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The presence of antibodies against rotavirus was investigated by enzyme immunosorbent assay (ELISA) in two distinct groups of children living in a shanty town in Rio de Janeiro. One hundred and thirty six plasma samples were randomly collected from children of 0 to 33 months (first group) and 255 serum samples were collected from other 85 children at ages of 2, 6 and 9 months (second group). A high percentage of antibodies were found in the newborn children and this rate decreased progressively until the age of 11 months, after which it increased again. At the age of 7 months, geometric mean antibody titers increased indicating that infection had occurred.

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Faeces from 746 children less than 5 years old with acute gastroenteritis were screened for the presence of adenovirus particles or antigens by immunoelectron microscopy (IEM) and enzyme immunoassay (EIA). Thirty-five samples were positive by both IEM and EIA, two only by IEM, and two only by EIA, giving a total of 39 (5.2%) samples with positive results. Of these, 25 could be propagated in HEp2 cells and were neutralized by one of the antisera to adenovirus types 1 to 18. The remaining 14 samples could be propagated only in the 293 permanent line of human cells transformed by adenovirus type 5 DNA [Graham et al, 1977] and were not neutralized by antisera to adenovirus types 1 to 31. An EIA carried out by the antibody-capture technique, using antiserum specific for "enteric" adenoviruses [Johansson et al, 1979], gave positive results with all isolates that could be propagated only in 293 cells and with none of those capable of growing in HEp2 cells.

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A combined enzyme immunoassay for rotavirus and adenovirus (EIARA) was developed as a double-antibody sandwich assay in which test samples are added to plastic wells coated with rotavirus or adenovirus goat antibody. The presence of antigens is detected by mixed-guinea pig antisera to the same viruses followed by rabbit anti-guinea pig IgG conjugated with peroxidase and subsequently by ortho-phenylenediamine substrate. Titrations of rotavirus (SA11) and adenovirus type 2 tissue culture grown viruses in the presence of separate capture sera and mixed detector sera revealed that the two virus-antibody reactions occurred independently and were not affected by each other. Comparison with another enzyme immunoassay for rotavirus, with immunoelectron microscopy and with polyacrylamide gel electrophoresis showed that EIARA is a sensitive and specific method for detecting rotaviruses and adenoviruses in faeces from children with gastroenteritis.

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A preparation of simian rotavirus SA11 was shown to contain, in addition to the normal 11 genome segments, an RNA species with electrophoretic mobility slightly higher than that of segment 4. Limiting dilution passages allowed the separation of two virus clones distinguishable from each other by the electrophoretic mobility of that genome segment. Possible implications of this finding in virus behaviour and in the comparison of rotaviruses by RNA electrophoresis are discussed.

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Detection of rotavirus RNA by polyacrylamide gel electrophoresis (PAGE) proved to be a highly sensitive and rapid diagnostic test. A comparison of this assay with immuno-electron microscopy (IEM) and enzyme immunoassay (EIA) in 245 faeces from children with gastroenteritis revealed complete agreement between the three assays in 238 (97.14%) samples. Among 75 samples positive in at least one of the three assays, negative results were observed in 5 (6.48%) by PAGE, in 6 (6.76%) by EIA and in none by IEM. Silver staining greatly increased the sensitivity of the PAGE assay. We conclude that although IEM remains the most sensitive and rapid rotavirus diagnostic assay, the PAGE technique has many advantages in its favour, including the non-requirement of expensive equipment, the use of only chemically defined reagents and the capacity to distinguish virus subgroup and variants and to detect non-crossreactive rotaviruses which are missed in serological assays.

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Human rotaviruses from the states of Rio de Janeiro, São Paulo and Pará of Brazil were analysed by RNA electrophoresis. At least some bands characteristic of rotavirus double-stranded RNA were detected in 138 (86.8%) of 159 faecal samples in which the presence of rotavirus had been demonstrated by enzyme immunoassay. Of the RNA-positive samples, 18 (13.0%) were classified as subgroup 1, 94 (68.1%) as subgroup 2, and 26 (18.8%) could not be classified due to absence of visible bands 10 and 11. Subgroup 2 was more frequent in the three states. All strains of subgroup 1 detected in Rio de Janeiro were associated with a single short-lived school outbreak. All strains of subgroup 1 resembled each other in electrophoretic pattern, irrespective of geographical origin, although minor differences could be detected by co-electrophoresis. Subgroup 2, on the other hand, showed a great degree of electrophoretic heterogeneity and could be divided into several sub-categories.

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Particulas morfologicamente identicas a rotavirus foram encontradas nas fezes de uma crianca de dois meses com gastroenterite. Analise do genoma viral por eletroforese em gel de poliacrilamida revelou 10 faixas (provavelmente 11 segmentos) de RNA, algumas das quais diferem em velocidade de migracao das observadas na grande maioria de rotavirus de hospedeiros humanos e de diversas especies de animais. O virus nao foi revelado por um ensaio imuno-enzimatico de alta sensibilidade, o que sugere a ausencia do antigeno de grupo que da reacoes cruzadas entre a maioria dos rotavirus. O virus descrito no presente trabalho foi o unico com tal comportamento entre 230 amostras analisadas por nos desde 1979. A relevancia de existencia de rotavirus nao relacionados antigenicamente a outros membros do grupo e discutida

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A evidenciacao da presenca de acido ribonucleico (ARN) viral por eletroforese em gel de policrilamida (EGPA) foi comprovada como um metodo altamente sensivel e rapido para o diagnostico de infeccoes por rotavirus. Uma comparacao desta prova com a imunomicroscopia eletronica (IEM) e com o ensaio imunoenzimatico (EIE) no exame de 245 fezes de criancas com gastroenterite revelou completa concordancia entre os tres ensaios em 238 (97.14%) amostras. Entre 75 amostras positivas pelo menos em um dos tres ensaios, resultados negativos foram observados em 5 (6.48%) por EGPA, em 6 (6.76%) por EIE e em nenhum por IEM. Coloracao pela prata aumentou consideravelmente a sensibilidade do ensaio por EGPA.Concluimos que embora a IEM ainda seja a prova mais sensivel e rapida para o diagnostico de infeccoes por rotavirus, o ensaio por EGPA tem muitas vantagens em seu favor, sendo as principais as de nao necessitar equipamentos caros, de empregar exclusivamente reagentes quimicamente definidos, de identificar grupos e variantes virais e de detectar amostras que nao possuindo antigenos comuns a maioria dos rotavirus, nao sao revelaveis por ensaios sorologicos

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In May 1980 an extensive outbreak of gastroenteritis occurred in a private school in the city of Rio de Janeiro. Examination of faeces and paired sera showed that this outbreak was caused by both rotavirus and a virulent strain of Shigella sonnei. In the first 19 stool samples collected seven (37%) had rotavirus only, six (32%) had Sh. sonnei only, while four (21%) had both agents. Examination of the second and third stool collections revealed only the presence of Sh. sonnei. The 18 paired sera showed seroconversion for rotavirus in four cases (22%) and in seven cases (39%) for Sh. sonnei. The overall attack rate of the disease was approximately 75%, the nursery and kindergarten having higher attack rates. Students in all grades became sick at the same time, and the unimodal curve of the onset dates of symptoms indicates a common source outbreak. Evidence suggested a contaminated water supply.

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