Table 2.

Methodological sensitivities of different LCMV detection methods evaluated with diluted virus stock and infected MC57 cells

Material tested	Detectable units	Detection limit per spleen
		Focus-forming assay	Nested NPRT-PCR	Transfer in AG 129 mice
Spleen + Dilutions of LCMV stock	pfu	104	102	0.2-1
Spleen + LCMV-infected MC57 cells	No. of infected MC57 cells	102	10-40	1-4

Increasing dilutions of a LCMV-WE stock (viral titer measured by focus-forming assay) or decreasing numbers of LCMV-infected MC57 cells were mixed with the equivalent of a quarter of spleen and the indicated three LCMV-detection methods (as detailed in Materials and Methods) were performed on these samples to evaluate the respective detection limits.