The cytopathic changes induced by poliovirus in cell cultures, first described by Robbins, Enders, and Weller (1), have since been observed by many workers. The description of the morphological changes however, has been limited to the late stages in the swollen and rounded cells, when the changes were so pronounced that they could be detected in the unstained preparations. In a preliminary investigation, it was noted that virus production occurred several hours before the cytopathic effect could be detected in living cultures. The possibility was then considered that a finer cytological study might show changes in the early stages of the cycle of virus multiplication in cultured cells. The present paper reports such a study, in which the sequence of intracellular changes occurring in monolayer cultures of monkey kidney cells after infection with poliovirus, has been related to the growth cycle of the virus. As the experiments were designed to determine the temporal relationship existing between the morphological changes in the infected cells and the appearance of newly formed virus within the cells and in the culture fluid, two conditions had to be fulfilled. Firstly, the cells in the culture should be infected within a brief period; ideally, simultaneous infection of all cells should occur. Secondly, a large proportion of the available cells should be infected with the original inoculum, to insure that the changes observed were actually induced by the seed virus. Materials and MethodsSince the synthesis of poliovirus in monkey kidney cells in tissue culture is rapid (complete within 8 hours), a variable lag in the response of the cells, due to a delay in virus adsorption or other factors, could result in a wide variation in the morphological character° istics of the ceils at a given time.
Urine specimens from 23 children and 9 adults who were undergoing treatment for malignancy as well as urines from 40 normal individuals were concentrated and examined for evidence of papovavirus infection. Papovavirus particles were detected in 6 of 64 urines examined by electron microscopy. Three of the particle-positive urines induced BK virus-specific immunofluorescence after inoculation of W138 cells, and three isolations of BK virus were made by inoculation of urines from virus-excreting patients into Vero cells. BK virusspecific hemagglutination-inhibiting and immunofluorescence neutralizing antibodies were found in a majority of urines from adult patients, in about a fifth of pediatric patients, and less often in normal urines. Urines of virus-excreting patients generally had antibodies. In indirect fluorescent antibody tests, BK virus-specific antibodies of the immunoglobulin G class were found in five urine specimens from patients; immunoglobulin A antibodies were not detected in any urine. These data suggest that activation of BK virus is related to immunosuppression and not to transplantation itself and that the occurrence of virus-specific antibodies in urine may be indicative of virus multiplication in the urinary tract.
SUMMARYA study has been made of the parenchyma of adult male Schistosoma mansoni by electron microscopy. Four different cell types have been characterized: one corresponding to cell bodies of the integument, two to muscle cells and another one to nerve cells with a possible neurosecretory function. The cytoplasm of the integument cell bodies is characterized by rod-shaped and round membrane-bound cytoplasmic bodies with a dense core, measuring 1200 to 2000 Å, similar to those found in the integument. One type of muscle cell has a large, clear nucleus, characteristic cytoplasmic vacuoles measuring up to 1 μm with a finely granular content and numerous free ribosomes. The other type of muscle cell is much smaller, with clumped nuclear chromatin and scanty perinuclear cytoplasm. Both types of cells give rise to muscle fibres which are morphologically distinct from the perinuclear cytoplasm. The nerve cells contain electron-dense, membrane-bound vesicles-ranging in size from 1000 to 3000 Å, similar to those found in nerve axons.Appreciable extracellular matrix has only been found under the integument and surrounding the processes of the integument cell bodies. This observation and the fact that silver methenamine after periodic oxidation stains intensely both the extracellular substance and the rod-shaped and round cytoplasmic bodies of the integument cells, suggests that these integument cells may be involve the production of extracellular matrix.This investigation was supported by grant AI 07806 from the U.S.P.H.S.The technical assistance of Mrs Lucille Jeffries and the photographic assistance of Mr William Douglas are acknowledged. This investigation was supported by the United States–Japan Cooperative Medical Science Program administered by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, Department of Health, Education and Welfare.
SA12 virus, originally isolated from an uninoculated South African vervet monkey kidney culture, was identified as a new member of the simian virus 40 (SV40)-polyoma subgroup of papovaviruses. The virus produced a cytopathic effect with nuclear enlargement in primary rhesus kidney cells. The virion had papovavirus morphology and a diameter of 44 to 45 nm. The DNA of the virus was a circular, double-stranded, superhelical molecule with a mean length 101% that of SV40 DNA and an estimated molecular weight of 3.3 X 10(6). The virus was found to be unrelated to other papovaviruses by neutralization, immune electron microscopy, and immunofluorescence tests with antiviral sera. SA12 virus-infected cells exhibited a capsid antigen, which has recently been found to be common to viruses of the SV40-polyoma subgroup. The virus readily transformed kideny cells from 10-day-old hamsters. Inoculation of transformed cells produced tumors in 3- to 4-week-old hamsters. The T antigens of SA12 and SV40 viruses were strongly and reciprocally cross-reactive. A high proportion of the sera of chacma baboons, Papio ursinus, and a comparatively lower proportion of the sera of vervet monkeys, Cercopithecus pygerythrus, had neutralizing antibodies to SA12 virus
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