Growth characteristics and immunocytochemical studies of reovirus type 2 in a line of human amnion cells

Biological and physico-chemical properties of the infectious bursal disease virus (IBDV)

Some biological properties of an egg-adapted strain of IBDV, PV1, have been studied. By immunofluorescent staining the strain is serologically identical to another egg-adapted strain, MU2, and to three pathogenic strains of IBDV. All five strains do not react with antisera prepared against known avian viruses of various groups, including Reoviruses. The egg-adapted strain PV1 replicates in chick embryo fibro-blasts and in RK13 cells, with the formation of plaques. The PV1 strain, highly neuropathogenic for newborn mice, is not neuropathogenic for newborn chicks. Various physico-chemical characteristics of IBDV have been studied in comparison to Crawley Reovirus, namely resistance to 5-iodo-2-deoxyuridine, heat-resistance, stability over a wide pH range, resistance to photodynamic inactivation and UV irradiation, sensitivity to Actinomycin D. As Reoviruses, IBDV is a naked RNA Virus, sensitive to Actinomycin D. It is more resistant than Reoviruses to heat, UV irradiation and photodynamic in-activation. All these findings are discussed in relationship to the taxonomic position of IBDV. Cytological observations are reported on cells infected with IBDV and the growth curve is described.

Size and structure of the genome of infectious pancreatic necrosis virus

The genome of infectious pancreatic necrosis virus consists of two segments of dsRNA, in equimolar amounts, with molecular weights of 2.5 X 10(6) and 2.3 X 10(6) daltons, as determined by polyacrylamide gel electrophoresis and autoradiography. The viral RNA was resistant to ribonuclease, and in sucrose gradient it co-sedimented at 14S with RNase resistant RNA from virus infected cells. Upon denaturation in 98% formamide, the viral genome sedi-mented at 24S in formamide sucrose gradient and became sensitive to RNase. Denatured 24S viral RNA did revert to its undenatured 14S form upon recentrifugation in aquaeous sucrose gradient (0.1 M NaCL), but co-sedimented with the denatured large size class of reovirus 25S RNA. The same results were obtained if the native viral RNA was pre-treated with ribonuclease before denaturation, indicating the absence of exposed single strainded regions in the viral genome. Since infectious pancreatic necrosis virus contains only two dsRNA segments it does not belong to the family Reoviridae and may represent a new group of viruses.

Production in FL cells of infectious and potentially infectious reovirus

Spendlove, Rex S. (California State Department of Public Health, Berkeley), Edwin H. Lennette, Charles O. Knight, and Jean N. Chin. Production in FL cells of infectious and potentially infectious reovirus. J. Bacteriol. 92:1036-1040. 1966.-A comparative study was made of the development in, and release from, FL cells of infectious and potentially infectious (chymotrypsin-activatable) reovirus (Lang strain). The latent period was shorter, the rate of synthesis was more rapid, and the total yield was more than 10-fold greater in potentially infectious virus as compared with infectious virus. Almost all of the potentially infectious virus, but only approximately one-third of the infectious virus, was released from the infected cells.