Expression of late viral proteins is restricted in nasal mucosal leucocytes but not in epithelial cells during early-stage equine herpes virus-1 infection.

The research study analyzed the expression of the late-stage proteins of the Equine Herpes Virus (EHV)-1 in different cell types during the early stages of infection. It was found that all the late-stage viral proteins were expressed in infected epithelial cells, but their expression was limited in infected leucocytes.

Background

• The study focusses on the Equine herpes virus (EHV)-1 that primarily invades the epithelial cells of the upper respiratory tract but can also spread to the tissue layer (lamina propria) and reach the bloodstream through infected mononuclear cells.

Methodology

• The research involved an analysis of the expression of late viral proteins namely, gB, gC, gD, and gM in respiratory epithelial cells and mononuclear cells.
• This was achieved through a three-fold approach: In vitro infection of epithelial-like rabbit kidney cells and peripheral blood mononuclear cells with EHV-1; Use of an equine ex vivo nasal explant system; And examination of nasal mucosa tissue from ponies infected in vivo.

Findings

• The viral proteins were fully expressed in all late-infected epithelial cells. However, their expression was found to be limited in infected leucocytes, the white blood cells involved in the immune response.
• More specifically, gB and gM proteins were expressed in 60-90% of infected leucocytes, and gC and gD proteins were expressed in just 20% of infected cells.

Conclusion

• The results from this study highlighted that the expression of these viral proteins during the early-stage EHV-1 infection greatly depends on the type of cell that gets infected.
• Epithelial cells showed a full expression of the late-stage proteins, while leucocytes displayed limited expression, underscoring the diverse impact of EHV-1 on different cellular hosts and hence, possibly contributing to the latency of this virus.