Observations on recovery from and recurrence of HSV-2 infections in adult mice that were rescued from lethal vaginal infection by antiviral therapy

Use of transcriptional profiling to delineate the initial response of mice to intravaginal herpes simplex virus type 2 infection

Intravaginal (ivag) infection of mice with herpes simplex virus type 2 (HSV-2) causes genital tissue damage, quickly followed by development of fatal encephalopathy. To delineate initial host responses generated by HSV-2 infection, here oligonucleotide microarrays compared gene expression in vaginal tissue from uninfected mice and mice 1, 2, 3, 4, 5, 6, or 7 days after ivag infection with 10(4) pfu HSV-2. While comparison of mRNA expression in uninfected and HSV-infected vaginal tissue detected few changes during the first 2 days post infection (dpi), there were 156 genes whose expression was first significantly altered 3 dpi that remained significantly modified at all later time points examined. These 156 genes were significantly enriched in canonical pathways associated with interferon (IFN) signaling, activation of IFN elements by intracellular pattern recognition receptors, and antiviral immunity induced by cytosolic RIG-like receptors. Evaluation of this gene set with the National Center for Biotechnology Information Gene and INTERFEROME databases corroborated pathway analysis, as function of most (53%) were linked to IFN-mediated host immunity. In the final set of experiments, ivag administration of the Toll-like receptor 3 agonist polyinosinic: polycytidylic acid (poly I:C) 24 h before ivag HSV-2 infection reduced the incidence of genital pathology and encephalopathy, while these poly I:C-treated mice were subsequently protected from ocular HSV-2 challenge lethal to uninfected controls. The latter results imply that the exuberant antiviral immunity produced in our experimental model is simply formed too late to prevent viral replication and dissemination, and that poly I:C-induced formation of an antiviral state protecting against primary ivag infection also permits development of HSV-specific protective immunity.

Recurrent vaginal shedding of herpes simplex type 2 virus in the mouse and effects of antiviral therapy

A mouse model of recurrent herpes simplex type 2 (HSV-2) would improve our understanding of the immunobiology of recurrent disease and provide a useful model for evaluating antiviral treatments. We developed a model to evaluate recurrent vaginal HSV-2 shedding using high-dose acyclovir (ACV) therapy beginning at 3 days post infection (dpi). Treatment with 150mg/kg of ACV for 10 days increased survival to 80% following vaginal challenge with HSV-2 strain 186 and to 100% after challenge with strain MS. We then evaluated recurrent vaginal HSV-2 shedding in surviving mice. Although infectious virus was not detected in vaginal samples after 21dpi, viral DNA was detectable by PCR in 80% of mice (47/59) on at least 1 day, while no animal was positive for virus on every day. ACV therapy administered from day 21 to 31 significantly reduced recurrent virus shedding during this period from 7.3% (8/109 swabs) to 0.8% (1/126 swabs) (p=0.013). Lastly, ACV-rescued HSV-2-infected mice treated with cyclophosphamide at 35 and 38dpi rapidly succumbed, indicating that this model can be used to study immune control of the persistent infection. Thus, this model provides an inexpensive model for evaluating therapeutic strategies and immune control of persistent HSV.

HSV type 2 infection increases HIV DNA detection in vaginal tissue of mice expressing human CD4 and CCR5

The goal of this study was to develop an in vivo murine model that can be used to study the influence of HSV-2 on HIV infection. Mice expressing transgenes for human CD4, CCR5, and Cyclin T1 were infected intravaginally with HSV-2 and 3-7 days later infected with HIV. HIV DNA was detected by real-time PCR. The frequency of detection of HIV DNA was significantly higher (65%) in vaginal tissue of HSV-2-infected mice compared to mock-infected mice (35%) when HIV was given 3 days after HSV-2. HSV-2-infected mice also had significantly higher levels of HIV DNA in vaginal tissue. HIV DNA was not detected in vaginal tissue of mice lacking human CD4. Longer periods (5 or 7 days) between infection with HSV-2 and HIV did not increase the frequency of detection or the amount of HIV DNA detected. HIV DNA was also detected in lymph nodes from some of the mice that were infected intravaginally with HSV-2 and HIV. Flow cytometric and mRNA analysis of human CD4 in vaginal tissue suggested that HSV-2 infection increased the number of T cells expressing human CD4 in vaginal tissue. This study provides evidence that HIV infection of cells occurs in the vagina of mice expressing human CD4, CCR5, and Cyclin T1 and that HSV-2 infection increases HIV infection. These findings demonstrate that this model can be used to study the mechanisms responsible for increased susceptibility to HIV in HSV-2-infected persons and for testing preventative treatments.