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Data from S. Baize et al provide new insights into lassa virus

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"We followed virological, pathological, and immunological markers associated with fatal and nonfatal Lassa virus infection of cynomolgus monkeys. The clinical picture was characterized by fever, weight loss, depression, and acute respiratory syndrome. Transient thrombocytopenia and lymphopenia, lymphadenopathy, splenomegaly, infiltration of mononuclear cells, and alterations of the liver, lungs, and endothelia were observed. Survivors exhibited fewer lesions and a lower viral load than nonsurvivors. Although all animals developed strong humoral responses, antibodies appeared more rapidly in survivors and were directed against GP(1), GP(2), and NP. Type I interferons were detected early after infection in survivors but only during the terminal stages in fatalities. The mRNAs for CXCL10 (IP-10) and CXCL11 (I-TAC) were abundant in peripheral blood mononuclear cells and lymph nodes from infected animals, but plasma interleukin-6 was detected only in fatalities. In survivors, high activated-monocyte counts were followed by a rise in the total number of circulating monocytes. Activated T lymphocytes circulated in survivors, whereas T-cell activation was low and delayed in fatalities. In vitro stimulation with inactivated Lassa virus induced activation of T lymphocytes from all infected monkeys, but only lymphocytes from survivors proliferated," wrote S. Baize and colleagues.

The researchers concluded: "Thus, early and strong immune responses and control of viral replication were associated with recovery, whereas fatal infection was characterized by major alterations of the blood formula and, in organs, weak immune responses and uncontrolled viral replication.."

Baize and colleagues published their study in the Journal of Virology (Early and Strong Immune Responses Are Associated with Control of Viral Replication and Recovery in Lassa Virus-Infected Cynomolgus Monkeys. Journal of Virology, 2009;83(11):5890-5903).

For more information, contact S. Baize, Institute Pasteur, UBIVE, IFR Bioscience Gerland Lyon Sud 128, 21 Av Tony Garnier, F-69365 Lyon 7, France.

Publisher contact information for the Journal of Virology is: American Society Microbiology, 1752 N St. NW, Washington, DC 20036-2904, USA.

Keywords: France, Lyon, Biotechnology, Hematology, Hemorrhagic Fever, Infectious Disease, Lassa Fever, Lassa Virus, Lymphadenopathy, Lymphopenia, Splenomegaly, Thrombocytopenia, Tropical Disease, Vaccines, Viral Load, Virology, Weight Loss.

This article was prepared by Virus Weekly editors from staff and other reports. Copyright 2009, Virus Weekly via NewsRx.com.