Mapping B lymphocytes as major reservoirs of naturally occurring latent equine herpesvirus 5 infection.

This research investigates Equine herpesvirus 5 (EHV5), a common horse-infecting virus, and identifies B lymphocytes (a type of white blood cell) as the primary site for the virus’s latent (inactive) presence.

Research Background

• The researchers delve into Equine herpesvirus 5 (EHV5), a frequently observed gammaherpesvirus that affects horses globally.
• The biology and pathogenesis of this virus are not well-studied, with current understanding primarily formed on correlations with a closely related virus, EHV2.
• Gammaherpesviruses, like EHV5, survive long-term by creating latent infections in specific cells and tissues, especially lymphocytes (a kind of white blood cell).
• Latent virus infections are usually marked by a minimal number of genes active within the infected cell or tissue.

Research Methodology

• The researchers adopted an in vitro co-culturing technique to detect EHV5’s presence in horse peripheral blood mononuclear cells (PBMCs) and identify the primary cellular site for establishing and maintaining a latent infection.
• This included the isolation of PBMCs from 10 horses and dividing these into subpopulations, separated into T lymphocytes (CD4 and CD8 types), B lymphocytes, and macrophages.
• Each of these fractions was checked for latent EHV5 by co-culturing with equine fetal kidney cells.

Research Findings

• The researchers found a significantly increased number of plaques (an indication of virus presence) in the B lymphocyte enriched fraction, whereas a significant reduction was seen in B lymphocyte depleted fractions.
• These results suggest that equine gammaherpesviruses create latency in equine PBMCs, with the virus’s primary latent site being B lymphocytes.

Research Significance

• These findings enhance our understanding of EHV5’s behavior and its latency strategies.
• This knowledge can be crucial for further research in understanding gammaherpesvirus infections in general and devising strategies to manage and control them.