HSV-2 is a highly successful human pathogen with a remarkable ability to elude immune detection or counter the innate and adaptive immune response through the production of viral-encoded proteins. In response to infection, resident cells secrete soluble factors including chemokines that mobilize and guide leukocytes including T and NK cells, neutrophils, and monocytes to sites of infection. While there is built-in redundancy within the system, chemokines signal through specific membranebound receptors that act as antennae detailing a chemical pathway that will provide a means to locate and eliminate the viral insult. Within the central nervous system (CNS), the temporal and spatial expression of chemokines relative to leukocyte mobilization in response to HSV-2 infection has not been elucidated. This paper will review some of the chemokine/chemokine receptor candidates that appear critical to the host in viral resistance and clearance from the CNS and peripheral tissue using murine models of genital HSV-2 infection.
KeywordsGenital HSV-2; chemokines; chemokine receptors; leukocytes; CNS
HSV-2 BIOLOGYHSV-2 is a large (150-200nm) double-stranded, DNA virus and a member of the subfamily α-Herpesviridae [1,2]. A mature virus contains a core, an icosahedral capsid, a tegument in which additional viral proteins reside, and an outer envelope [1]. An approximately 150,000 base pair linear DNA is packaged inside the capsid that encodes at least 80 different viral genes [1]. The outer membrane envelope contains viral glycoproteins (e.g. gB, gC, gD and heterodimer gH/gL) involved in a multistep viral entry into the target cell [3,4]. The viral entry begins with interaction of gB and gC to heparin sulfate proteoglycans present on the surface of target cells followed by gD binding to other surface receptors including herpes virus entry mediator A and nectin-1α [2,4]. The viral envelope subsequently fuses with the target cell membrane which requires gD, gB and the heterodimer gH/gL [2]. Following viral entry, local replication commences with a sequential cascade of viral lytic gene transcription/translation and subsequent packaging of unit length viral DNA into empty viral capsids [5,6,7]. The capsid then acquires viral tegument and glycoproteins followed by the envelopment of the capsid on the underside of the nuclear membrane [6]. After successful packaging of infectious virions, the virus is released thru the rupture of the cell membrane where it will enter sensory nerve endings in the basal aspect of epithelium and via retrograde transport traffic to sacral ganglia in the CNS [7,8]. One of the hallmark features of HSV-2 is the establishment of latency in a subpopulation of neurons following acute infection of sensory ganglia [9,10]. In normal adults, it can cause recurrent infection at the original portal of entry as well as adjacent sites after reactivation [11].
HSV-2 INFECTION OF THE CNSHSV-2 is one of the most common causes of genital ulcer disease in humans that can result in fatal encephalitis and meningitis...