First report of human astrovirus MLB2 in Brazil detected in feces of children with acute gastroenteritis living in the state of Roraima, Northern Brazil

ABSTRACT Human astrovirus (HAstV) 1-8 and highly divergent HAstVMLB1−3 genotypes have been detected in children both with and without acute gastroenteritis (AGE). One hundred and seventy fecal samples from children (≤5 years old) living in the Amazon region were evaluated for the presence of HAstV1-8, HAstV MLB1−3 and HAstVVA1−3, using an usual RT-PCR protocol and a new protocol with specific primers designed to detect HAstVMLB1−3. HAstVMLB1 and HAstV MLB2, as well as the HAstV3 and 5 genotypes were detected. HAstVMLB1−2 genotype was detected for the first time in Brazil at a frequency of 3.5% (6/170).

Detection and genetic characterization of Mamastrovirus 5 from Brazilian dogs

Abstract Mamastrovirus 5 (MAstV5), belonging to the Astroviridae (AstV) family, previously known as canine astrovirus or astrovirus-like particles, has been reported in several countries to be associated with viral enteric disease in dogs since the 1980s. Astroviruses have been detected in fecal samples from a wide variety of mammals and birds that are associated with gastroenteritis and extra enteric manifestations. In the present study, RT-PCR was used to investigate the presence of MAstV5 in 269 dog fecal samples. MAstV5 was detected in 26% (71/269) of the samples. Interestingly, all MAstV5-positive samples derived from dogs displaying clinical signs suggestive of gastroenteritis, other enteric viruses were simultaneously detected (canine parvovirus, canine distemper virus, canine coronavirus, canine adenovirus and canine rotavirus). Based on genomic sequence analysis of MAstV5 a novel classification of the species into four genotypes, MAstV5a-MAstV5d, is proposed. Phylogenetic analyses based on the ORF2 amino acid sequences, samples described herein grouped into the putative genotype 'a' closed related with Chinese samples. Other studies are required to attempt the clinical and antigenic implications of these astrovirus genotypes in dogs.

Acute gastroenteritis and enteric viruses in hospitalised children in southern Brazil: aetiology, seasonality and clinical outcomes

Viral acute gastroenteritis (AG) is a significant cause of hospitalisation in children younger than five years. Group A rotavirus (RVA) is responsible for 30% of these cases. Following the introduction of RVA immunisation in Brazil in 2006, a decreased circulation of this virus has been observed. However, AG remains an important cause of hospitalisation of paediatric patients and only limited data are available regarding the role of other enteric viruses in these cases. We conducted a prospective study of paediatric patients hospitalised for AG. Stool samples were collected to investigate human adenovirus (HAdV), RVA, norovirus (NoV) and astrovirus (AstV). NoV typing was performed by nucleotide sequencing and phylogenetic analysis. From the 225 samples tested, 60 (26%) were positive for at least one viral agent. HAdV, NoV, RVA and AstV were detected in 16%, 8%, 6% and 0% of the samples, respectively. Mixed infections were found in nine patients: HAdV/RVA (5), HAdV/NoV (3) and HAdV/NoV/RVA (1). The frequency of fever and lymphocytosis was significantly higher in virus-infected patients. Phylogenetic analysis of NoV indicated that all of these viruses belonged to genotype GII.4. The significant frequency of these pathogens in patients with AG highlights the need to routinely implement laboratory investigations.

Prevalence of Human Astrovirus in Patients with Acute Gastroenteritis

The prevalence of human astroviruses was tested in patients with acute gastroenteritis by using conventional duplex reverse transcription (RT)-PCR and electrophoresis. Diarrheal fecal samples were collected from 9,597 patients at local hospitals in Seoul. The prevalence of astroviruses was 1.0% (94/9,597 patients; mostly infants), and that of sapoviruses was 0.1% (14/9,597 patients). Age- and gender-wise analyses were carried out on 29 astrovirus-positive patients having complete information on file regarding their age, gender, and other particulars. The results were higher in patients of ages 0 to 14 yr, and 69.0% of the astrovirus-positive patients were females, of which 69.2% were infants (0 to 12 months), and 61.5% were 1-4 yr old. Notably, in the case of 5 to 78-yr-old acute gastroenteritis patients, 100% were females.

Genotyping of gastroenteric viruses in hospitalised children: first report of norovirus GII.21 in Brazil

This retrospective study (April-September 2003) was designed to investigate the roles of the main viruses responsible for cases of acute infantile gastroenteritis in hospitalised children up to two years of age. The viruses were identified in 64.7% (88/136) of the cases and the detection rates of rotavirus A (RVA), norovirus (NoV) and astrovirus were 41.9% (57/136), 30.3% (24/79) and 12.7% (7/55), respectively. RVA and NoV were detected in 20 of the 24 reported nosocomial infection cases. This study identified the first circulation of the genotype NoV GII.21 in Brazil and highlights the need to establish differential diagnoses through active laboratorial surveillance.

The circulation of human astrovirus genotypes in the Central West Region of Brazil

Out of 1,588 faecal samples of children taken from three locations of the Central West Region of Brazil, 57 were positive for astroviruses (HAstVs) using reverse transcription-polymerase chain reaction (RT-PCR). They were genotyped by nested RT-PCR and/or genomic sequencing. HAstV-1 (42.8 percent), HAstV-2 (23.2 percent), HAstV-3 (3.6 percent), HAstV-4 (14.3 percent) and HAstVs -5, -6, -7 and -8 (1.8 percent each) were detected. In Goiânia and Campo Grande, HAstV-1 was the most frequently detected genotype while in Brasília (DF) it was HAstV-2. Shifts in the circulation of astrovirus genotypes were observed in DF and Campo Grande. All samples collected by rectal swabs were viral negative. The astrovirus genotypes were detected in all age groups and there was no correlation between genotype and age group.

Molecular characterization of astrovirus in stool samples from children in São Paulo, Brazil

The purpose of this study was to characterize astrovirus in faecal samples collected from children with and without diarrhea in São Paulo, Brazil, grouped into two sets: EPM and HU. Detection and genotyping were carried out using reverse transcription nested polymerase chain reaction (RT-PCR) with specific primers directed towards the genome open reading frame 2 (ORF2). Results for EPM set showed that 66/234 (28.2 percent) were positive: 28/94 (29.7 percent) from children with acute diarrhea, 14/45 (31.1 percent) with persistent diarrhea, and 9/55 (16.3 percent) from control individuals. No data was available for 15/40 (37.5 percent) of samples. Mixed infections with other viruses were found in 33 samples. In the HU, 18/187 (9.6 percent) were positive: 12/158 (7.6 percent) from individuals with acute diarrhea and 6/29 (20.7 percent) from control children. Four samples were mixed with other viruses. Out of 66 astrovirus positive EPM samples, 18 (27.2 percent) were characterized as human astrovirus type-1 (HAstV-1), two (3.0 percent) as HAstV-2, two (3.0 percent) as HAstV-3, and three (4.5 percent) as HAstV-8. Among 18 astrovirus positive HU samples, one (5.5 percent) was characterized as HAstV-1, six (33.3 percent) as HAstV-2, and one (5.5 percent) as HAstV-8. Two HAstV-8 genotyped samples were further confirmed by nucleotide sequencing. Our results shows that astroviruses are circulating in a constant manner in the population, with multiple serotypes, in higher frequency than it was described for other Brazilian regions. For the first time in Sao Paulo, Brazil, it was shown that astroviruses play an important role in children gastroenteritis, as described for most locations where they were detected.

First detection of a human astrovirus type 8 in a child with diarrhea in Belém, Brazil: comparison with other strains worldwide and identification of possible three lineages

This study describes the genetic relationships of the first human astrovirus type-8 (HAstV-8) detected in Belém-Brazil, during a public hospital-based study. This strain was compared with other HAstV-8 strains identified elsewhere which have sequences available at GeneBank. The regions ORF1a (primers Mon348/Mon340) and ORF2 (primers Mon269/Mon270) were analyzed by nucleotide sequencing and a high similarity rate was observed among the Belém strain and other HAstV-8 strains. In ORF1a, homology values of 93-100 por cento were detected, and in ORF2 96-99 por cento. Considering the sequence variation (7 por cento) observed in ORF2 region, it was suggested that HAstV-8 strains could be divided in three different lineages.

Astrovirus infection in children living in the Central West region of Brazil

This study presents data regarding the circulation of astrovirus in Goiânia-GO and Brasília-DF. These viruses were detected in fecal samples from hospitalized children up to five years old with and without acute gastroenteritis. A total of 1244 fecal samples were collected in two periods, 1994 to 1996 (Brasília) and 1998 to 2002 (Goiânia and Brasília), and were analyzed for viral RNA using the reverse transcription-polymerase chain reaction (RT-PCR). Positivity rates of 4.3 and 0.5 percent for astrovirus were observed in children with acute gastroenteritis and those without gastroenteritis, respectively. Among children with gastroenteritis no statistically significant difference was seen with regards to viral positivity rates in relation to gender and age. However, a higher incidence rate was observed for children from Brasília aged 36 months or more. Overall, astroviruses occurred predominantly from September to March in the two cities, suggesting a seasonal pattern for these viruses which coincides with the highest relative air humidity period. The results of this study highlight the importance of astrovirus as an etiologic agent of acute gastroenteritis in children of the Central West region of Brazil.