TABLE 2.

Virus-specific T-cell responses in CD40L^−/− and (B6 × 129)F₁ mice^a

Day after infection	(B6 × 129)F1 mice				CD40L−/− mice
	% IFN-γ+ CD8+ cellsb		CD4+ Thp frequencyc		% IFN-γ+ CD8+ cells		CD4+ Thp frequency
	p56	p79	600 PFU	10,000 PFU	p56	p79	600 PFU	10,000 PFU
7	0.52 ± 0.18	0.42 ± 0.17	148 ± 21	ND	0.55 ± 0.07	0.49 ± 0.18	6,408 ± 4,973	ND
16	2.68 ± 0.86	4.87 ± 1.07	80 ± 68	128 ± 144	1.77 ± 1.00	2.80 ± 1.64	6,102 ± 6,982	3,234 ± 2,033
35	0.91 ± 0.15	1.67 ± 0.92	ND	ND	1.63 ± 0.62	4.03 ± 2.97	ND	ND

^aThe (B6 × 129)F₁ and CD40L^−/− mice were infected i.n. with 600 PFU of γHV-68, and single-cell spleen suspensions were analyzed for virus-specific CD8⁺ (p56 or p79) or CD4⁺ T (Thp) cells. All values are means ± standard deviations for four or five mice. ND, not done. 

^bDetermined by flow cytometric analysis of spleen populations following 6 h of stimulation with the H-2D^b-restricted p56 peptide or the H-2K^b-restricted p79 peptide in the presence of brefeldin A. The lymphocytes were fixed and stained for the presence of IFN-γ. 

^cReciprocal of the CD4⁺ Thp frequency, determined in a 48-h ELISpot assay. The Thp frequencies were not obviously modified by infecting the mice with a higher dose of virus.