Putative new heat-stable cytotoxic and enterotoxic factors in culture supernatant of Escherichia coli isolated from drinking water

Enteric infections caused by the ingestion of contaminated water, especially by Escherichia coli, are important to define the virulence properties of these bacteria. Due to frequent infantile diarrhea in the city of Ouro Preto, Minas Gerais state, Brazil, the phenotypic and genotypic diarrheagenic properties of E. coli isolated from drinking water were studied. The culture supernatants of 39 (40 percent) among a total of 97 E. coli isolates from drinking water were positive by suckling mouse assay and induced cytotoxic effects on Vero cells. The enterotoxic and cytotoxic activities were present in the fraction with less than 10 kDa and were not lost when heated up to 60¨¬C and 100¨¬C for 30 minutes. PCR assays showed that among these 39 Vero cytotoxigenic E. coli, four (10.2 percent) were positive for ST II (estB) and two (5 percent) positive for ¥áHly (hlyA). Gene amplification of SLT (stx 1, stx 2), ST I (estA), LT (eltI, eltII), EAST1 (astA), EHly (enhly) and plasmid-encoded enterotoxin (pet) were not observed. This heat-stable cytotoxic enterotoxin of E. coli is probably a new putative diarrheagenic virulence factor, as a toxin presenting these characteristics has not yet been described.

Molecular basis for porcine parvovirus detection in dead fetuses

Reproductive failures are still common grounds for complaint by commercial swine producers. Porcine parvovirus (PPV) is associated with different clinical reproductive signs. The aim of the present study was to investigate PPV fetal infection at swine farms having ongoing reproductive performance problems. The presence of virus in fetal tissues was determined by nested-polymerase chain reaction assay directed to the conserved NS1 gene of PPV in aborted fetuses, mummies and stillborns. Fetuses show a high frequency of PPV infection (96.4%; n = 28). In 60.7% of the fetuses, PPV were detected in all tissue samples (lung, heart, thymus, kidney, and spleen). Viral infection differed among fetal tissues, with a higher frequency in the lung and heart (p < 0.05). Fetuses with up to 99 days of gestational age and from younger sows showed a higher frequency of PPV (p < 0.05). No significant difference in the presence of PPV was detected among the three clinical presentations. The results suggest that PPV remains an important pathogenic agent associated with porcine fetal death.

Teste de coaglutinaçäo para detecçäo de rotavirus / Coagglutination assay for detection of rotaviruses

Resumo: O teste de coaglutinaçäo foi utilizado para a detecçäo de rotavírus em fezes de origem humana e de suínos. Suspensäo de Staphylococcus aureos, produtor de proteina A, foi sensibilizada com uma diluiçäo seriada de antissoro anti-rotavirus do grupo A mostrando que quando foi utilizada a diluiçäo a 1:20, o teste foi capaz de detectar tanto antígeno SA11 como também o extrato fecal, ambos diluídos. Um total de 89 amostras de fezes absorvidas com S. aureus foram testadas por coaglutinaçäo e por um ensaio imunoenzimático. A análise estatística dos resultados obtidos mostrou uma concordância de 0,91 entre os dois testes o que levou-nos a conluir que a coaglutinaçäo é um método simples, rápido, sensível e pouco dispendioso para a detecçäo de rotavírus diretamente do material fecal. Além da utilizaçäo do soro diluído para a sensibilizaçäo de s> aureus ficou demonstrado também que, esta mistura, quando estocada a 4 graus C pode ser utilizada por até 6 meses após o seu preparo, sem implicar em resultados falso-positivos (au)

Comparison of indirect immunofluorescencee with agar gel immunodiffusion for the diagnosis of bluetongue virus infection

Sera from 190 cows and from 72 sheep were examined to compare the results obtained with the agar gel immundiffusion (AGIP) and indirect immunofluorescence (IIF) tests for the diagnosis of bluetongue (BT) disease. In the AGIP test, 96 of 190 (50.5%) cattle serum samples and 38 of 72 (52.7%) sheep serum samples were positive, for a total of 134 out of 262 (51.1%) sera. In the IIF test, 98 of 190 (51.6%) cattle serum samples and 39 of 72 (54.2%) sheep serum samples were positive, for a total of 137 out of 262 (52.3%) sera. The fluorescence of the IIF test presented a granular cytoplasmic aspect, which in some cells was observed only on the cell membranes. Statistical analysis of the data showed close agreement between the two techniques, regardless of the kind of sera examined. The IIF test showed high sensitivity (93.8% and 92.1%), specificity (91.4% and 88.2%) and positive (91.8% and 89.7%) and negative (93.48% and 90.9%) predictive values for cattle serum and sheep serum, respectively. The results obtained with obtained with IIF were comparable to those obtained with the AGIP test, indicating that both techniques can be used routinely in epidemiologic studies of BT. However, the IIF offers the additional advantages that it can be used for antibody quantification and for the detection of viral antigens in BT-infected cell lines