than lower limit is set as 101.8 TCID50/g, which may provide the highest considerable titer in the group.
Fig. 4.
Fig. 4.
Body weight changes of immunized mice after virus challenge. Five mice in each vaccine-dose group were challenged with 105.0 50% tissue culture infective dose (TCID50) per 30 µl of the homologous strain, Ind/08/11 ma-P7/e-P3, after two times of subcutaneous vaccination with 4, 20, and 100 µg of the vaccine strain, as well as without antigen (Phosphate Buffered Saline (PBS)), respectively. Body weight of the mice was monitored daily for 14 days after the challenge. An average of the body weight proportion on each post-challenge day to day 0 was indicated with open (no challenge) or closed points with lines (vaccinated in different doses). In the figure, α, β, and γ indicate the significant difference from the PBS group to the 100-, 20-, or 4-µg dose groups (P<0.05), respectively.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

  • Trivalent mRNA vaccine-candidate against seasonal flu with cross-specific humoral immune response.
    Mazunina EP, Gushchin VA, Kleymenov DA, Siniavin AE, Burtseva EI, Shmarov MM, Mukasheva EA, Bykonia EN, Kozlova SR, Evgrafova EA, Zolotar AN, Shidlovskaya EV, Kirillova ES, Krepkaia AS, Usachev EV, Kuznetsova NA, Ivanov IA, Dmitriev SE, Ivanov RA, Logunov DY, Gintsburg AL. Mazunina EP, et al. Front Immunol. 2024 Apr 16;15:1381508. doi: 10.3389/fimmu.2024.1381508. eCollection 2024. Front Immunol. 2024. PMID: 38690272 Free PMC article.

References

    1. Barman S., Franks J., Turner J. C., Yoon S. W., Webster R. G., Webby R. J.2015. Egg-adaptive mutations in H3N2v vaccine virus enhance egg-based production without loss of antigenicity or immunogenicity. Vaccine 33: 3186–3192. doi: 10.1016/j.vaccine.2015.05.011 - DOI - PMC - PubMed
    1. Caldera F., Mercer M., Samson S. I., Pitt J. M., Hayney M. S.2021. Influenza vaccination in immunocompromised populations: Strategies to improve immunogenicity. Vaccine 39 Suppl 1: A15–A23. doi: 10.1016/j.vaccine.2020.11.037 - DOI - PubMed
    1. Centers for Disease Control and Prevention.2020. How influenza (Flu) vaccines are made? https://www.cdc.gov/flu/prevent/how-fluvaccine-made.htm [accessed on June 7, 2021].
    1. Chien C. Y., Xu Y., Xiao R., Aramini J. M., Sahasrabudhe P. V., Krug R. M., Montelione G. T.2004. Biophysical characterization of the complex between double-stranded RNA and the N-terminal domain of the NS1 protein from influenza A virus: evidence for a novel RNA-binding mode. Biochemistry 43: 1950–1962. doi: 10.1021/bi030176o - DOI - PubMed
    1. European Medicines Agency.2017. Guidence on influenza vaccine −Quality module. https://www.ema.europa.eu/en/documents/scientific-guideline/guideline-in... [assessed on Aug 16, 2021].