Tracking novel adenovirus in environmental and human clinical samples: no evidence of endemic human adenovirus type 58 circulation in Córdoba city, Argentina.

In recent years, several types of human adenovirus (HAdV) have arisen from the recombination between two or more previously known HAdV types, but their epidemiology is poorly understood. In this study, we investigated the circulation of HAdV-58, a recently described HAdV isolated from an HIV-positive patient in Córdoba city, Argentina. For this purpose, a 30-month survey was conducted to study the presence of this type of adenovirus in sewage samples collected at the inlet from a wastewater treatment plant in Córdoba city, Argentina. Complementarily, the virus was sought in stools of HIV-positive patients. Although HAdVs were detected in human stool samples and in a high percentage of sewage samples, no evidence of HAdV-58 circulation was detected. We suggest that there is no endemic circulation of HAdV-58 in the geographical local area. The trend is that the number of identified HAdVs increases over time. In this context, understanding the current circulating HAdVs may be biologically relevant.

Rotavirus seasonality in urban sewage from Argentina: effect of meteorological variables on the viral load and the genetic diversity.

In Argentina, the rotavirus disease exhibits seasonal variations, being most prevalent in the fall and winter months. To deepen the understanding of rotavirus seasonality in our community, the influence of meteorological factors on the rotavirus load and the genetic diversity in urban raw sewage from Córdoba city, Argentina were evaluated. Wastewater samples were collected monthly during a three-year study period and viral particles were concentrated by polyethylene glycol precipitation. RT-nested PCR was applied for rotavirus detection, and VP7/VP4 characterization and real-time PCR for rotavirus quantification. Both molecular techniques showed relatively similar sensitivity rates and revealed rotavirus presence in urban wastewater in cold and warm seasons, indicating its circulation in the local community all year round. However, a slight trend for rotavirus circulation was noted by real-time PCR in the fall and winter seasons, showing a significantly higher peak of rotavirus concentration at mean temperatures lower than 18°C and also higher, although not statistically different during drier weather. VP7 and VP4 gene characterization showed that G1 and P[8] genotypes were dominant, and temporal variations in genotype distribution were not observed. Rotavirus spread is complex and our results point out that weather factors alone cannot explain the seasonal quantitative pattern of the rotavirus disease. Therefore, alternative transmission routes, changes in human behavior and susceptibility, and the stability and survivability of the virus might all together contribute to the seasonality of rotavirus. The results obtained here provide evidence regarding the dynamics of rotavirus circulation and maintenance in Argentina.

Persistence of measles neutralizing antibody related to vaccine and natural infection acquired before HIV infection.

Little is known about long-lasting measles protective immunity when exposure to wild-type or vaccine measles virus precedes HIV infection. The results obtained suggest that measles immunity wanes and the lowest measles geometric mean titres (GMT) were significantly associated with measles vaccine-induced immunity in individuals that later developed HIV infection (86% prevalence, GMT 164 mIU/ml) compared to naturally induced immunity in HIV-infected adults (100% prevalence, GMT 340 mIU/ml, P = 0·0082) or non-HIV infected adults (100%, GMT 724 mIU/ml, P = 0·0001), and vaccine-induced immunity in non-HIV-infected adults (100%, GMT 347 mIU/ml, P = 0·017). The study was conducted in an area without wild-type virus circulation since 2000. The absence of virus circulating may alter the paradigm of lifelong immunity to measles virus after vaccination. As the proportion of HIV-infected individuals possessing only vaccine-induced immunity continues to grow, checking the status of measles immunity in this group is strongly recommended.

Proposal of a pathway for enteric virus groups detection as indicators of faecal contamination to enhance the evaluation of microbiological quality in freshwater in Argentina.

An environmental survey was conducted in order to assess the frequency of detection of picobirnavirus (PBV), human adenovirus (HAdV) and infective enterovirus (iEV) as indicators of faecal contamination in freshwater, and to determine their potential as reporters of the presence of other enteric viruses, such as group A rotavirus (RVA). The study was carried out over a three-year period (2013-2015) in the San Roque Dam, Córdoba, Argentina. The overall frequency detection was 62.9% for PBV, 64.2% for HAdV and 70.4% for iEV. No significant differences were observed in the rates of detection for any of these viruses through the years studied, and a seasonal pattern was not present. Whenever there was RVA detection in the samples analyzed, there was also detection of iEV and/or HAdV and/or PBV. At least one of the viral groups analyzed was demonstrated in the 100% of the samples with faecal coliforms values within the guideline limits. In this setting, especially in those samples which reveal faecal indicator bacteria within the guideline limit, we propose to carry out a pathway, involving PBV, HAdV and iEV detection in order to enhance the evaluation of microbiological quality in freshwater in Argentina. The proposed methodological strategy could report faecal contamination in water, mainly of human origin, and the condition of the matrix to maintain viral viability. In addition, the viral groups selected could report the presence of RV.

Correlation between rotavirus A genotypes detected in hospitalized children and sewage samples in 2006, Córdoba, Argentina.

Routine rotavirus A (RV-A) surveillance is based on clinical cases, so only symptomatic infections are reported. The objective of this study was to determine whether the RV-A genotypes and cold seasonal pattern described in patients with diarrhea is reflected by sewage surveillance, which could be representative of the RV-A genotypes circulating in the population. The genotype distribution of RV-A in effluent samples from a local sewage treatment plant was compared to those from local clinical cases. A total of 52 sewage samples and 70 stool specimens from children with acute non-bacterial diarrhea were collected from January to December 2006. The effluent specimens were concentrated and RNA extracts from concentrated sewage and clinical samples were genotyped for the rotavirus VP7 gene. The proportional distribution of the RV-A G-genotypes in sewage and clinical samples during the cold season was similar: G1 accounted for 26.6% of the typed sewage isolates and 28.8% of the clinical infections; G3 type accounted for 21.9% and 25.8%; G2 type 15.6% and 10.6%; G4 type 17.2% and 21.2%; G8 type 1.6% and 0%; and the G9 type 17.2% and 13.6%, respectively. A similar picture of RV-A genotype detection was obtained in sewage samples collected during the cold and warm seasons. The results indicate that there is a correlation between genotypes of RV-A isolates from human diarrheic patients and of those from sewage samples. In addition, sewage monitoring highlighted the uniform all-year RV-A circulation, which was in contrast to the peak incidence of RV-A infection in the community.

Tracking enteric viruses in green vegetables from central Argentina: potential association with viral contamination of irrigation waters.

Consumption of green vegetable products is commonly viewed as a potential risk factor for infection with enteric viruses. The link between vegetable crops and fecally contaminated irrigation water establishes an environmental scenario that can result in a risk to human health. The aim of this work was to analyze the enteric viral quality in leafy green vegetables from Córdoba (Argentina) and its potential association with viral contamination of irrigation waters. During July-December 2012, vegetables were collected from peri-urban green farms (n = 19) and its corresponding urban river irrigation waters (n = 12). Also, urban sewage samples (n = 6) were collected to analyze the viral variants circulating in the community. Viruses were eluted and concentrated by polyethylene glycol precipitation and then were subject to Reverse Transcription Polymerase Chain Reaction to assess the genome presence of norovirus, rotavirus and human astrovirus. The concentrates were also inoculated in HEp-2 (Human Epidermoid carcinoma strain #2) cells to monitor the occurrence of infective enterovirus. The frequency of detection of the viral groups in sewage, irrigation water and crops was: norovirus 100%, 67% and 58%, rotavirus 100%, 75% and 5%, astrovirus 83%, 75% and 32% and infective enterovirus 50%, 33% and 79%, respectively. A similar profile in sewage, irrigation water and green vegetables was observed for norovirus genogroups (I and II) distribution as well as for rotavirus and astrovirus G-types. These results provide the first data for Argentina pointing out that green leafy vegetables are contaminated with a broad range of enteric viruses and that the irrigation water would be a source of contamination. The presence of viral genomes and infective particles in food that in general suffer minimal treatment before consumption underlines that green crops can act as potential sources of enteric virus transmission. Public intervention in the use of the river waters as irrigation source is needed.

Quantification of human infection risk caused by rotavirus in surface waters from Córdoba, Argentina.

Fecal contamination of water is a worrying problem because it is associated with the transmission of enteric pathogenic microorganisms that can cause many infectious diseases. In this study, an environmental survey was conducted to assess the level of viral contamination by viable enterovirus and rotavirus genome in two recreational rivers (Suquía and Xanaes) of Córdoba, Argentina. Quantitative microbial risk assessment (QMRA) was calculated to estimate the risk of rotavirus infection. Water sampling was carried out during a one-year period, the presence of total and fecal coliforms was determined and water samples were then concentrated for viral determination. Cell culture and indirect immunofluorescence were applied for enterovirus detection and RT-qPCR for rotavirus quantification. Coliform bacteria levels found in Suquía River often far exceeded the guideline limits for recreational waters. The Xanaes exhibited a lower level of bacterial contamination, frequently within the guideline limits. Enterovirus and rotavirus were frequently detected in the monitoring rivers (percentage of positive samples in Suquía: 78.6% enterovirus, 100% rotavirus; in Xanaes: 87.5% enterovirus, 18.7% rotavirus). Rotavirus was detected at a media concentration of 5.7×10(5) genome copies/L (gc/L) in the Suquía and 8.5×10(0)gc/L in the Xanaes. QMRA revealed high risk of rotavirus infection in the Suquía, at sampling points with acceptable and non-acceptable bacteria numbers. The Xanaes showed significantly lower health risk of rotavirus infection but it proved to be a public health hazard. The viral occurrence was not readily explained by the levels of bacteria indicators, thus viral monitoring should be included to determine microbiological water quality. These findings provide the first data of QMRA for recreational waters in Argentina and reveal the need for public awareness of the health implications of the use of the river waters.

Rotavirus VP7-gene selection during coinfections in CaCo-2 cells.

A previous rotavirus epidemiological survey in Córdoba, Argentina, revealed an unusually high frequency of mixed G-type infections (41.5%). The genotype distribution of those mixed infections showed that the most prevalent G-type combinations were G1+G4 (65.0%), G1+G2 (12.5%), G2+G4 (3.1%) and G1+G9 (2.5%). In the present study we analyzed the competitive growth in CaCo-2 cell cultures of strains from the most frequent rotavirus G-type coinfections in order to explain some aspect of the dynamic of G-type replacement along the time. Our results indicated that G1-type was preferentially selected compared with G2 and G9-genotypes, meanwhile, G1-G4 coinfections showed an efficient co-amplification of both types. Interestingly, this mirrored the high detection rates of both genotypes as single and mixed infections (G1+G4, 65.0%) in our region. On the other hand, G2-type revealed a better amplification rate with respect to G4-type. Fluctuant rates in the prevalence of different genotypes usually observed along the time could, in part, be explained by successive replacement of strains with different growth characteristics. We hypothesized that one aspect of these different fitnesses can be measured as differential growth in culture of the strains contained in the sample of a mixed infection. Our findings here provide the first data supporting the validity of the competitive replication in vitro to better understand rotavirus G-type circulation patterns.

Picobirnavirus (PBV) natural hosts in captivity and virus excretion pattern in infected animals.

A picobirnavirus (PBV) analysis was carried out by polyacrylamide gel electrophoresis of 513 stool samples obtained from 150 animal species collected from the Córdoba city zoo. The purpose of the present study was to determine susceptible species for PBV infection, the viral excretion pattern in infected animals, and the potential association with PBV diarrheic illness. Our findings suggest that PBVs are widespread in animals and could have a similar excretion behavior to that previously detected in infected humans. No disease association with PBV infection could be demonstrated. Thus, infected animals could be persistently infected asymptomatic carriers and could serve as reservoirs of infection.

Detection of group a human rotavirus G9 genotype circulating in Córdoba, Argentina, as early as 1980.

The incidence of human rotavirus G types was determined over a 25-year period (1979-2003) by using reverse transcription-PCR (RT-PCR) to examine 519 stool specimens found to be positive for rotavirus by enzyme linked immunosorbent assay (ELISA) or polyacrylamide gel electrophoresis (PAGE). These stool samples were obtained from children under 3 years old who had been treated for acute diarrhea at public hospitals in Córdoba, Argentina. The present study describes the continued circulation of the common human G types G1 (53.8%), G2 (10.2%), G3 (4.4%), and G4 (27%), and also the detection of the unusual types G8 (0.5%) and G9 (4.2%). Genotype G9 was detected during the 1980-1988 and 1997-2003 periods at relatively low rates. Rotavirus G types distribution was independent of age (1-18 months), gender or out-patient or in-patient status. Unexpectedly, 44.6% of mixed infections were detected, involving common and unusual genotypes. Overall, 95.4% of the typed strains belonged to the most prevalent human serotypes (G1-G4) but the detection of G9 infection throughout this study period highlights the importance of this serotype as a human pathogen.