A block in glycoprotein processing correlates with small plaque morphology and virion targetting to cell-cell junctions for an oral and an anal strain of herpes simplex virus type-1

Abstract

The characteristics of two clinical isolates of HSV-1 obtained from an oral (424) and an anal (490) lesion were compared with the highly passaged KOS strain. In contrast to KOS, the clinical isolates produced small plaques, were more cell-associated and the predominant viral glycoprotein species for gC and gD in infected cell lysates was the precursor, high mannose glycoform. Total virus production in Vero cells was equivalent for the three virus strains in one-step growths. Pulse-chase studies of glycoprotein C processing showed a reduction in rate at 7.5 h post infection and a significant block in processing at 10.5 h post infection for 424 and 490 but not KOS. Similar results were obtained for gD. The significant reduction in glycoprotein processing for 424 and 490 suggests a block in transport of viral glycoproteins or virions to and through the Golgi apparatus. Extracellular virions and the cell surface, prior to cell lysis, contained the processed gC glycoform suggesting a competent cellular glycan processing system. Upon co-infection of 424 or 490 with KOS or a gC- KOS strain, gC was processed to levels equivalent to KOS indicating that 424 and 490 are not inhibitory but that an activity(s) encoded by KOS facilitates maturation of gC from 424 and 490. Unlike KOS infected Vero cells, virion-containing vacuoles were observed in the cytoplasm at 12 h p.i. and extracellular virions were concentrated at cell-cell junctions of 424 or 490 infected cells but not in the perinuclear region. These results suggest that intracellular transport of viral glycoproteins and virions in 424 and 490 infected cells is different from KOS infected cells. The reduced level of viral glycoprotein maturation, virus release, cell surface presence and presence of virions at cell-cell junctions are consistent with small plaque production in tissue culture cells.

Importance of NKT Cells in Resistance to Herpes Simplex Virus, Fate of Virus-Infected Neurons, and Level of Latency in Mice

“…This is relevant because a recent study in CD1d GKO mice concluded that NKT cells (type I and type II) are not critical for protection against the KOS strain of HSV-1 (8), contrasting with our own observations that disease was more severe in CD1d GKO mice infected with the neuropathic strain SC16 than in wt controls (15). Compared to the KOS strain (6,10,11,14,39), a neurovirulent clinical isolate such as SC16 can be expected to exercise the full range of host defenses, and we show here that important differences in the susceptibility of CD1d GKO mice, J␣18 GKO mice, and wt mice to SC16 are dependent on inoculation dose.…”

Strain-Dependent Structural Variants of Herpes Simplex Virus Type 1 ICP34.5 Determine Viral Plaque Size, Efficiency of Glycoprotein Processing, and Viral Release and Neuroinvasive Disease Potential

“…These studies were facilitated by the observation that the neuroinvasive isolates SP7 (7,21) and 490 (18) share a common tissue culture behavior, the small-plaque phenotype, which includes a restriction in viral glycoprotein processing and virion release, and an ICP34.5 protein with 18 PAT repeats in the center of the protein. In contrast, many attenuated viruses, such as KOS321, SLP5, and SLP10, produce large plaques and have only three PAT repeats (7,18). The ability of the pL/ST plasmid from KOS to genetically transfer the largeplaque phenotype into SP7 and 490 indicated that sequences containing ICP34.5 could eliminate the small-plaque phenotype (7; also data not shown), but the present studies demonstrate that specific isoforms of the ICP34.5 protein confer both the plaque phenotype and neuroinvasive disease potential onto the virus.…”

Intrastrain Variants of Herpes Simplex Virus Type 1 Isolated from a Neonate with Fatal Disseminated Infection Differ in the ICP34.5 Gene, Glycoprotein Processing, and Neuroinvasiveness

“…Previous studies from this laboratory identified a tissue culture phenotype which distinguished clinical isolates from the KOS laboratory strain (15). The clinical isolates produce small plaques on Vero cells and are cell associated, and viral glycoprotein processing appears to be restricted to the endoplasmic reticulum (small-plaque phenotype).…”