Protective efficacy of a reverse genetics-derived inactivated vaccine against equine influenza virus in horses.

The research article presents a study examining the effectiveness of a newly developed vaccine, based on reverse genetics, in protecting horses from the equine influenza virus. The findings indicate that this new vaccine, derived using reverse genetics, has comparable efficacy to that of traditional vaccines created from wild-type viruses and supports the use of reverse genetics in updating equine influenza vaccine strains.

Research Methodology

• For the purpose of the research, a virus strain (A/equine/Tipperary/1/2019) was selected. Two versions of the virus, a wild-type (WT) version, and another created through reverse genetics (RG), were inactivated using formalin to prepare vaccines.
• The RG virus was generated using hemagglutinin and neuraminidase genes from the selected strain, combined with six other genes from a high-growth virus (A/Puerto Rico/8/34).
• Twelve horses, aged one year and without any existing antibodies against the equine influenza virus, were sorted into three groups: a control group, a group for WT vaccination, and a group for RG vaccination.
• The horses received two doses of their respective vaccines, four weeks apart, and were then exposed to the selected virus strain two weeks after the second vaccination.

Findings and Analysis

• The researchers monitored pyrexia (fever) and respiratory illness as indicators of infection. All horses in the control group and one in the WT group showed these symptoms for multiple days, while one RG vaccinated horse exhibited pyrexia but no respiratory illness.
• The mean rectal temperatures and concentrations of serum amyloid A (an inflammation marker) were significantly lower in the WT and RG groups compared to the control group, with no significant differences observed between the WT and RG groups.
• Both the WT and RG vaccines were found to greatly decrease viral shedding compared to the control group.

Conclusions

• The results suggest that the equine influenza vaccine developed using reverse genetics is as effective in protecting against the disease as a vaccine utilizing traditional wild-type viruses.
• The researchers concluded that the RG technique has potential in simplifying the process of updating equine influenza vaccine strains, proving to be a promising avenue for future vaccine developments.