TABLE 2.

Virus-positive macrophages in vivo^a

Virus strain	% Virus-positive macrophages
	TMEVhi MacI+ cells	TMEVlo MacI+ cells	TMEV+ MacI− cells
DA	26 ± 3	21 ± 4	53 ± 1
R2	2 ± 1	82 ± 8	16 ± 6

^aThe mice were sacrificed 45 days after intracerebral inoculation. Viral and CD11b antigens were detected by immunofluorescence in frozen sections of longitudinal spinal cord. Nuclei were stained with 4′,6′-diamidino-2-phenylindole (see Fig. 6). The sections were scanned systematically, and virus-positive cells were recorded for their CD11b⁺ or CD11b⁻ phenotype and their TMEV hi or lo phenotype. TMEV^hi corresponds to cells with intense diffuse fluorescence; TMEV^lo corresponds to cells with faint punctate fluorescence. Values are means ± standard errors of the means.