FIG 6.

HSV zosteriform disease in the mouse flank infection model as a means to assess viral neuronal spread. Anesthetized, 6-week-old female adult C57BL/6 mice were scarified on the flank within a 2-mm² area using an 18-gauge needle and then topically infected with 1 × 10⁶ PFU/mouse of HSV-1pUS9KBDR or HSV-1pUS9KBDM. Mice were scored for HSV disease at the primary skin site (measure of primary infection) and the secondary skin site (measure of ganglionic neuronal spread) per the lesion scoring scheme given in Materials and Methods. (A) Mean skin lesion scores (± SEM) at selected times (n = 5 mice/time point) from days 1 to 28 p.i. for HSV-1pUS9KBDM and HSV-1pUS9KBDR. Similar primary skin lesion scores were observed. A significant decrease in secondary skin lesion score (*, P < 0.05 by Wilcoxon signed-rank test), which peaked at day 8 p.i., was observed for HSV-1pUS9KBDM compared to that of HSV-1pUS9KBDR. In each case HSV-1pUS9KBDR behaved the same as parental strain F (not shown). (B) Illustration of the progression of zosteriform disease at both primary and secondary skin sites in the mouse flank model using HSV-1pUS9KBDM and HSV-1pUS9KBDR. Similar disease progression was observed at the primary (P) site for both viruses with a peak decrease at the secondary (S) site at day 8 p.i. for HSV-1pUS9KBDM. (C) qPCR analysis of total DNA extracted from mouse DRG tissue (n = 5 mice/virus) at day 4 p.i. Levels of total viral genome copy number present in DRG tissue from infected mice were not significantly different between HSV-1pUS9KBDM and HSV-1pUS9KBDR. This confirms that there were no defects in the retrograde transport of HSV-1pUS9KBDM. The standard curve was based on a plasmid containing the HSV-1 UL35 gene. Samples were normalized to mGAPDH.