No abstract

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.

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.

SUMMARYIn May 1980 an extensive outbreak ofgastroenteritis 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 ofthe 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.

Particles morphologically identical to rotaviruses were found in the faeces of a nine week-old child with gastroenteritis. Analysis of the viral RNA genome by polyacrylamine gel electrophoresis revealed 10 bands (probably 11 segments) some of wich differed in migration rate from those of the great majority of rotaviruses infecting man and other animal hosts. The virus was not detected by a highly sensitive enzyme immunoassay (ELISA) and therefore probably lacked the crossreactive antigen(s) shared by the majority rotaviruses. This was the only strain with such behaviour among 230 rotaviruses of human origin examined in this laboratory since 1979. The implications of the existence of non-crossreactive rotaviruses are discussed.
Partículas morfologicamente idênticas a rotavirus foram encontradas nas fezes de uma criança de dois meses com gastroenterite. Análise do genoma viral por eletroforese em gel de poliacrilamida revelou 10 faixas (provavelmente 11 segmentos) de RNA, algumas das quais diferem em velocidade de migração das observadas na grande maioria de rotavirus de hospedeiros humanos e de diversas espécies de animais. O vírus não foi revelado por um ensaio imuno-enzimático de alta sensibilidade, o que sugere a ausência do antígeno de grupo que da reações cruzadas entre a maioria dos rotavirus. O vírus descrito no presente trabalho foi o único com tal comportamento entre 230 amostras analisadas por nós desde 1979. A relevância de existência de rotavirus não relacionados antigenicamente a outros membros do grupo é discutida