Human B cells: newly described targets for hantavirus infection

KLINGSTRÖM J; MALEKI K; MARTINEZ V; GARCÍA M; SCHIERLOH P; IGLESIAS A

St Raphael

Encuentro; 8th European Meeting on Viral Zoonoses; 2017

The European Society For Virology

Hantavirus are enveloped RNA viruses belonging to the Bunyaviridae family. They are classified as Old World and New World hantaviruses. The first are responsible for Hemorrhagic Fever with Renal Syndrome (HFRS), mainly in Europe and Asia whereas the latter are responsible for Hantavirus Pulmonary Syndrome (HPS) in the Americas. The main known target of infection are microvascular endothelial cells. In previous studies, we observed a massive polyclonal activation of circulating B cells in HPS patients from Argentina and an increased risk for B cell lymphoma development related to HFRS history in Sweden. This led us to question if these cells may constitute alternative targets for hantavirus infection. To test this hypothesis, purified B cells from healthy blood donors (n=9) were exposed to HTNV, ANDV and PUUV strains at a MOI of 1. Supernatants and cells were then collected at different timepoints. To asses for infection, cells were lysed for western blot detection of the nucleocapsid protein (NP) or processed for immunofluorescence detection of intracellular NP by confocal microscopy. To test for productive infection, supernatants were assayed for production of focus forming units. Additionally, B cells were co-cultured with HTNV infected endothelial cells (HUVEC, 3dpi) for 24hs and activation markers were analyzed on B cells by flow cytometry. In vitro assays showed that B cells are susceptible to infection by both Old World and New World hantaviruses. Additionally, HTNV causes productive infectivity, as shown by increased progeny titers over time after infection. Furthermore, B cells showed increased levels of CD69 expression when co-cultured with infected endothelial cells, indicating activation upon co-incubation. These results indicate that human B cells constitute an alternative target for hantaviruses with secretion of fully functional infectious virions. This novel finding could entail B cell involvement in disease pathogenesis and thus, further studies are required.