Endemic Lassa fever in Liberia. III. Characterization of XXXX isolates.

@entity1 @entity840 @entity26211
Sixty-three virus isolates were obtained by inoculation of Vero cells with sera from 50 hospital in- @entity1 in Liberia with acute febrile illnesses. 57 of the isolates were presumptively identified as @entity26211 (LV) by direct fluorescent antibody (DFA) staining of inoculated Vero cells. These, and six additional isolates obtained only by titration of supernatant fluids from inoculated Vero cells, were definitively identified as LV in a neutralization test. Two additional LV isolates were obtained from a @entity1 's sera from Nigeria. By cross-neutralization tests, the Nigerian LV strains were serologically identical to the prototype Nigerian LV strain (PP) but were distinct from both a reference LV strain from Sierra Leone (SL), and from the Liberian (LIB) strains isolated in this study. The LIB and SL strains were closely related to each other, but not to the Nigerian LV strains. LIB LV strains were tested for virulence in strain 2 and 13 @entity840 , and a spectrum of virulence was observed which correlated only approximately with disease severity for @entity1 @entity1 . Two @entity1 -lethal isolates killed all inoculated strain 2 and 13 @entity840 , whereas nine isolates from mildly ill @entity1 were benign for @entity840 . Yet some LV isolates from severely ill or lethally infected @entity1 , especially those from pregnant @entity1 and @entity1 , were totally benign for @entity840 . These data suggest that antigenically distinct LV strains exist in nature, and that antigenically indistinguishable LV isolates may differ in virulence potential for various hosts.
