Epidemiology of enteric adenoviruses 40 and 41 in acute gastroenteritis in infants and young children in the Tokyo area

Proteomic analysis of A-549 cells infected with human adenovirus 40 by LC-MS

Human Adenoviruses (HAdVs) are etiological agents of different syndromes such as gastroenteritis, cystitis, ocular, and respiratory diseases, and infection by these viruses may cause alterations in cellular homeostasis. The objective of the study was the proteomic analysis of A-549 cells infected with HAdV-40 using LC-MS. At 30 h of infection, the quantitative analysis revealed 336 differentially expressed proteins. From them, 206 were induced (up-regulated) and 130 were suppressed (down-regulated). The majority of up-regulated proteins were related to energy, cellular organization, stress response, and apoptosis pathways. It was observed alteration of cell metabolism with increase of the glycolytic pathway, β-oxidation, and respiratory chain. Also, the results suggest cytoskeleton reorganization and apoptosis induction. The data can improve knowledge about the replication of HAdV-40 in cell culture considering the proteins related to distinct metabolic pathways induced by viral infection in A-549 cells.

Evolution in fecal bacterial/viral composition in infants of two central African countries (Gabon and Republic of the Congo) during their first month of life

Few studies have analyzed the gut microbiota of child in unindustrialized countries, but none during the first month of life. Stool samples were collected from healthy newborns in hospitals of Gabon (n = 6) and Republic of the Congo (n = 9) at different time points during the first month of life: meconium, day 2 (D02), day 7 (D07) and day 28 (D28). In addition, one fecal sample was collected from each mother after delivery. Metagenomic sequencing was performed to determine the bacterial communities, and multiplex real-time PCR was used to detect the presence of seven enteric viruses (rotavirus a, adenovirus, norovirus I and II, sapovirus, astrovirus, enterovirus) in these samples. Bacterial diversity was high in the first days of life, and was dominated by the genus Prevotella. Then, it rapidly decreased and remained low up to D28 when the gut flora was composed almost exclusively of strictly anaerobic bacteria. Each infant’s fecal bacterial microbiota composition was significantly closer to that of their mother than to that of any other woman in the mothers’ group, suggesting an intrauterine, placental or amniotic fluid origin of such bacteria. Moreover, bacterial communities differed according to the delivery mode. Overall, the bacterial microbiota communities displayed a similar diversification and expansion in newborns within and between countries during the first four weeks of life. Moreover, six of the fifteen infants of this study harbored enteric viruses (rotavirus, enterovirus and adenovirus) in fecal samples, but never in the meconium. A maternal source for the viruses detected at D02 and D07 can be excluded because none of them was found also in the child’s mother. These findings improve our knowledge on the gut bacterial and viral communities of infants from two Sub-Saharan countries during their first month of life.

Circulation of HAdV-41 with diverse genome types and recombination in acute gastroenteritis among children in Shanghai

Human adenovirus F (HAdV-F) is one of the major causative species detected in acute gastroenteritis in children worldwide. HAdV-F is composed of serotypes 40 and 41. Most studies have reported the prevalence of HAdV-41 and focused on its epidemiologic characteristics. In this study, seventeen samples were identified as HAdV-41 out of 273 fecal specimens from children with acute diarrhea in Shanghai. Five isolates were isolated and subjected to whole genome sequencing and analysis to characterize the genetic variation and evolution. Full genome analysis revealed low genetic variation (99.07-99.92% identity) among the isolates, and InDels are observed in the E2A gene and the hexon gene compared to the reference strain NIVD103. Phylogenetic analysis showed that all isolates mainly formed two genome-type clusters but with incongruence in the trees of whole genomes and individual genes. The recombination breakpoints of the five isolates were inferred by the Recombination Detection Program (RDP) and varied in the number and location of the recombination events, indicating different evolution origins. Overall, our study highlights the genetic diversity of HAdV-41 isolates circulating in Shanghai, which may have evolved from inter-strain recombination.

Molecular epidemiology of enteric viruses and genotyping of rotavirus A, adenovirus and astrovirus among children under 5 years old in Gabon

OBJECTIVES

This study aimed to determine the prevalence of enteric viruses causing gastroenteritis, and the circulating stains, in Gabonese children under five years old who visited health centers between March 2010 and June 2011.

METHODS

Stool specimens were collected and sent for analysis to CIRMF (Centre International de Recherches Médicales de Franceville). Stools were screened for six enteric viruses (rotavirus, adenovirus, norovirus I and II, sapovirus, human astrovirus) by means of a multiplex real-time reverse transcription polymerase chain reaction, and Rotavirus A, Adenovirus and Astrovirus were genotyped.

RESULTS

Among the 317 specimens analyzed, 193 (60.9%) were positive for at least one enteric virus. Rotavirus A (RVA) (27.1%) was the most frequently detected virus, followed by human Adenovirus (HAdV) (19.6%), Norovirus II (NoVs-II) (13.9%), Norovirus I (NoVs-I) (9.1%), Sapovirus (SaV) (9.5%) and human Astrovirus (HAstV) (6.3%). One-third of the 193 positive samples contained more than one virus. The most common Rotavirus A genotype was G6P[6]. Various HAdV serotypes were found. HAstV-1 was identified.

CONCLUSIONS

These findings improve our knowledge of circulating enteric viruses in Gabon. The emergence of unusual G6P[6] strain of rotavirus A, predominant, suggested a particular epidemiological surveillance of circulating rotavirus strains during the introduction of vaccination in Gabon.

Prevalence and molecular characterisation of human adenovirus in diarrhoeic children in Tanzania; a case control study

BACKGROUND

Human adenovirus (HAdV) causes acute diarrhoea sporadically, as well as in outbreaks. Understanding the prevalence and types of HAdV in diarrhoea is important for control and preventive measures, especially in the African region where there is a high burden of diarrhoeal disease. The present study assessed the prevalence, molecular characteristics, seasonality and associated clinical features of HAdV infection Tanzanian children below two years of age with and without diarrhoea between 2010-2011.

METHODS

Stool specimens, demographic and clinical information were collected in 690 cases and 545 controls. All stool samples were screened for HAdV-antigen using ELISA. Positive samples subsequently underwent real-time PCR and sequencing for molecular typing.

RESULTS

HAdV was detected in 37 children, corresponding to a prevalence of 3.5% (24/690) in diarrhoeic and 2.4% (13/545) in non-diarrhoeic children (P > 0.05). Among HAdV-infected children, the median age was significantly lower in diarrhoeic than in non-diarrhoeic children (10 vs. 14 months, P˂0.001). More than half of HAdV infected (54.2%) were dehydrated as compared to diarrhoeic children without HAdV (45.8%, P = 0.01). The proportion of the enteric HAdV type 40/41 in diarrhoeic and non-diarrhoeic children was (50.0%, 12/24) and (46.2%, 6/13) respectively. Other HAdV types detected were; 1, 2, 7, 18, 19 and 31. The prevalence of adenovirus was not significantly different between rainy and dry seasons. HAdV was not detected in the 33 known HIV positive children. There was no significant association between HAdV infection and gender, nutritional status of the child and parent educational level.

CONCLUSION

The present study provides further evidence of the contribution of adenovirus in causing gastroenteritis in young children, with symptomatic infection being significantly more prevalent in children below one year. We found similar prevalence of adenovirus in non-diarrhoeic children and in diarrhoeic children. This first report on molecular epidemiology of human adenovirus in Tanzania observed diversity of HAdV types that circulate the study setting. The study findings suggest that HAdV is not an important cause of diarrhoea in young HIV-positive children.

Evaluation of new immunochromatographic assay kit for adenovirus detection in throat swab: comparison with culture and real-time PCR results

A new immunochromatographic (IC) assay kit, BD Veritor System Adeno was evaluated to comparing with commercial available kit, BD Adeno Examan, cell culture, and real-time PCR using throat swab samples. Specimens were collected from 146 pediatric patients between July 2011 and January 2012. Mean age of patients was 4 years (8 months-15 years old). Patients were diagnosed with pharyngitis (n = 67), tonsillitis (n = 45), pharyngoconjunctival fever (n = 26), upper respiratory tract infection (n = 6), conjunctivitis (n = 1), or bronchitis (n = 1). Thirty-one of the patients (21.2%) had more than one disease. Among all samples, 61 (41.8%) were positive for adenovirus with BD Veritor System Adeno; 68 (46.6%) with BD Adeno Examan; 63 (43.2%) with real-time PCR; and 65 (44.5%) with cell culture. Serotype 3 (n = 41; 63.1%) was predominant among the 65 adenovirus isolates, followed by serotype 2 (n = 12; 18.5%), 1 (n = 6; 9.2%), 5 (n = 4; 6.2%), and 4 (n = 2; 3.1%). Relative sensitivity and specificity of BD Veritor System Adeno, BD Adeno Examan, and real-time PCR were 93.8% and 98.7%, 96.9% and 93.8%, and 96.9% and 100%, respectively. Positive predictive and negative predictive values for these methods were 98.4% and 95.1%, 92.6% and 97.4%, and 100% and 97.6%, respectively. The sensitivity and specificity of real-time PCR was greater than that of IC assay kits. However, IC assay kits also showed high sensitivity and specificity appropriate for clinical use.

Molecular Epidemiology of Adenovirus Infection among Pediatric Population with Diarrhea in Asia

A total of 3,577 fecal specimens from infants and children with acute gastroenteritis in Japan, Korea and Vietnam during 1998 and 2001 were tested for adenovirus by the ELISA method. Of these, adenovirus was detected in 158 (4.4%). The detection rate of adenovirus was highest in Korea (8.7%, 20/231) followed by 5.0% (100/1,991) in Japan and 2.8% (38/1,355) in Vietnam. All adenoviruses were further serotyped by PCR-RFLP. The diversity of adenovirus serotypes including Ad2, 3, 5, 8, 31, 40 and 41 was demonstrated. Worth of note was a decrease in the rate of isolation of Ad40 (7.6%, 12/158) and a concomitant increase of Ad41 (63.9%, 101/158) to become the predominant serotype. Another interesting feature of the study was the presence of Ad3 (4.0% and 30%) and Ad8 (8.0% and 20%) in Japan and Korea, respectively, which is mainly associated with keratoconjunctivitis worldwide. Our result underscored the importance of adenovirus in association with acute gastroenteritis in Asian countries.

Circulation of a novel pattern of infections by enteric adenovirus serotype 41 among children below 5 years of age in Kolkata, India

Human adenovirus of strains subgenus F (AdV F) are the most common strains detected in acute gastroenteritis cases in developing countries. Subgenus F is represented by AdV serotype 40 (AdV-40) and AdV-41. Most of the reports have described the predominance of AdV-41 in acute gastroenteritis cases. To gain insight into the epidemiology and genetic variation of AdV-41 strains, we analyzed 1,053 stool specimens from children with diarrhea. Among them, 42 (4.0%) and 56 (5.3%) were positive for enteric adenovirus 40/41 by enzyme-linked immunosorbent assay (ELISA) and PCR, respectively. For 1,305 asymptomatic children, 9 (0.7%) and 22 (1.7%) samples were positive for enteric adenovirus 40/40 by ELISA and PCR, respectively. The age distribution revealed a higher frequency (90%) in children <24 months of age. AdV F infection was observed at a low frequency throughout the year, with an increased incidence occurring during February and March. Sequence analysis of one to three hypervariable regions (HVRs) of the hexon genes of 16 representative AdV-41 strains in this study confirmed circulation of a unique strain with genomic type cluster 1 (GTC1)/GTC2. However, sequence analysis of the fiber genes of these strains confirmed 15 amino acid deletions from the 15th repeat motif of the shaft region. The existence of two GTCs reflects the accumulation of amino acid mutations in the HVR of the hexon gene. The novel AdV-41 strain might follow the same infection pattern as AdV-40. There is no significant variation in the sequences of hexon and fiber genes among strains from symptomatic and asymptomatic children. Our data confirm the circulation of an AdV-41 strain with a novel pattern in Kolkata, India, among children below 5 years of age.

Enhancement of enteric adenovirus cultivation by viral transactivator proteins

Human enteric adenoviruses (HAdVs; serotypes 40 and 41) are important waterborne and food-borne pathogens. However, HAdVs are fastidious, are difficult to cultivate, and do not produce a clear cytopathic effect during cell culture within a reasonable time. Thus, we examined whether the viral transactivator proteins cytomegalovirus (CMV) IE1 and hepatitis B virus (HBV) X promoted the multiplication of HAdVs. Additionally, we constructed a new 293 cell line expressing CMV IE1 protein for cultivation assays. We analyzed the nucleic acid sequences of the promoter regions of both E1A and hexon genes, which are considered to be the most important regions for HAdV replication. Expression of either HBV X or CMV IE1 protein significantly increased the promoter activities of E1A and hexon genes of HAdVs by as much as 14-fold during cell cultivation. The promotion of HAdV expression was confirmed by increased levels of both adenoviral DNA and mRNA expression. Finally, the newly developed 293 cell line expressing CMV IE1 protein showed an increase in viral DNA ranging from 574% to 619% compared with the conventional 293 cell line. These results suggest that the newly constructed cell line could be useful for efficient cultivation and research of fastidious HAdVs.

Quantitative detection of human adenoviruses in wastewater and combined sewer overflows influencing a Michigan river

Enteric viruses are important pathogens found in contaminated surface waters and have previously been detected in waters of the Great Lakes. Human adenoviruses were monitored because of their high prevalence and persistence in aquatic environments. In this study, we quantified adenoviruses in wastewater, surface water, and combined sewer overflows (CSOs) by real-time PCR. Between August 2005 and August 2006, adenovirus concentrations in raw sewage, primary-treated effluent, secondary-treated effluent, and chlorinated effluent from a wastewater treatment plant in Michigan were examined. CSO samples (n = 6) were collected from a CSO retention basin in Grand Rapids, MI. Adenoviruses were detected in 100% of wastewater and CSO discharge samples. Average adenovirus DNA concentrations in sewage and CSOs were 1.15 x 10(6) viruses/liter and 5.35 x 10(5) viruses/liter, respectively. Adenovirus removal was <2 log(10) (99%) at the wastewater treatment plant. Adenovirus type 41 (60% of clones), type 12 (29%), type 40 (3%), type 2 (3%), and type 3 (3%) were isolated from raw sewage and primary effluents (n = 28). Six of 20 surface water samples from recreational parks at the lower Grand River showed virus concentrations above the real-time PCR detection limit (average, 7.8 x 10(3) viruses/liter). This research demonstrates that wastewater effluents and wastewater-impacted surface waters in the lower Grand River in Michigan contain high levels of viruses and may not be suitable for full-body recreational activities. High concentrations of adenovirus in these waters may be due to inefficient removal during wastewater treatment and to the high persistence of these viruses in the environment.

Molecular epidemiology of adenovirus infection among infants and children with acute gastroenteritis in Dhaka City, Bangladesh

A total of 917 fecal specimens collected from infants and children with acute gastroenteritis in Dhaka City, Bangladesh during 2004-2005 were examined for the presence of adenoviruses by PCR. Adenoviruses were identified in 17 of 917 (1.9%) specimens. Detected adenoviruses were subjected to molecular genetic analysis by sequencing method. Adenoviruses detected in this study were classified into three serotypes, namely Ad9, Ad10 and Ad40. Of these, Ad40 was predominant, followed by Ad9 and accounted for 42% (7 of 17) and 36% (6 of 17), respectively. This is the first report of acute gastroenteritis attributed to Ad9 and Ad10 in Dhaka City, Bangladesh. Another interesting feature of the study was absence of Ad41 serotype. Our results clearly indicated that adenovirus infections were most commonly observed in winter season (October 2004 through January 2005) and in rainy season (May 2005 through July 2005) in Dhaka City. The most common clinical symptoms of adenovirus-infected patients were dehydration (94%), abdominal pain (59%) and vomiting (30%). To our knowledge, this is the first 1-year molecular epidemiological research of adenovirus infection in Bangladesh.

Waterborne adenovirus

Adenoviruses are associated with numerous disease outbreaks, particularly those involving d-cares, schools, children's camps, hospitals and other health care centers, and military settings. In addition, adenoviruses have been responsible for many recreational water outbreaks, including a great number of swimming pool outbreaks than any other waterborne virus (Gerba and Enriquez 1997). Two drinking water outbreaks have been documented for adenovirus (Divizia et al. 2004; Kukkula et al. 1997) but none for food. Of the 51 known adenovirus serotypes, one third are associated with human disease, while other infections are asymptomatic. Human disease associated with adenovirus infections include gastroenteritis, respiratory infections, eye infections, acute hemorrhagic cystitis, and meningoencephalitis (Table 2). Children and the immunocompromised are more severely impacted by adenovirus infections. Subsequently, adenovirus is included in the EPA's Drinking Water Contaminant Candidate List (CCL), which is a list of unregulated contaminants found in public water systems that may pose a risk to public health (National Research Council 1999). Adenoviruses have been detected in various waters worldwide including wastewater, river water, oceans, and swimming pools (Hurst et al. 1988; Irving and Smith 1981; Pina et al. 1998). Adenoviruses typically outnumber the enteroviruses, when both are detected in surface waters. Chapron et al. (2000) found that 38% of 29 surface water samples were positive for infectious Ad40 and Ad41. Data are lacking regarding the occurrence of adenovirus in water in the US, particularly for groundwater and drinking water. Studies have shown, however, that adenoviruses survive longer in water than enteroviruses and hepatitis A virus (Enriquez et al. 1995), which may be due to their double-stranded DNA. Risk assessments have been conducted on waterborne adenovirus (Crabtree et al. 1997; van Heerden et al. 2005c). Using dose-response data for inhalation from Couch et al. (1966), human health risks of infection, illness and death have been determined for various adenovirus exposures. Crabtree et al. (1997) conclude that, even at an adenovirus concentration of 1 per 1,000 L of drinking water, annual risks of infection exceed the suggested risk recommendation of 1 x 10(-4) per yr (Regli et al. 1991) (Table 8). Using the same exposure and dose-response assumptions, van Heerden et al. (2005c) determined annual risks of infection to be 1-1.7 x 10(-1) for two drinking water samples from South Africa containing 1.40 and 2.45 adenoviruses per 10,000 L, respectively. This present study estimated annual risks of infection associated with varying levels of adenoviruses per 100 L (Table 9). By assuming a 2 L/d exposure and utilizing the exponential model at r = 0.4172 (Haas et al. 1993), yearly risks exceed the risk recommendation of 1 x 10(-4) at every exposure level. There are limited data regarding the removal of adenoviruses by conventional water treatment or other physical-chemical treatment processes, but studies do suggest that adenoviruses are of equal or greater sensitivity to oxidizing disinfectants, when compared to waterborne viruses (the most resistant to ultraviolet light). Data suggest that the chlorine doses applied to control other waterborne viruses are more effective against adenovirus, resulting in a greater than 4-log10 removal of adenoviruses by conventional treatment and chlorination. If treatment can achieve a 4-log10 removal of adenoviruses, then, based on the risk levels presented in Table 9, surface water concentrations should not exceed 0.5 adenoviruses per 100 L (Fig. 2). More data are needed regarding effectiveness of water treatment against adenovirus and the human-virus dose-response relationship to fully understand the role of adenovirus as a waterborne public health threat.

An outbreak of adenovirus serotype 41 infection in infants and children with acute gastroenteritis in Maizuru City, Japan

A total of 337 fecal specimens were collected from infants and children with acute gastroenteritis in Maizuru City, Japan from July 2004 to June 2005 and tested for the presence of rotavirus, norovirus, sapovirus, astrovirus, and adenovirus by RT-multiplex PCR. Among diarrheal viruses detected, norovirus was the most prevalent (13.6%, 46 of 337), followed by adenovirus (8%, 27 of 337), group A rotavirus (5%, 17 of 337), astrovirus (1.8%, 6 of 337), and sapovirus (1.8%, 6 of 337), respectively. Adenovirus was subjected to molecular genetic analysis by sequencing. Adenovirus detected in this study was classified into five serotypes, namely Ad1, Ad2, Ad3, Ad5, and Ad41. Of these, Ad41 was the most predominant serotype that accounted for 85.2% (23 of 27). It was noteworthy to point out that Ad41 infection was apparently confined only to the period of 4 months (October 2004 through January 2005). This pattern of infection implied the outbreak of Ad41 in these subjects, which was the first outbreak of acute gastroenteritis attributed to adenovirus in Maizuru City, Japan. Another interesting feature of the study was the existence of two Ad41 subtypes co-circulating in this outbreak. This report confirmed the presence of adenovirus as one of an important cause of acute gastroenteritis among Japanese infants and children.

Prevalence and characterization of enteric adenoviruses in the South of Ireland

Enteric adenoviruses have been shown to be a substantial cause of pediatric gastroenteritis in various parts of the world, and are considered to be the second most common cause of viral gastroenteritis, next to rotavirus in young children. Genetic characterization of 95 adenovirus isolates obtained from patients with acute gastroenteritis between 2002 and 2007 from the southern regions of Ireland, were characterized by PCR analysis, restriction endonuclease (RE) analysis and sequencing analysis. All isolates were found to be of adenovirus type 41 origin. Genetic analysis of seven hypervariable regions (HVRs) located within the hexon gene has revealed a high level of amino acid sequence homology in samples over the course of this study, with a very close relationship to the D22 genome type. The D22 genome type has been detected in several other countries, thus suggesting Irish isolates have common genome types with other stains worldwide. This is the first such study undertaken in the south of Ireland, to type and genetically characterize adenoviral gastroenteritis isolates, and has revealed a high level of conservation within the isolated analyzed.

Molecular epidemiology of subgenus F adenoviruses associated with pediatric gastroenteritis during eight years in Hiroshima Prefecture as a limited area

We have studied the prevalence of the subgenus F adenoviruses and the molecular characteristics of adenovirus type 41 in Hiroshima Prefecture, Japan, as a limited area during the period of 1997-2004. Subgenus F adenoviruses were detected in 30 (3.4%) of 892 fecal specimens by enzyme immunoassay (EIA), and 80.0% (24 of 30) of positive patients were <36 months old. One (3.3%) and 29 (96.7%) of the 30 EIA-positive specimens were adenoviruses type 40 (Ad40) and 41 (Ad41), respectively. The genomes of Ad41 strains amplified by PCR were divided into two genomic type clusters (GTC1 and GTC2) based on the hexon gene as described by Li et al. (J Clin Microbiol 42: 4032-4039, 2004.). Twenty-one (95.5%) of 22 Ad41 strains detected between 2000 and 2004 belonged to GTC1, whereas all seven strains detected between 1997 and 1999 belonged to GTC2. These genomic typings were the same for the hexon and fiber genes except for one strain. This strain contained a hexon gene belonging to GTC1 and a fiber gene belonging to GTC2 and was considered to be a recombinant between adenoviruses of these types.

Chromatography paper strip sampling of enteric adenoviruses type 40 and 41 positive stool specimens

BACKGROUND

The enteric subgroup F adenoviruses type 40 (Ad40) and 41 (Ad41) are the second most important cause of acute infantile gastroenteritis after rotaviruses. Repeated community outbreaks have been associated with antigenic changes among the Ad40 and Ad41 strains due to host immune pressure. Therefore large field epidemiological surveys and studies on the genetic variations in different isolates of Ad40 and Ad41 are important for disease control programs, the design of efficient diagnostic kits and vaccines against subgroup F adenoviruses. A novel method using sodium dodecyl sulphate SDS/EDTA-pretreated chromatography paper strips was evaluated for the collection, storage and shipping of Ad40/41 contaminated stool samples.

RESULTS

This study shows that adenoviral DNA can be successfully detected in the filter strips by PCR after four months storage at -20 degrees C, 4 degrees C, room temperature (20-25 degrees C) and 37 degrees C. Furthermore no adenoviral infectivity was observed upon contact with the SDS/EDTA-pretreated strips.

CONCLUSIONS

Collecting, storing and transporting adenovirus type 40 and 41 positive stool samples on SDS/EDTA-pretreated chromatography filter strips is a convenient, biosafe and cost effective method for studying new genome variants and monitoring spread of enteric adenovirus strains during outbreaks.

Viruses causing gastroenteritis

Acute gastroenteritis is one of the most common diseases in humans worldwide. Viruses are recognized as important causes of this disease, particularly in children. Since the Norwalk virus was identified as a cause of gastroenteritis, the number of viral agents associated with diarrheal disease in humans has steadily increased. Rotavirus is the most common cause of severe diarrhea in children under 5 years of age. Astrovirus, calicivirus and enteric adenovirus are also important etiologic agents of acute gastroenteritis. Other viruses, such as toroviruses, coronaviruses, picobirnaviruses and pestiviruses, are increasingly being identified as causative agents of diarrhea. In recent years, the availability of diagnostic tests, mainly immunoassays or molecular biology techniques, has increased our understanding of this group of viruses. The future development of a safe and highly effective vaccine against rotavirus could prevent, at least, cases of severe diarrhea and reduce mortality from this disease.

Incidence of enteric adenovirus gastroenteritis in Iranian children

BACKGROUND

Enteric adenoviruses, i.e. adenovirus 40 (Ad40) and adenovirus 41 (Ad41), have been shown to be a substantial cause of pediatric gastroenteritis in various parts of the world, but no data are available for Iran.

OBJECTIVE

The present study was performed to determine the incidence of enteric adenoviruses in children presenting to the Children's Medical Center with gastroenteritis in Iran.

STUDY DESIGN

Stool specimens from 872 children less than 7 years of age attending the Children's Medical Center in Tehran, Iran, with gastroenteritis were tested for the presence of Ad40, Ad41, and adenovirus-genus by a monoclonal antibody-based enzyme immunoassay.

RESULTS AND CONCLUSION

6.7% of stool specimens contained enteric adenoviruses (3.3% Ad40 and 3.4% Ad41) and 2.0% nonenteric adenoviruses. Mean ages of Ad40, Ad41 and NEAd-positive children were 21, 19 and 29 months, respectively. Among the adenovirus-positive patients, 53.9% were male and 46.1% female. Watery diarrhea was present in 86.4% of children infected by adenoviruses. In conclusion, for the first time, we demonstrated the presence of enteric and nonenteric adenoviruses in a considerable proportion of stool samples from Iranian children with gastroenteritis.

Local succession of adenovirus strains in pediatric gastroenteritis

Assessment of the current incidence of different adenovirus types in local gastroenteritis involved the examination of over 1,000 stool specimens annually from 1988-1992. Adenoviruses were detected by electron microscopy and/or cell culture in 32% of the specimens in which a viral pathogen was detected. The identification of every adenovirus isolate to type by neutralization with specific antisera against the first 6 types and by restriction analysis of nonneutralized isolates was started in 1990. Samples from 1988 and 1989 were examined retrospectively. Adenovirus strains were compared to those isolated in a study between 1980-1983. Enumeration of individual adenovirus types revealed a number of trends, demonstrating that rapid changes in the local incidence of several strains were occurring in Manitoba. The incidence of adenovirus type 40 (Ad40) as a cause of gastroenteritis was found to have fallen dramatically in recent years. The predominant cause of gastroenteritis in Manitoba is a variant strain of Ad41, increasing in predominance each year and now responsible for over a third of the symptomatic cases examined since 1990. The majority of restriction site differences of the Ad41 variant strain from the prototype strain Tak were mapped to the hexon and fiber genes, both of which code for the neutralizable external viral epitopes. The probability of the observed pattern of mutations occurring by chance was calculated as P < 0.0005, indicating a strong pressure for selection of these immunologically significant alterations to the viral proteins responsible for cell attachment.(ABSTRACT TRUNCATED AT 250 WORDS)

Patients with enteric adenovirus gastroenteritis admitted to an Australian pediatric teaching hospital from 1981 to 1992

During the period 1981 to 1992, 4,473 fecal specimens collected from children hospitalized with acute gastroenteritis at the Royal Children's Hospital, Melbourne, Australia, were examined by electron microscopy. A monoclonal antibody enzyme immunoassay for enteric adenovirus (EAd) types 40 (Ad40) and 41 (Ad41) was used when adenoviruses were visualized. Fecal samples were positive for adenovirus by both electron microscopy and enzyme immunoassay in 138 patients (3.1%). Ad40 was identified in 19 children (14%), and Ad41 was identified in 119 children (86%). These EAd were identified during each of the 12 years surveyed. EAd were present year-round, but the annual number of hospitalizations was not constant. Yearly prevalence varied from 0.7% (1981) to 6.5% (1985). This was associated with monthly fluctuations in Ad41 activity, with overall peak monthly prevalence in May (late autumn). By contrast, Ad40 numbers remained low and constant year-round. The frequency of Ad41 relative to Ad40 increased from 25% in 1981 to exceed 75% after 1983. Children admitted with EAd infection were more likely to have diarrhea for more than 5 days (P < 0.001) but less likely to be febrile or dehydrated (P < 0.05) than children with rotavirus infection. EAd are responsible for enteric symptoms of only a fraction of hospitalized children with infectious diarrhea but result in a more-protracted illness than rotavirus. Their relationship to persistent diarrhea requires further investigation.

Recognition of adenovirus types in faecal samples by southern hybridization in South Australia

The distribution of adenovirus types in faecal samples of patients with suspected viral gastroenteritis from South Australia was determined during the 12-month period, July 1991-June 1992. There were 3299 samples tested and 226 (6.9%) were positive for adenovirus by enzyme immunoassay. Of these 226 samples, 154 (68%) were typed directly using virus DNA extracted from the faecal samples according to the Sma I, Hind III and BstE II restriction patterns and Southern hybridization analysis with pooled viral genomic DNA probes. In this group, 86% of the samples were from patients who were < 3 years of age. Enteric adenovirus types 40 and 41 accounted for 20 and 40% respectively, of these samples, and types 1, 2, 3, 5, 6, 7 and 31 comprised the remainder. Type 40 was detected mainly in the winter and spring periods, and type 41 predominated in the autumn period. The majority of the non-enteric types were found during the late winter and spring periods.

Adenoviruses isolated in the Stockholm area during 1987-1992: restriction endonuclease analysis and molecular epidemiology

Adenoviruses recovered from the northern Stockholm area during 1987-1992 have been subjected to restriction endonuclease analysis. Adenoviruses of all subgenera (A-F) were represented and a considerable degree of serotype variation was seen, e.g. the rarely encountered subgenus A viruses were frequently isolated in the present study. Of 16 subgenus A isolates, Ad31 predominated with 12 strains which were equally distributed into the DNA-variants D2 and D7. Analysis of 38 Ad3 isolates revealed four DNA-variants: D1, D3, D10, and "Sto1". The ten Ad7 isolates belonged all to the DNA-variant D5 of Ad7. Of 27 Ad1 strains, 11 belonged to D10, followed by the DNA-variants D4 and D7 with four strains each. Among Ad2 isolates, D2 or D2-like strains prevailed (23/28). Of six Ad5 strains, three belonged to the DNA-variant D2. The most notable subgenus D event was a nosocomial outbreak of keratokonjunctivitis due ot Ad19a. In addition, a collection of heterogenous subgenus D strains was detected, most of which untypable by RE-analysis. Among the six Ad4 isolates of subgenus E, both genomic clusters (p and a, respectively) of Ad4 were recognized. Concerning the clinical important subgenus F adenoviruses, only two strains of Ad40 were detected as compared to 12 strains of Ad41, all of which ascribed to the DNA-variant D12 of Ad41.

Detection, typing, and subtyping of enteric adenoviruses 40 and 41 from fecal samples and observation of changing incidences of infections with these types and subtypes

Monoclonal antibody (MAb) preparations specific for the enteric adenoviruses of subgenus F (AdF) were generated and evaluated as typing reagents in virus neutralization tests and enzyme-linked immunosorbent assays (ELISAs). A panel of 11 genome types of adenovirus 40 (Ad40), 24 genome types of Ad41, and 47 adenovirus prototype strains was used to determine the specificities of the MAbs in the two assays. In this way two MAbs, MAb 40-1 (anti-Ad40) and MAb 41-1 (anti-Ad41) were selected. These two MAbs showed strict type specificity in both assays. A third MAb reacted in an ELISA with all 47 human adenovirus types. With two other MAbs, three antigenic subtypes of Ad41 could be distinguished by their reactivities in virus neutralization tests and ELISAs. On the basis of the five selected MAbs, a sensitive ELISA system was developed for the direct detection and simultaneous typing and subtyping of Ad40 and Ad41 present in stool specimens. The five MAbs were also used to study the epidemiology of infections with Ad40 and Ad41 in The Netherlands in the period 1981 through 1989. It was shown that there were no significant fluctuations in the annual incidence of the cluster of enteric adenoviruses as a whole. This cluster should therefore be considered to belong to the "endemic" rather than the "epidemic" adenoviruses. The relative incidence of Ad40 infections compared with that of Ad41 infections changed considerably during the period studied; the proportion of Ad41 infections rose from about 30% in 1981 to about 95% in 1986, after which it stabilized at 90 to 95%. The proportion of one of the subtypes of Ad41 (Ad41 subtype M3) increased from about 40 to 80% in the same period.

Comparative epidemiology of rotavirus, subgenus F (types 40 and 41) adenovirus and astrovirus gastroenteritis in children

We report a 5 year prospective study of episodes of rotavirus, subgenus F adenovirus, and astrovirus gastroenteritis diagnosed by electron or immune electron microscopy in a single regional virology laboratory. Of 1426 total infections, the numbers in each category were 1117 (78.3%), 254 (17.8%), and 20 (7.9%), respectively. Using restriction endonuclease analysis or immune electron microscopy, all but 20 of the subgenus F adenovirus strains were classified as type 40 (n = 50) or type 41 (n = 184). Rotavirus and astrovirus infections were more prevalent in winter than summer, whereas subgenus F (either type 40 and 41) adenoviruses showed no seasonal variation in prevalence. The ratio of type 40 to all typable subgenus F adenoviruses declined between 1984 and 1986 and then increased again. Adenoviruses were relatively more important as causes of viral gastroenteritis in infants aged less than 6 months than in toddlers aged 12 months or more, but even in young infants more rotavirus than adenovirus infections were diagnosed. Our data confirmed the epidemiological differences between rotavirus, subgenus F adenovirus and rotavirus gastroenteritis and documented the shared epidemiological characteristics of type 40 or 41 adenovirus infections.

Epidemiology of enteric adenovirus infection in prospectively monitored Argentine families

To examine the role of enteric adenoviruses (EAV) in an urban area of Buenos Aires (Argentina), we prospectively studied faecal samples from 49 families of newborns. These were monitored weekly for diarrhoea for 2 years. A total of 180 samples from cases of diarrhoea and 766 samples obtained during diarrhoea-free periods were studied by dot-blot hybridization with an EAV-specific DNA probe. EAV were found in 6/180 (3.3%) cases of diarrhoea and 6/766 (0.8%) asymptomatic samples (P < 0.015). Incidence of EAV was 3.9 cases per 100 person-years in children < 60 months old. EAV-related diarrhoeas were slight and of short duration. In addition, 129 faeces from hospital out-patients, 1-30 months old, were also studied. EAV was identified in 7/129 cases (5.4%). These cases were 9.5 +/- 3.5 months old and the diarrhoea was mild or severe, of 3 +/- 1.5 days of duration. We suggest that EAV are low-risk causes of diarrhoea under natural conditions, although a few children may develop more severe diarrhoea. The diagnosis of EAV needs to be considered in these patients.