Epidemiology and genetic variability of human metapneumovirus during a 4-year-long study in Southeastern Brazil.

Epidemiological and molecular characteristics of human metapneumovirus (hMPV) were compared with human respiratory syncytial virus (hRSV) in infants and young children admitted for acute lower respiratory tract infections in a prospective study during four consecutive years in subtropical Brazil. GeneScan polymerase chain assays (GeneScan RT-PCR) were used to detect hMPV and hRSV in nasopharyngeal aspirates of 1,670 children during January 2003 to December 2006. hMPV and hRSV were detected, respectively, in 191 (11.4%) and in 702 (42%) of the children admitted with acute lower respiratory tract infections at the Sao Paulo University Hospital. Sequencing data of the hMPV F gene revealed that two groups of the virus, each divided into two subgroups, co-circulated during three consecutive years. It was also shown that a clear dominance of genotype B1 occurred during the years 2004 and 2005, followed by genotype A2 during 2006.

Positive selection results in frequent reversible amino acid replacements in the G protein gene of human respiratory syncytial virus.

Human respiratory syncytial virus (HRSV) is the major cause of lower respiratory tract infections in children under 5 years of age and the elderly, causing annual disease outbreaks during the fall and winter. Multiple lineages of the HRSVA and HRSVB serotypes co-circulate within a single outbreak and display a strongly temporal pattern of genetic variation, with a replacement of dominant genotypes occurring during consecutive years. In the present study we utilized phylogenetic methods to detect and map sites subject to adaptive evolution in the G protein of HRSVA and HRSVB. A total of 29 and 23 amino acid sites were found to be putatively positively selected in HRSVA and HRSVB, respectively. Several of these sites defined genotypes and lineages within genotypes in both groups, and correlated well with epitopes previously described in group A. Remarkably, 18 of these positively selected tended to revert in time to a previous codon state, producing a "flip-flop" phylogenetic pattern. Such frequent evolutionary reversals in HRSV are indicative of a combination of frequent positive selection, reflecting the changing immune status of the human population, and a limited repertoire of functionally viable amino acids at specific amino acid sites.

Positive selection results in frequent reversible amino acid replacements in the G protein gene of human respiratory syncytial virus

Human respiratory syncytial virus (HRSV) is the major cause of lower respiratory tract infections in children under 5 years of age and the elderly, causing annual disease outbreaks during the fall and winter. Multiple lineages of the HRSVA and HRSVB serotypes co-circulate within a single outbreak and display a strongly temporal pattern of genetic variation, with a replacement of dominant genotypes occurring during consecutive years. In the present study we utilized phylogenetic methods to detect and map sites subject to adaptive evolution in the G protein of HRSVA and HRSVB. A total of 29 and 23 amino acid sites were found to be putatively positively selected in HRSVA and HRSVB, respectively. Several of these sites defined genotypes and lineages within genotypes in both groups, and correlated well with epitopes previously described in group A. Remarkably, 18 of these positively selected tended to revert in time to a previous codon state, producing a "flipflop" phylogenetic pattern. Such frequent evolutionary reversals in HRSV are indicative of a combination of frequent positive selection, reflecting the changing immune status of the human population, and a limited repertoire of functionally viable amino acids at specific amino acid sites.

Comparison of HeLa-I, HEp-2 and NCI-H292 cell lines for the isolation of human respiratory syncytial virus (HRSV).

Generally, laboratory diagnosis of viral respiratory infections utilizes virus isolation in cell culture and immunofluorescence assays. In this study, three cell lines (HEp-2, NCI-H292 and HeLa-I) were used for HRSV isolation of strains obtained from patients admitted at HU-USP with respiratory tract disease. HRSV was isolated in 46% (37) of 80 specimens inoculated in HeLa-I, 48% (39) in HEp-2, and 36.3% (29) in NCI-H292. Immunofluorescence was considered the gold standard and yielded 53% positive (43). The results from both methods combined had better sensitivity (73.2%) compared to either method alone. Comparing results between the cell lines with HEp-2 cells as the benchmark, the greatest sensitivity (72.2%) was observed in HeLa-I. This data shows that HeLa-I is adequate for HRSV isolation, giving results similar to the HEp-2 cells. The combined use of the HEp-2, HeLa-I and NCI-H292 cells improve the detection of HRSV.

Molecular epidemiology of human adenovirus isolated from children hospitalized with acute respiratory infection in São Paulo, Brazil.

In a study of acute respiratory disease, two collections of nasopharyngeal aspirates (NPA) were obtained from children hospitalized at the Pediatric Clinic of the University Hospital, São Paulo, in 1995 and 2000. Adenovirus was detected in 33 (8.2%) of 401 children followed. These viruses were isolated in HEp-2, HEK-293, or NCI-H292 cells and serotyped by neutralization. The genome types were determined after restriction analyses of the genomic DNA extracted from infected cells. Nineteen isolates were characterized as Human adenovirus B, genome types HAdV-3a, HAdV-7h, and HAdV-7h1; 11 as Human adenovirus C, genome types HAdV-1D10, HAdV-2D25, HAdV-5D2, and HAdV-6D3. Our findings show that species C adenoviruses present an endemic infection pattern, with co-circulation of different serotypes and genome types; no new genomic variant was observed. Species B adenoviruses showed epidemic infection patterns, with shifts in the predominant genome type. The isolates from 1995 belong to genome type 7h, or the variant 7h1, with a clear substitution of the type 7b, prevalent in São Paulo for more then 10 years. In 2000, the variant 7h1 predominated and the emergence of the type 3a was observed. Almost 10 years passed between the identification of HAdV-7h in Argentina and its detection in São Paulo. The geographic isolation of these two countries was reduced by the increase in population mobility due to growing commercial relationships.

Clinical patterns and seasonal trends in respiratory syncytial virus hospitalizations in Säo 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....

Infecçöes virais em crianças internadas por doença aguda no trato respiratório inferior / Viral infections in hospitalized children affected by acute lower respiratory tract disease

Objetivo: Avaliar a freqüência dos principais vírus respiratórios em crianças internadas por doença do trato respiratório inferior em hospital universitário. Métodos: Foi realizado estudo prospectivo que incluiu duas coortes de crianças internadas no período de abril a julho de 1996. Os grupos selecionados segundo a presença de patologia deo trato respiratório inferior: Grupo A - com doença aguda (tempo de história inferior a sete dias), e B-sem patologia respiratória presente ou recente. Os parâmetros para definiçäo de doença do trato respiratório inferior incluíram alteraçöes na propedêutica pulmonar e/ou às radiografias simples do tórax. Foram pré-definidos critérios clínicos e radiológicos para classificaçäo das doenças do trato respiratório inferior no grupo A. Foi coletado, à internaçäo, material da nasofaringe de todas as crianças para detecçäo de vírus, através de cultura em meio celular e por imunofluorescência direta. Resultados: Foram selecionados 201 casos, 126 no grupo A e 75 no grupo B. Foram identificados vírus em 71 crianças do grupo A (56,4 por cento), enquanto eram somente 3 no grupo B (4,0 por cento). Nas crianças do grupo A foi predominante o vírus respiratório sincicial, detectado em 66 casos, sendo também identificados adenovírus (4) e influenza (1) em outros pacientes. No grupo B foram identificados dois pacientes com vírus respiratório sincicial e um com adenovírus. Os pacientes do grupo A que apresentavam vírus respiratório sincicial tinham mediana de idade (3 meses) menor do que os outros casos deste grupo (13 meses) e apresentavam mais sibilância ao exame físico (78,7 por cento versus 33,3 por cento). Este vírus esteve associado à maior parte dos casos de broquiolite (84 por cento) e à metade das pneumonias (46,4 por cento). Conclusöes: Os autores constataram uma significativa presença de vírus na maior parte dos casos de crianças internadas com patologia aguda do trato respitatório inferior...

Eficácia da vacina Sabin em crianças subnutridas da amazônia / The efficacy of oral polio vaccine in malnourished Amazonial children

A eficácia da vacina Sabin foi determinada em 106 crianças normais e subnutridas da Amazônia, após a administraçäo de uma e duas doses de vacina oral (trivalente). Após a aplicaçäo de uma dose de vacina, verificou-se que apenas 9% das crianças com subnutriçäo pregressa (crônica) e 43% das crianças normais formaram anticorpos neutralizantes (protetores) contra dois ou três tipos de poliovírus (p=0,04). Após duas doses de vacina, os níveis de imunidade dos dois grupos de crianças estudadas acusaram, respectivamente, 32% e 75% (p=0,001). Estes resultados mostram que a resposta imunitária à vacina Sabin foi sensivelmente inferior no grupo das crianças subnutridas, do que no das crianças normais. Em decorrência disto, será necessário administrar um número maior de doses de vacina oral àquelas crianças, a fim de que níveis satisfatórios de imunidade contra a poliomielite sejam atingidos em toda a populaçäo infantil