Ultrastructural development and persistence of guinea pig cytomegalovirus in duct cells of guinea pig submaxillary gland

Abstract

Salivary glands from Hartley guinea pigs were experimentally infected with guinea pig cytomegalovirus (GPCMV) and examined by light and electron microscopy at different time intervals. Characteristic intranuclear and intracytoplasmic viral inclusions were observed in duct cells of infected animals. Viral inclusion counts and infectivity titers in the salivary gland reached maximum levels by 3 to 4 weeks after infection; infectivity persisted, though at reduced levels, for at least 30 weeks. Electron microscopic examination of viral inclusions revealed several developmental events including nucleocapsid assembly, envelopment of nucleocapsids at the inner nuclear membrane and their enclosure by a thin vacuolar membrane. While contained within cytoplasmic vacuoles, enveloped virions acquired surface spikes. Cytoplasmic vacuoles containing virions subsequently coalesced and discharged mature virions at the cell surface into the lumen of the salivary gland duct. The data indicate that the ultrastructural development of GPCMV in the guinea pig salivary gland shows many similarities to that of human cytomegalovirus in humans. The salivary gland may provide a primary locus for virus shedding and horizontal transmission of cytomegalovirus.

Ultrastructural Localization of Cytomegalovirus DNA Synthesis in Infected Guinea-pig Cells

“…in cross-section, are occasionally present in small bundles in GPCMV-infected GPE cells. These structures are also present in large quantities in the nuclei of GPCMV-infected guinea-pig salivary gland duct cells in vivo (Fong et al, 1980). Similar fibrils have been observed in cells infected with murine cytomegalovirus (Ruebner et al, 1966), human cytomegalovirus in vivo (Kawanishi et al, 1967), and herpes simplex virus-infected WI-38 cells in vitro (Luetzeter & Heine, 1978).…”

An Ultrastructural Investigation of Cytomegalovirus Replication in Murine Hepatocytes

“…As described by others, the first structural evidence of cytomegalovirus replication is seen in the nucleus (Ruebner et al, 1964(Ruebner et al, , 1965Middlekamp et al, 1967;Fong et al, 1979Fong et al, , 1980Fong, 1982). Fibrillo-granular electron-dense material, amorphous electron-dense matrices, the uncommon distinct fibrillar structures and obvious nucleocapsids all heralded replication of MCMV in infected murine hepatocytes.…”

“…Both, however, are probably only a stage in the formation of complete virions, but only the first has been previously reported (Ruebner et al, 1964(Ruebner et al, , 1965Middlekamp et al, 1967;Fong et al, 1979Fong et al, , 1980Fong, 1982).…”

Replication of herpes-like viruses in haemocytes of adult flat oysters Ostrea angasi:an ultrastructural study

“…Capsids and nucleocapsids occur along the edge of the coarse matrix (Kanich & Craighead 1972, Iwasaki et al 1973, Smith & d e Harven 1973, Fons & Albrecht 1986, the site of viral DNA production (Fong 1982, Wolber et al 1988. At this site in CMV infections, fibrils of viral DNA (Fong 1982) form fibrillar, vermiform, or tadpole-shaped structures that enter the capsids (Ruebner et al 1965, Kanich & Craighead 1972, Fong et al 1980, Cavallo et al 1981, whereas in HSV infections encapsidation does not occur in association with specific inclusions (Luetzeler & Heine 1978, Whealy et al 1991. The strands or rods of dark material in June samples, and reticulated coarse granular inclusions in March samples, of Ostrea angasi may therefore be involved in DNA synthesis prior to encapsidation.…”