Immunogenicity and protective efficacy of inactivated equine influenza (H3N8) virus vaccine in murine model.

The research article investigates the effectiveness of an inactivated equine influenza virus vaccine in providing protection against the disease when tested on a BALB/c mouse model. The vaccine shows promising results, with the mice exhibiting a strong antibody response and lesser signs of disease.

Overview of the Research

• The study aimed to assess the suitability of BALB/c mice as a potential model for preliminary tests of equine influenza (EI) vaccine candidates. It evaluated the immunogenicity (ability to provoke an immune response) and protective efficacy of an inactivated equine influenza virus (EIV, H3N8 strain) vaccine in these mice when exposed to the homologous H3N8 virus.

Methodology

• An inactivated H3N8 vaccine was administered to the BALB/c mouse model. After this, the mice were exposed to a viral challenge with the homologous H3N8 virus.
• Serological tests were performed to assess the immune response of the mice to the vaccine. This was done by evaluating antibody levels using a haemagglutination inhibition assay (HAI) and ELISA.
• Mice were also observed for clinical signs of infection, along with examination of gross and histopathology lesions for signs of damage due to the virus. Viral antigen distribution, viral replication, and virus detection in nasal washes were assessed for evaluating disease severity and viral spread.

Findings

• The vaccine induced an optimum protective antibody level on the 49th day post-infection, along with a balanced Th1/Th2 immune response. This suggested the vaccine’s ability to prompt an effective immune response.
• The immunized mice showcased better disease outcomes following EIV exposure. This was evident from less severe clinical signs of infection, lower gross and histopathological lesion scores, restrained virus replication in the respiratory tract, and reduced virus detection in nasal washes, indicating restricted viral spread.
• The duration of viral load in vaccinated mice was also shorter and for a brief period compared to the unvaccinated ones, suggesting the vaccine’s potential in controlling the disease progression.

Conclusion

• The research shows that the inactivated H3N8 vaccine effectively induces a specific antibody response and protects against the H3N8 virus in the BALB/c mice. It concludes that this vaccine could provide effective intervention against the equine H3N8 virus.
• It also suggests that BALB/c mice can be employed as models for preliminary testing of EI vaccines before they are trialed in horses. This could expedite the vaccine evaluation process and facilitate the development of effective vaccines against equine influenza.