Figure 2

Increased percentage of splenic CD11b⁺Gr-1⁺cells during leukocytosis phase of HV-68 infection and during viral latency. Groups of Balb/c mice were mock-treated or intranasally infected with HV-68 virus. During the peak of viral-induced leukocytosis (15 days post-infection) or after viral latency had been established (30 days post-infection), bone marrow cells and splenocytes were isolated from individual animals and labeled with fluorchrome-conjugated anti-CD11b and anti-Gr-1 antibodies. FACS analysis was performed to determine the percentage of CD11b⁺ Gr-1⁺ cells in each cell population. Results are presented as mean values (N = 5) ± standard errors for bone marrow cells (Panel A) or spleen cells (Panel B).Asterisks indicate a statistically significant difference (p < 0.05) when comparing Mock versus HV-68 infected mice. These studies were performed three times with similar results. To demonstrate viral latency in mice infected for 30 days (Panel C), RNA isolated from spleens was subjected to RT-PCR to detect expression of the M3 RNA (a latent transcript) and the lack of expression of ORF 50 RNA (a replicating viral transcript). Representative results of one animal (N = 5) are presented as amplified products electrophoresed on ethidium bromide-stained gels. Positive controls (+) for ORF50 and M3 amplifications are shown in the last lane. Presence of GAPDH mRNA expression in each RNA sample using RT-PCR was also performed as a positive control.