Immune response to respiratory syncytial virus in young Brazilian children.

We have evaluated the cellular and humoral immune response to primary respiratory syncytial virus (RSV) infection in young infants. Serum specimens from 65 patients <=12 months of age (39 males and 26 females, 28 cases <3 months and 37 cases > or = 3 months; median 3 3.9 months) were tested for anti-RSV IgG and IgG subclass antibodies by EIA. Flow cytometry was used to characterize cell surface markers expressed on peripheral blood mononuclear cells (PBMC) from 29 RSV-infected children. There was a low rate of seroconversion in children <3 months of age, whose acute-phase PBMC were mostly T lymphocytes (63.0 +/- 9.0%). In contrast, a higher rate of seroconversion was observed in children >3 months of age, with predominance of B lymphocytes (71.0 +/- 17.7%). Stimulation of PBMC with RSV (2 x 10(5) TCID50) for 48 h did not induce a detectable increase in intracellular cytokines and only a few showed a detectable increase in RSV-specific secreted cytokines. These data suggest that age is an important factor affecting the infants' ability to develop an immune response to RSV.

Immune response to respiratory syncytial virus in young Brazilian children

We have evaluated the cellular and humoral immune response to primary respiratory syncytial virus (RSV) infection in young infants. Serum specimens from 65 patients <=12 months of age (39 males and 26 females, 28 cases <3 months and 37 cases > or = 3 months; median 3 ± 3.9 months) were tested for anti-RSV IgG and IgG subclass antibodies by EIA. Flow cytometry was used to characterize cell surface markers expressed on peripheral blood mononuclear cells (PBMC) from 29 RSV-infected children. There was a low rate of seroconversion in children <3 months of age, whose acute-phase PBMC were mostly T lymphocytes (63.0 ± 9.0 percent). In contrast, a higher rate of seroconversion was observed in children >3 months of age, with predominance of B lymphocytes (71.0 ± 17.7 percent). Stimulation of PBMC with RSV (2 x 10(5) TCID50) for 48 h did not induce a detectable increase in intracellular cytokines and only a few showed a detectable increase in RSV-specific secreted cytokines. These data suggest that age is an important factor affecting the infants' ability to develop an immune response to RSV

Clinical patterns and seasonal trends in respiratory syncytial virus hospitalizations in São Paulo, Brazil.

The respiratory viruses are recognized as the most frequent lower respiratory tract pathogens for infants and young children in developed countries but less is known for developing populations. The authors conducted a prospective study to evaluate the occurrence, clinical patterns, and seasonal trends of viral infections among hospitalized children with lower respiratory tract disease (Group A). The presence of respiratory viruses in children's nasopharyngeal was assessed at admission in a pediatric ward. Cell cultures and immunofluorescence assays were used for viral identification. Complementary tests included blood and pleural cultures conducted for bacterial investigation. Clinical data and radiological exams were recorded at admission and throughout the hospitalization period. To better evaluate the results, a non- respiratory group of patients (Group B) was also constituted for comparison. Starting in February 1995, during a period of 18 months, 414 children were included- 239 in Group A and 175 in Group B. In Group A, 111 children (46.4%) had 114 viruses detected while only 5 children (2.9%) presented viruses in Group B. Respiratory Syncytial Virus was detected in 100 children from Group A (41.8%), Adenovirus in 11 (4.6%), Influenza A virus in 2 (0.8%), and Parainfluenza virus in one child (0.4%). In Group A, aerobic bacteria were found in 14 cases (5.8%). Respiratory Syncytial Virus was associated to other viruses and/or bacteria in six cases. There were two seasonal trends for Respiratory Syncytial Virus cases, which peaked in May and June. All children affected by the virus were younger than 3 years of age, mostly less than one year old. Episodic diffuse bronchial commitment and/or focal alveolar condensation were the clinical patterns more often associated to Respiratory Syncytial Virus cases. All children from Group A survived. In conclusion, it was observed that Respiratory Syncytial Virus was the most frequent pathogen found in hospitalized children admitted for severe respiratory diseases. Affected children were predominantly infants and boys presenting bronchiolitis and focal pneumonias. Similarly to what occurs in other subtropical regions, the virus outbreaks peak in the fall and their occurrence extends to the winter, which parallels an increase in hospital admissions due to respiratory diseases.

Genetic characterization of adenovirus strains isolated from patients with acute conjunctivitis in the city of São Paulo, Brazil.

Genome analysis was carried out on adenovirus strains isolated from patients with acute follicular conjunctivitis in the city of São Paulo, Brazil. Eighteen conjunctival scrapings, collected between December 1993 and March 1994, were analyzed by two methods: a combination of polymerase chain reaction with restriction fragment length polymorphism and viral DNA restriction analysis, carried out using 10 restriction endonucleases: BamHI, BglI, BglII, HindIII, KpnI, SacI, SalI, SmaI, XbaI, and XhoI. Among 11 adenovirus detected by cell culture isolation, nine were Ad8, and two were Ad7. By restriction analysis the Ad8 isolates were typed as two new variants-Ad8/D11 (seven of nine samples) and Ad8/D12 (two of nine samples). Ad7 isolates were identified as a subtype of the widespread genome type Ad7b and the virulent type Ad7h, a predominant genome type circulating in Argentina, Chile, and Uruguay but absent in Brazil until 1991.

[Viral infections in hospitalized children affected by acute lower respiratory tract disease] / Infecções virais em crianças internadas por doença aguda do trato respiratório inferior.

OBJECTIVE: To evaluate the frequency of the main respiratory viruses in hospitalized children affected by acute lower respiratory tract disease at a university hospital. METHODS: This is a prospective trial that included two cohorts of hospitalized children in the period from April to July 1996. The groups were selected according to the presence of lower respiratory tract disease on admission: Group A- with acute disease (history of less than 7 days) and B- without present or recent respiratory disease. The parameters for defining lower respiratory tract disease included physical and/or radiological pulmonary changes. Clinical and radiological criteria were established for the classification of lower respiratory tract diseases in group A. Nasopharyngeal swab was collected from all children on admission for viral detection by cellular cultures and direct immunofluorescence. RESULTS: 201 cases were selected, 126 in group A and 75 in group B. Viruses were identified in 71 children from groupA(56.4%) and only in 3 from group B (4.0%). The predominant agent in group A was respiratory syncytial virus, identified in 66 cases; adenovirus (4) and influenza (1) were detected in other patients. In group B two patients with respiratory syncytial virus and one with adenovirus were identified. The patients from group A affected by respiratory syncytial virus were younger (median age 3 months versus 13 months) and more wheezy on physical examination (78.7%) than the other patients of the group (33.3%). This virus was associated to most of the bronchiolitis cases (84%) and to half of the pneumonia cases (46.4%). CONCLUSION: The authors found a significant presence of viruses in the majority of children hospitalized with acute lower respiratory tract disease. The respiratory syncytial virus was the predominant agent identified. These results are similar to others previously reported both in developed and some developing countries. The authors emphasize that the present study evaluated only partially the possibility of simultaneous infection by other pathogens and that the present protocol was conducted during the season with the highest incidence of respiratory syncytial virus.

Detection of rotavirus in sewage and creek water: efficiency of the concentration method

Simian rotavirus SA-11, experimentally seede, was recovered from raw domestic sewage by a two-step concentration procedure, using filtration through a positively charged microporous filter (Zeta Plus 60 S) followed by ultracentrifugation, effecting an 8000-fold concentration. By this method, a mean recovery of 81 per centñ7.5 of the SA-11 virus was achieved.

Detection of rotavirus in sewage and creek water: efficiency of the concentration method.

Simian rotavirus SA-11 experimentally seeded, was recovered from raw domestic sewage by a two-step concentration procedure, using filtration through a positively charged microporous filter (Zeta Plus 60 S) followed by ultracentrifugation, effecting an 8,000-fold concentration. By this method, a mean recovery of 81% +/- 7.5 of the SA-11 virus, was achieved.

Humoral immunity patterns based on antibody reactivity to rotavirus antigens in Brazilian children under 5 years of age.

The age distribution of antibody to simian rotavirus (SA-11) was studied in serum specimens obtained from 399 children aged to 5 years and living in the city of Recife (PE), located in the north eastern region of Brazil. Sera were examined for group-specific rotavirus antibody using a blocking enzyme immunoassay (bELISA) and a hemagglutination inhibition antibody (HIA) test, and for anti-VP2, anti-VP4, anti-VP6, and anti-VP7 antibodies using an immunoblotting assay (IBA). Antibody prevalence was similar in all bELISA and HIA assays, showing a steep rise in the 6-to 17-month-old age groups. The results indicate early acquisition of antibody to rotavirus. The majority of children aged 2 to 4 years had bELISA (50% to 60%) and HIA (70% to 81%) antibodies. There was an association in prevalence data obtained by HIA and bELISA with immunoblotting (IBA), revealing four serologic profiles. Children with profiles I and II (60%) respectively had HAI and ELISA antibody or HAI antibody alone and all had immunoprotective antibodies to VP4 and/or VP7. These children were regarded as "immune," resembling convalescent patients with a rotavirus infection. Children with profile III (4%) had no HIA antibody and only non-protective anti-VP6 and/or VP7 antibody, and were considered to be "partially immune." Children with profile IV (36%) had no detectable antibody and were classified as "nonimmune." These children should be considered to be susceptible to rotavirus infection, with the risk of developing clinically severe diarrhea.

A combined staphylococcal coagglutination assay for rapid identification of rotavirus and adenovirus (COARA).

An improved staphylococcal coagglutination test was developed for rapid detection, in a single assay, of rotavirus and adenovirus in stool samples (COARA). Suspensions of Staphylococcus aureus coated respectively with anti-rotavirus and anti-adenovirus sera were used to identify these viruses in 327 stool samples of children. The samples were also tested by an enzyme immunoassay. The data analysis has demonstrated a high degree of correlation between the two assays.

Adenovirus genome types isolated from stools of children with gastroenteritis in São Paulo, Brazil.

In a prospective one-year study of acute gastroenteritis in hospitalized children less than 2 years of age, in São Paulo (Brazil), adenoviruses were detected by specific enzyme immunoassay (El-ARA) in 7 of 67 (10%) ill children and in 9 of 79 (11.4%) controls. They were the sole recognizable agent of diarrhea in 6 ill children. In another child these viruses were detected in a dual infection with astrovirus. Enteric adenoviruses (Ad40/41) were the most common serotypes detected in children with diarrhea (3/7) and Ad7 the serotype most detected in the controls (5/9), associated with lower respiratory tract infection. Thirteen adenovirus strains, isolated in HEp2 or HEK-293 cells, were characterized by seroneutralization and restriction enzyme analysis. The established adenoviruses were typed as AV-7-D5 (five associated to lower respiratory tract infection and one to diarrhea), AV-1-D10 (one diarrhea case), AV-31-D2 (two controls with respiratory infection), and two isolates as AV-12-D7, a new genome type. One subgenus D isolate, serotype 28, with restriction patterns different from those of the prototype, remained untyped. Only one enteric adenovirus could be typed. The restriction patterns of this isolated were similar to those of the prototype AV-41-D1. The genome type of the other three enteric adenoviruses could not be determined.

Serotypes and electropherotypes of human rotavirus detected in the city of São Luís (MA), Brazil.

A total of 22 (65%) of 34 representative rotavirus-positive specimens from infants with acute gastroenteritis were electropherotyped (RNA genome segments) and serotyped using an enzyme immunoassay with monoclonal antibodies (ELISA with MAbs). Serotype 3 was predominant during the 10-month study period (41%), followed by serotype 1 (27%) and serotype 4 (9%). Serotype 2 was not found. Rotavirus strains were grouped into 3 major electropherotypes designated V, W and Z, each corresponding to a single serotype, i.e., serotypes 1, 3 and 4, respectively. Three strains that could not be typed by the serologic technique showed the W electrophoretic profile. The relative migration of the gene segments 7-9 was the main feature distinguishing the predominant serotype 3 from the other serotypes. The migration of segments 2 and 5 was also important for differentiating serotype 4 strains. The present study strengthens the view that electropherotyping, when used in conjunction with serotyping, can help characterize atypical and unusual strains, as well as rotaviruses that cannot be typed by the serologic technique.

Serotypes and electropherotypes of human rotavirus detected in the city of São Luís (MA), Brazil

A total of 22 (65) of 34 representative rotavirus-positive specimens from infants with acute gastroenteritis were electropherotyped (RNA genome segments) and serotyped using an enzyme immunoassay with monoclonal antibodies (ELISA with MAbs). Serotype 3 was predominant during the 10-month study period (41), followed by serotype 1 (27) and serotype 4 (9). Serotype 2 was not found. Rotavirus strains were grouped into 3 major electropherotypes designated V, W and Z, each corresponding to a single serotype, i.e., serotypes 1, 3 and 4, respectively. Three strains that could not be typed by the serologic technique showed the W electrophoretic profile. The relative migration of the gene segments 7-9 was the main feature distinguishing the predominant serotype 3 from the other serotypes. The migration of segments 2 and 5 was also important for differentiating serotype 4 strains. The present study strengthens the view that electropherotyping, when used in conjunction with serotyping, can help characterize atypical and unusual strains, as well as rotaviruses that cannot be typed by the serologic technique.

Viral, bacterial and parasitic pathogens associated with severe diarrhoea in the city of São Paulo, Brazil.

Viral, bacterial and parasitic pathogens associated with diarrhoea were studied in infants and young children admitted to the paediatric clinic of the University Hospital of São Paulo during the period of 13 months. A recognised pathogenic organism was detected in 78% of the diarrhoeic patients, 6% of whom had a mixed infection with two agents. Enteropathogenic E. coli (EPEC) was the most common enteropathogen detected (22%), followed by rotavirus (19%) and adenovirus (10%). Altogether 6% had diarrhoea associated with Salmonella or Shigella and 3% showed diarrhoeal illness associated with astrovirus. Infants less than 6 months of age were most commonly infected with enterobacteria (35%), mainly enteropathogenic E. coli (30%), whereas children 6 months to 2 years presented more often with viruses (38%), mainly rotaviruses (25%). Enteropathogens were found during all seasons of the year and rotaviruses showed a seasonal variation.

Detection and distribution of rotavirus in raw sewage and creeks in São Paulo, Brazil.

Rotaviruses were concentrated from 8-liter samples of raw domestic sewage and sewage-polluted creek water by adsorption to and elution from positively charged microporous filters (Zeta Plus 60S), followed by ultracentrifugation of the filter eluates. Indirect immunofluorescence and direct immunoperoxidase methods allowed detection and enumeration of rotavirus in 6 (20.6%) of 29 sewage samples and in 19 (34.5%) of 55 creek water samples. Levels of rotaviruses ranged from < 3 to 63 focus-forming units (FFU)/liter, and the geometric means were 2.2 FFU/liter in sewage, 2.9 FFU/liter at creek Tremembé, and 2.6 FFU/liter at creek Pirajussara. Wastewater samples examined during autumn and winter months showed a higher rate positivity for rotavirus than those collected in spring and summer, corresponding to the seasonal variation of rotaviral diarrhea in the city of São Paulo.

Rotavirus associated diarrhoea during infancy in the city of S. Luís (MA), Brazil: a two-year longitudinal study.

A total of 479 diarrhoeic children and 337 children without diarrhoea (controls) less than 5 years old were investigated in a two-year study in the city of S. Luís (MA), with the purpose to determine the incidence, the age distribution and the seasonality of rotaviruses, as well as to establish the severity of the disease in this region between the North and the Northeast of Brazil. rotavirus incidence was highest in children of the 1st. year of life, showing an average of 25% per year among the diarrhoeic patients attending the two main hospitals and three health units at the periphery of the city. It was shown that rotaviruses are significant enteropathogens in children less than 18 months old. Frequency of rotaviruses dropped in diarrhoeic patients 18 to 23 months old to only 4%, the same percentage observed in children of the control group. A typical seasonal distribution of rotaviruses was not seen during the two years of study. There was a peak in the incidence of rotaviruses in 1986, during the rainy season, and two peaks in 1987, one in the rainy season and one in the dry season. It was also shown that severity of diarrhoea in rotavirus positive cases was higher than in the negative cases. Rotavirus diarrhoeic patients had more loose stools per day, and higher frequencies of vomiting and fever, resulting more often (> 2 times) in moderate or severe dehydration. Finally, it is concluded that the introduction of immunoprophylaxis may reduce significantly the high mortality rates in early childhood observed in S. Luís.

[Occurrence of human astrovirus in São Paulo City, Brazil]. / Ocorrência de astrovírus humanos na cidade de São Paulo, Brasil.

Human astrovirus was detected during a 13-month longitudinal study of the incidence of diarrhoea viruses among hospitalized children (less than 2 years of age) in a pediatric clinic of the city of S. Paulo (University Hospital). Serial fecal samples (intervals of 4 days) were collected from 146 children with and without acute diarrhoea at admission and during their stay in the hospital. Two (3%) of the 67 children with diarrhoea were positive at admission to the clinic by the highly sensitive ASTROVIRUS BIOTIN-AVIDIN ELISA, using CDC monoclonal antibodies (MAb SE7). All 79 children without diarrhoea (controls) were negative for astrovirus at admission. However, astrovirus was detected in 7 (4.8%) of the 146 hospitalized children during their stay in the clinic. Three of the positives shed astroviruses in 2 successive stool samples. All children positive for astrovirus were negative for rotavirus, adenovirus and bacterial and parasitic enteric agents. This is the first study of the detection of human astrovirus in Brazil. Astrovirus appears to be a significant cause of infantile gastroenteritis among young children in this country.

Sindrome "mononucleose simile" na infancia. Incidencia da infeccao por citomegalovirus diagnosticada atraves de deteccao imunoenzimatica de anticorpos IgM. / Mononucleosis-like syndrome in childhood. Incidence of cytomegalovirus infection diagnosed by immunoenzymatic detection o IgM antibodies

Testando anticorpos IgM anti-citomegalovirus, pela tecnica imunoenzimatica ELISA, em 82 criancas com doenca "mononucleose simile" (reacao de Paul-Bunnell-Davidsohn negativa), os Autores diagnosticaram 5 casos (6%) de infeccao aguda por este agente. A presenca de linfonodomegalia cervical e exsudato de amigdalas em alguns destes pacientes sugere que a apresentacao clinica da citomegalomononucleose na infancia poderia, por vezes, ser distinta da forma classica do adulto