Rotaviruses are the major cause of viral diarrhea in humans and animals. Actinomycin D (Act D) is an antibiotic that intercalates DNA and therefore inhibits DNA-dependent transcription. The current study was carried out to assess the influence of Act D on the replication of simian rotavirus (SA11) in cell culture. Virus-infected MA-104 cell cultures were studied in the presence of Act D at concentrations of 1.25 and 2.5 µg/ml. Treatment of rotavirus-infected cells with 2.5 µg/ml Act D 48 h post-infection reduced the cytoplasmic metachromasia after staining with acridine orange by 25%. Viral RNA labeled with ³H-uridine in the presence of the drug was separated by polyacrylamide gel electrophoresis. Viral RNA replication was not affected by Act D, but increased ³H-uridine uptake was demonstrable by infected cells in the presence of the drug. This possibly was due to the inhibition of cellular RNA synthesis by Act D, which thus enhances incorporation of the radionuclide into the viral RNA. Act D reduced the number of infected cells presenting virus-specific fluorescence 48 h post-infection by more than 50%. These data suggest that Act D may have complexed with viral RNA and prevented newly synthesized mRNA from being translated, but may not have prevented early replication.

A citopatologia in vitro de uma cepa de rotavírus porcino adaptado em cultura de células foi comparada à estirpe-protótipo símia (SA-11). O efeito citopático (ECP) produzido pelos vírus foi semelhante embora a estirpe porcina tivesse apresentado algumas alterações diferentes, como o acentuado estreitamento do citoplasma, com grande perda do volume citoplasmático. O vírus porcino apresentou menor número de plaques de ECP porém com diâmetro maior em relação ao vírus símio, demonstrando maior capacidade de disseminação célula-célula, quase oito vezes mais, a julgar pelo diâmetro dos plaques de ECP. Os elementos do citoesqueleto das células infectadas revelaram uma reorganização semelhante para ambas as estirpes, não sendo possível observar nenhuma diferença, embora o ECP do vírus porcino tenha sido mais acentuado.

Rotaviruses and reoviruses are involved in human and animal diseases. It is known that both viruses penetrate the gastrointestinal tract but their interaction with phagocytic cells is unknown. To study this interaction, peritoneal resident phagocytic cells were used and rotavirus and reovirus replication in peritoneal phagocytic cells was observed. However, rotavirus replication in these cells led to the production of defective particles since MA-104 cells inoculated with rotavirus phagocytic cell lysate did not show any evidence of virus replication. On the basis of these results, we suggest that, although reovirus dissemination may be helped by these phagocytic cells, these cells may control rotavirus infection and probably contribute to the prevention of its dissemination.

Realizamos este estudo para avaliar a relação causai diarréia aguda e rotavirus em crianças abaixo de cinco anos de idade. A infecção viral foi caracterizada pela sorologia pareada, por meio de titulação de anticorpos anti-rotavírus pela reação de imunofluorescência indireta (IF) nos soros dos pacientes. Utilizamos como substrato para a reação células MA-104 infectadas com o rotavirus bovino cepa UK. De 80 amostras de soros pareados, verificamos que 23 amostras (28,75%) apresentaram soroconversão, 19 amostras (23,75%) tiveram elevação no título de 2 vezes e em 38 amostras (47,5%) não observamos elevação no título de anticorpos anti-rotavírus. Estes resultados são confrontados com os resultados previamente obtidos na detecção do antígeno de rotavírus nas fezes, dos mesmos pacientes, pela técnica de contraimunoeletroforese (CIEOP).

A serological study was carried out to evaluate the causal relationship of acute diarrhoea and rotavirus in children under five years of age. The rotaviral infection was demonstrated in paired sera by determining the antibody titers by immunofluorescence test (IF). Bovine rotavirus-infected MA-104 cell culture was used as substratum for IF. Out of 80 paired sera it was shown that 23 (28.75%) presented seroconversion, 19 (23.75%) samples showed a twofold increase in their titers and 38 (47.5%) had no increase in rotavirus antibody. This result is discussed on the light of previously obtained results on viral antigen detection by counterimmunoelectrosmophoresis (CIEOP).