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

Enteric and non-enteric adenoviruses in children with acute gastroenteritis in Western India

Human adenoviruses (HAdVs) are the viral agents responsible for a wide spectrum of acute and chronic diseases. HAdVs are the most important etiological agents of acute gastroenteritis (AGE) and are identified as the major contributor to the deaths of diarrheal children globally. The significant rise in HAdV infections in rotavirus-vaccinated children documented in multiple studies demands continuous monitoring of HAdV strains. After the inclusion of rotavirus vaccines in the immunization schedule of India, public health research regarding prevalence, etiology, and risk factors is highly necessary for evidence-based policies and their implementation to sustain diarrhea prevention programs. In the present study, children admitted for AGE between 2013 and 2016 in seven different hospitals in Maharashtra and Gujrat states of Western India were subjected for investigation. HAdVs were found in 5.2% of the fecal specimens with the dominance of species-F (52.4%) strains, followed by the occurrence of non-enteric adenoviruses of species A (17.4%), C (11.4%), B (8.2%), and D (3.2%). The species-F strains were predominant in Ahmadabad (78.5%), Mumbai (61.5%), and Surat (57.1%) cities, followed by species-A strains. In Pune city, species B strains were detected in all HAdV patients, with none of the species A strains. Clinically, patients infected with enteric and non-enteric HAdV strains were indistinguishable. However, a high viral load was observed in species-F specimens as compared to non-species-F. The present study on fecal specimens collected in the pre-rotavirus vaccination era from hospitalized AGE patients will be important for future comparative analysis to know the exact impact of vaccination in children of Western India.

Molecular analysis of human adenoviruses in hospitalized children <5 years old with acute gastroenteritis in Tehran, Iran

Human adenoviruses (HAdVs), especially AdV-40 and 41, are common causes of nonbacterial sporadic and outbreak gastroenteritis in children. The present study aimed to describe the frequency and genetic analysis of HAdVs in hospitalized children <5 years old with acute gastroenteritis. A total of 376 stool samples obtained from June 2015 to December 2017 were investigated for the presence of HAdVs by polymerase chain reaction. The HAdV DNA was detected in 16 (4.3%) out of 376 stool samples. Based on the hexon hypervariable region (HVR), B, C, and F HADV species including five types HAdV-1, 2, 3, 6, and 41 were identified, among which enteric AdV species F (EAdV-41) was the most dominant. Moreover, our findings showed the presence of genomic type cluster 1 (GTC1) pattern in Iranian type 41 strains, which was closely similar to the D1 prototype strain (Tak) and D28. In this regard, a recombination was found in AdV-41 strains presenting the hexon sequence that belonged to GTC1, while fiber sequence clustered with GTC2.

Molecular characterization of enteric adenovirus genotypes 40 and 41 identified in children with acute gastroenteritis in Kolkata, India during 2013-2014

Human enteric adenovirus (HAdV) belonging to species F is one of the most common pathogens responsible for infantile gastroenteritis worldwide. This study was initiated to estimate prevalence and types of HAdV among children below 5 years of age seeking health care facility for treatment of diarrhea in Kolkata, Eastern India. A total of 1,562 stool specimens were tested during 2013-2014 and among them, 185 (11.8%) were positive for enteric HAdV. Maximum number of positive cases were observed among children between 6 and 12 months of age (13.9%). HAdV infection occurred at a low frequency throughout the year, with an increased incidence in the month of March-July in both the years. Among HAdV positive samples (n = 185), 44.8% showed coinfection with rotavirus. Genotyping based on hypervariable region of hexon and partial shaft region of fiber genes, revealed prevalence of HAdV-40 over HAdV-41 genotype during this study period. Nucleotide sequence analysis of HAdV-40 strains exhibited more than 99% similarity among themselves and 98.5% with the prototype strain Dugan. Sequence analysis of six hypervariable regions (HVRs) of hexon genes from all the HAdV-41 strains revealed co-circulation of both genome type cluster 1(GTC1) and GTC2. The presence of both types of GTCs reflects accumulation of amino acid (aa) mutations in HVR of hexon gene. A recombination event was evident in a subset of HAdV-41 strains where hexon gene belonged to GTC1 whereas, fiber gene clustered with GTC2. Sequence analysis of fiber gene shaft region of HAdV-41 strains revealed 15 aa deletion from the 15th repeat motif. J. Med. Virol. 89:606-614, 2017. © 2016 Wiley Periodicals, Inc.

Elution Is a Critical Step for Recovering Human Adenovirus 40 from Tap Water and Surface Water by Cross-Flow Ultrafiltration

This paper examines the recovery of the enteric adenovirus human adenovirus 40 (HAdV 40) by cross-flow ultrafiltration and interprets recovery values in terms of physicochemical interactions of virions during sample concentration. Prior to ultrafiltration, membranes were either blocked by exposure to calf serum (CS) or coated with a polyelectrolyte multilayer (PEM). HAdV 40 is a hydrophobic virus with a point of zero charge between pH 4.0 and pH 4.3. In accordance with predictions from the extended Derjaguin-Landau-Verwey-Overbeek theory, the preelution recovery of HAdV (rpre) from deionized water was higher with PEM-coated membranes (rpre (PEM) = 74.8% ± 9.7%) than with CS-blocked membranes (rpre (CS) = 54.1% ± 6.2%). With either membrane type, the total virion recovery after elution (rpost) was high for both deionized water (rpost (PEM) = 99.5% ± 6.6% and rpost (CS) = 98.8% ± 7.7%) and tap water (rpost (PEM) = 89% ± 15% and rpost (CS) = 93.7% ± 6.9%). The nearly 100% recoveries suggest that the polyanion (sodium polyphosphate) and surfactant (Tween 80) in the eluent disrupt electrostatic and hydrophobic interactions between the virion and the membrane. Addition of EDTA to the eluent greatly improved the elution efficacy (rpost (CS) = 88.6% ± 4.3% and rpost (PEM) = 87.0% ± 6.9%) with surface water, even when the organic carbon concentration in the water was high (9.4 ± 0.1 mg/liter). EDTA likely disrupts cation bridging between virions and particles in the feed water matrix or the fouling layer on the membrane surface. For complex water matrices, the eluent composition is the most important factor for achieving high virion recovery.

IMPORTANCE

Herein we present the results of a comprehensive physicochemical characterization of HAdV 40, an important human pathogen. The data on HAdV 40 surface properties enabled rigorous modeling to gain an understanding of the energetics of virion-virion and virion-filter interactions. Cross-flow filtration for concentration and recovery of HAdV 40 was evaluated, with postelution recoveries from ultrapure water (99%), tap water (∼91%), and high-carbon-content surface water (∼84%) being demonstrated. These results are significant because of the very low adenovirus recoveries that have been reported, to date, for other methods. The recovery data were interpreted in terms of specific interactions, and the eluent composition was designed accordingly to maximize HAdV 40 recovery.

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.

High frequency of cultivable human subgroup F adenoviruses in stool samples from a paediatric population admitted to hospital with acute gastroenteritis

The family Adenoviridae consists of five genera of which the genus Mastadenovirus includes human viruses classified into 57 serotypes clustered into seven subgroups (A–G). Serotypes 40 and 41 (subgroup F) are specifically associated with childhood gastroenteritis and are the most common cause of acute gastroenteritis in young children after rotaviruses and noroviruses. Standard methods for laboratory diagnosis of adenovirus infection include electron microscopy (EM) and conventional cell culture (CCC), although it is widely considered that adenoviruses 40 and 41 are difficult to cultivate, such that their circulation is most likely underestimated. One hundred and ten faecal specimens from paediatric patients with gastroenteritis were confirmed positive for adenovirus by EM and/or CCC at the Virology Unit of the University Hospital of Parma, Italy, during the period January 2010–December 2012. They were analysed to determine the actual prevalence of adenovirus 40 and 41 in these patients using PCR and restriction endonuclease analysis, and to evaluate their ability to be cultivated in standard cell lines. The results showed a high prevalence of subgroup F (62.7 %), with serotype 41 (89.8 %) predominating over serotype 40 (10.2 %). Surprisingly, among the 75 adenoviruses isolated by CCC, 37 (49 %) belonged to subgroup F, suggesting a higher capacity of adenovirus 40 and 41 to replicate in cell culture than previously thought. PCR and restriction enzyme techniques provide an efficient means of diagnosing enteric adenoviruses correctly, including subgroup F adenovirus strains in young children with gastroenteritis.

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.

Coherence among different microbial source tracking markers in a small agricultural stream with or without livestock exclusion practices

Over 1,400 water samples were collected biweekly over 6 years from an intermittent stream protected and unprotected from pasturing cattle. The samples were monitored for host-specific Bacteroidales markers, Cryptosporidium species/genotypes, viruses and coliphages associated with humans or animals, and bacterial zoonotic pathogens. Ruminant Bacteroidales markers did not increase within the restricted cattle access reach of the stream, whereas the ruminant Bacteroidales marker increased significantly in the unrestricted cattle access reach. Human Bacteroidales markers significantly increased downstream of homes where septic issues were documented. Wildlife Bacteroidales markers were detected downstream of the cattle exclusion practice where stream and riparian habitat was protected, but detections decreased after the unrestricted pasture, where the stream and riparian zone was unprotected from livestock. Detection of a large number of human viruses was shown to increase downstream of homes, and similar trends were observed for the human Bacteroidales marker. There was considerable interplay among biomarkers with stream flow, season, and the cattle exclusion practices. There were no to very weak associations with Bacteroidales markers and bacterial, viral, and parasitic pathogens. Overall, discrete sample-by-sample coherence among the different microbial source tracking markers that expressed a similar microbial source was minimal, but spatial trends were physically meaningful in terms of land use (e.g., beneficial management practice) effects on sources of fecal pollution.

Detection and molecular characterization of adenoviruses in Korean children hospitalized with acute gastroenteritis

Human adenoviruses (HAdVs) are an important cause of acute gastroenteritis in children. However, few studies on the epidemiology or types of HAdVs associated with acute gastroenteritis have been conducted in Korea. Therefore, in the present study, the incidence of HAdV in 2064 stool samples from Korean children hospitalized with acute gastroenteritis (2004-2006) was assessed and the types of viruses present determined. Polymerase chain reaction, sequencing, and phylogenic analyses revealed that 113 samples (5.5%) were HAdV-positive. While HAdVs were mainly detected during July to October, no seasonal difference between the enteric and non-enteric viruses in the incidence of HAdV was observed. HAdV-41 and HAdV-40 were found in 54 (47.8%) and 3 (2.6%) HAdV-positive samples, respectively. HAdV-3, HAdV-7, HAdV-2, HAdV-31, HAdV-4, and HAdV-37 were detected in 11 (9.7%), 5 (4.4%), 2 (1.7%), 2 (1.7%), 1 (0.8%), and 1 (0.8%) of sample(s), respectively. Thus, not only enteric, but also non-enteric, HAdVs may play an important role in acute gastroenteritis in Korean children.

Assessment of the incidence of enteric adenovirus species and serotypes in surface waters in the eastern cape province of South Africa: Tyume River as a case study

TaqMan real-time PCR was used for the detection and quantitation of adenoviruses in Tyume River water samples over a 12-month period. A total of 72 samples were analysed, and 22 samples were positive for adenovirus. Of the positive samples, 18 were collected from downstream sampling points. Among the downstream sampling points, adenovirus detection rate increased with distance downstream, being 28%, 33%, and 39% for Alice, Drayini, and Manqulweni, respectively. The Alice sampling site had the highest concentrations of adenovirus ranging between 6.54 × 103 genome copies/L and 8.49 × 104 genome copies/L. The observed trend could have been expected considering the level of anthropogenic activities in areas along the lower stretch of Tyume River, with the major one being the effluent of treated and semi treated sewage from wastewater treatment facilities. Adenovirus detection was sporadic at most sampling sites. Multiplex conventional PCR was used for the detection of clinically important adenovirus species B, C, and F and their serotypes. Species C and F adenoviruses were detected in 77% and 18% of the samples, respectively. Most adenovirus positive samples were obtained from areas of increased population densities. The presence of adenoviruses may confirm the risk of its transmission to the human population.

High prevalence of species D human adenoviruses in fecal specimens from Urban Kenyan children with diarrhea

Human adenoviruses (HAdVs) cause a wide range of clinical syndromes and are classified in seven species, A-G, comprising 52 serotypes. HAdV-A31, -F40, and -F41 have been associated with diarrhea in infants and young children. In developing countries gastroenteritis is a major cause of morbidity and mortality in children and, in comparison to rotaviruses, there are no data on the HAdVs associated with diarrhea in pediatric patients in Kenya. This study investigates the prevalence and genotypes of HAdVs in 278 stool specimens (211 diarrheal; 67 non-diarrheal) from children < or =14 years of age in urban and rural areas in Kenya. Stool specimens were screened for HAdVs using a nested polymerase chain reaction and the HAdVs genotyped by sequence analysis of a conserved hexon gene fragment. HAdVs were detected in 104/278 (37.4%) of the stool specimens: 35/43 (81.4%) of diarrheal and 10/61 (16.4%) of non-diarrheal stool specimens from children in an urban hospice; 25/94 (26.6%) of diarrheal specimens from urban children and 34/80 (42.5%) of diarrheal specimens from children in a rural area. Species D HAdVs were identified as the most prevalent HAdV species in diarrheal stool specimens from urban children comprising 18/37 (48.6%) of the strains identified. In contrast HAdV species F predominated in pediatric diarrheal specimens from the rural area, being identified in 7/16 (43.8%) of the characterized strains. This study provides valuable new data on the prevalence and distribution of HAdV genotypes in diarrheal stool specimens in Kenya and Africa, and highlights the necessity for further investigations.

Isolation and characterization of adenoviruses persistently shed from the gastrointestinal tract of non-human primates

Adenoviruses are important human pathogens that have been developed as vectors for gene therapies and genetic vaccines. Previous studies indicated that human infections with adenoviruses are self-limiting in immunocompetent hosts with evidence of some persistence in adenoid tissue. We sought to better understand the natural history of adenovirus infections in various non-human primates and discovered that healthy populations of great apes (chimpanzees, bonobos, gorillas, and orangutans) and macaques shed substantial quantities of infectious adenoviruses in stool. Shedding in stools from asymptomatic humans was found to be much less frequent, comparable to frequencies reported before. We purified and fully sequenced 30 novel adenoviruses from apes and 3 novel adenoviruses from macaques. Analyses of the new ape adenovirus sequences (as well as the 4 chimpanzee adenovirus sequences we have previously reported) together with 22 complete adenovirus genomes available from GenBank revealed that (a) the ape adenoviruses could clearly be classified into species corresponding to human adenovirus species B, C, and E, (b) there was evidence for intraspecies recombination between adenoviruses, and (c) the high degree of phylogenetic relatedness of adenoviruses across their various primate hosts provided evidence for cross species transmission events to have occurred in the natural history of B and E viruses. The high degree of asymptomatic shedding of live adenovirus in non-human primates and evidence for zoonotic transmissions warrants caution for primate handling and housing. Furthermore, the presence of persistent and/or latent adenovirus infections in the gut should be considered in the design and interpretation of human and non-human primate studies with adenovirus vectors.

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.

Prospective study of etiologic agents of acute gastroenteritis outbreaks in child care centers

OBJECTIVE

To investigate the etiology of outbreaks of acute gastroenteritis (AGE) in children attending childcare centers (CCCs) in North Carolina between October 2005 and March 2007.

STUDY DESIGN

In this prospective study of outbreaks of AGE in CCCs, stool specimens from symptomatic children and environmental surface swabs were tested for adenovirus group F, astrovirus, norovirus (NoV), rotavirus group A, and sapovirus using real-time and conventional reverse transcription-polymerase chain reaction assays, and viruses were genotyped by sequencing.

RESULTS

A total of 29 AGE outbreaks were evaluated, of which 13 (45%) were caused by a single virus, including rotavirus group A (17%), NoV (10%), astrovirus (10%), and sapovirus (7%). Multiple viruses were detected in 3 outbreaks (10%). Environmental swabs from 13 of 22 outbreaks (59%) tested positive for at least 1 virus and confirmed the findings of the same virus in the fecal specimens for 10 of the outbreaks (45%).

CONCLUSIONS

This study confirms that viruses are major causes of AGE outbreak in CCCs. Our finding of widespread environmental contamination during such outbreaks suggests the need to study the effectiveness of current surface disinfectants against multiple gastroenteritis viruses in CCCs.

Adenoviruses associated with acute gastroenteritis in hospitalized and community children up to 5 years old in Rio de Janeiro and Salvador, Brazil

Acute gastroenteritis is a major source of morbidity and mortality among young children in developed and developing countries. Human adenoviruses (HAdVs), and in particular species F, are related to childhood diarrhoea worldwide. This study presents the results obtained during an investigation of HAdVs causing acute gastroenteritis in children hospitalized in Rio de Janeiro, RJ, Brazil, from April 1996 to September 2003, as well as in children with diarrhoea living in the slums of Salvador, BA, Brazil, from October 2001 to September 2003. A total of 3060 stool samples was analysed by an enzyme immunoassay for rotavirus and adenovirus (EIARA) and 61 (2%) were found to be positive. HAdV presented with low prevalence throughout the year, with a slight but not significant increase in incidence in late summer and early autumn. Children up to 2 years of age were the most frequently affected (79% of all positive samples). All positive samples were analysed further by generic and species-specific HAdV PCR protocols, confirming 100% specificity of this rapid and inexpensive EIARA. Species F was the most prevalent (65%), despite the occurrence of species A (12%), C, D and co-infection F/D (5% each) and species B and co-infections F/A, F/C and B/D (2% each). In order to type the species F strains as HAdV-40 or -41, generic PCR and a HinfI restriction digest were performed. HAdV-40 and -41 were found to represent 62% (23/37) and 38% (14/37), respectively. These results demonstrated that a combination of generic and species-specific PCRs is useful and reliable for HAdV species and type identification directly from faecal specimens. The results confirmed the endemism of human adenoviruses, mainly species F, in children as aetiological agents of diarrhoea, although the limited sensitivity of EIARA as a screening method may have underestimated their prevalence.

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.

Detection and sequence-based typing of human adenoviruses using sensitive universal primer sets for the hexon gene

The universal primer sets for identification of human adenovirus (HAdV) targeting hexon gene were designed and applied to 121 clinical samples suspected of HAdV infection. The primer sets amplified at least 20 HAdV reference strains of six species. Of these clinical samples, 81 (66.9%) samples were positive for HAdV. They were classified into 11 serotypes belonging to 5 HAdV species (B-F). The primer sets described here are sensitive and reactive to the broad spectrum of HAdV and are useful for rapid diagnosis of various HAdV infections.

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.

Characterizations of adenovirus type 41 isolates from children with acute gastroenteritis in Japan, Vietnam, and Korea

Genetic and antigenic characterizations of 70 strains of adenovirus type 41 (Ad41), isolated between 1998 and 2001 from children in Japan, Vietnam, and Korea, were done by DNA restriction enzyme (RE) analysis, sequencing analysis, and monoclonal antibody (MAb)-based enzyme-linked immunosorbent assay (ELISA). Eight genome types were observed in the present study, among which D25, D26, D27, and D28 were novel genome types. These eight genome types were divided into two genome-type clusters (GTCs) based on phylogenetic analysis of the hypervariable regions (HVRs) of the hexon. GTC1 includes D1, D25, D26, D27, and D28, and the GTC2 contains D4, D12, and D22. The amino acid homologies among the members within a GTC were 97 to 100%, whereas between the members of different GTCs the homologies were 92 to 94%. The specificity of the GTC classification was confirmed by ELISA with MAb 1F, which was selected by the Ad41 prototype Tak strain. It was found that only the isolates of GTC1 but not of GTC2 reacted with MAb 1F. These results suggest that Ad41 isolates from the three countries should be classified into two subtypes. The accumulation of amino acid mutations located in HVRs of hexon are indicative for the classification of Ad41 subtype.

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.

Human adenovirus Ad-36 promotes weight gain in male rhesus and marmoset monkeys

Although obesity has multiple etiologies, an overlooked possibility is an infectious origin. We previously identified two viruses, SMAM-1, an avian adenovirus (Ad), and Ad-36, a human adenovirus, that produce a syndrome of visceral obesity, with paradoxically decreased serum cholesterol and triglycerides in chickens and mice. In the two studies presented in this paper, we used nonhuman primates to investigate the adiposity-promoting potential of Ad-36. In study 1, we observed spontaneously occurring Ad-36 antibodies in 15 male rhesus monkeys, and a significant longitudinal association of positive antibody status with weight gain and plasma cholesterol lowering during the 18 mo after viral antibody appearance. In study 2, which was a randomized controlled experiment, three male marmosets inoculated with Ad-36 had a threefold body weight gain, a greater fat gain and lower serum cholesterol relative to baseline (P <0.05) than three uninfected controls at 28 wk postinoculation. These studies illustrate that the adiposity-promoting effect of Ad-36 occurs in two nonhuman primate species and demonstrates the usefulness of nonhuman primates for further evaluation of Ad-36-induced adiposity.

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.

Prevalence of enteric adenoviruses among children with diarrhea in four Brazilian cities

BACKGROUND

Enteric adenoviruses are related to child diarrhea and appear to be spread worldwide.

OBJECTIVES

The aim of the present study was to determine the prevalence of enteric adenovirus infection among children in four Brazilian cities.

STUDY DESIGN

stool specimens were collected from children under 5 years of age with acute diarrhea.

RESULTS AND CONCLUSIONS

Enteric adenoviruses were detected in 1.55% (n=1420) of the samples analyzed indicating the circulation of these viruses among Brazilian children in association to diarrheal disease. These agents were isolated throughout the year demonstrating no specific seasonal distribution. Also, no pattern of serotype distribution between the cities was observed.

Intra-CSF administered recombinant adenovirus causes an immune response-mediated toxicity

High doses of adenotk were injected into the cerebrospinal fluid of rats and nonhuman primates (Macaca mulatta). Vector administration was followed by ganciclovir administration for 14 days. Despite the absence of clinical symptoms, analysis of the cerebrospinal fluid (CSF) and histopathological examination of the central nervous system (CNS) of the monkeys (3 weeks after vector injection) were consistent with a viral meningitis. Immunohistochemical analysis of the inflammatory infiltrates in the monkeys revealed the presence of T and B lymphocytes, indicating a combined cellular and humoral immune response to the vector. This latter was supported by the finding of intrathecal anti-adenovirus antibody synthesis. Rats receiving high intrathecal adenotk doses showed a transient and dose-dependent clinical toxicity consisting of lethargy, hyperemic eyes and weight loss. Histopathological examination of the meninges showed a shift from polymorphonuclear infiltrates during the first post-injection days to clusters of mononuclear cells after 7 days. Acute toxicity is probably related to the early, innate immune response to the vector. In a separate experiment, high levels of IL-8 and IL-6, were measured during the first 2-3 post-injection days in the CSF of two monkeys which received intrathecal adenoLacZ. Therefore, these cytokines seem to play an important role in initiating the nonspecific immune response. In one monkey which received adenotk, recombinant adenovirus was cultured from serum samples obtained at the 7th post-injection day. At this time-point, no vector could be isolated from CSF samples. Based on these preclinical data, we recommend careful dose finding for clinical studies that aim to treat patients with leptomeningeal metastases.

Increased adiposity in animals due to a human virus

BACKGROUND

Four animal models of virus-induced obesity including adiposity induced by an avian adenovirus have been described previously. This is the first report of adiposity induced in animals by a human virus.

OBJECTIVE

We investigated the adiposity promoting effect of a human adenovirus (Ad-36) in two different animal models.

DESIGN

Due to the novel nature of the findings we replicated the experiments using a chicken model three times and a mammal model once. In four separate experiments, chickens and mice were inoculated with human adenovirus Ad-36. Weight matched groups inoculated with tissue culture media were used as non-infected controls in each experiment. Ad-36 inoculated and uninfected control groups were housed in separate rooms under biosafety level 2 or better containment. The first experiment included an additional weight matched group of chickens that was inoculated with CELO (chick embryo lethal orphan virus), an avian adenovirus. Food intakes and body weights were measured weekly. At the time of sacrifice blood was drawn and visceral fat was carefully separated and weighed. Total body fat was determined by chemical extraction of carcass fat.

RESULTS

Animals inoculated with Ad-36 developed a syndrome of increased adipose tissue and paradoxically low levels of serum cholesterol and triglycerides. This syndrome was not seen in chickens inoculated with CELO virus. Sections of the brain and hypothalamus of Ad-36 inoculated animals did not show any overt histopathological changes. Ad-36 DNA could be detected in adipose tissue, but not skeletal muscles of randomly selected animals for as long as 16 weeks after Ad-36 inoculation.

CONCLUSIONS

Data from these animal models suggest that the role of viral disease in the etiology of human obesity must be considered.

Percutaneous gene therapy using recombinant adenoviruses encoding human herpes simplex virus thymidine kinase, human PAI-1, and human NOS3 in balloon-injured porcine coronary arteries

Local intracoronary delivery of recombinant adenoviruses expressing anti-migratory or anti-proliferative proteins including human constitutive endothelial nitric oxide synthase (NOS3), plasminogen activator inhibitor 1 (PAI-1), or herpesvirus thymidine kinase (TK) (combined with ganciclovir) was used to prevent neointimal formation in porcine coronary arteries. After balloon injury of the left anterior descending (LAD) coronary artery, animals received an intramural injection of adenovirus (1.5 X 10(9) PFU) carrying either the NOS3 cDNA (AdCMVNOS3, n = 12), the PAI-1 cDNA (AdCMVPAI-1, n = 12), the TK cDNA (AdMLPItk, n = 12), or no cDNA (AdpL+, n = 12). After 28 days, morphometric analysis was performed on coronary sections from all segments demonstrating injury. The internal elastic lamina (IEL) fracture length normalized to the IEL perimeter (initial injury) and the neointimal area normalized to the vessel area (response to injury) were used to generate linear regression lines and calculate an index of stenosis for the respective treatment groups. The response to injury was significantly smaller in AdCMVNOS3- and AdMLPItk-infected animals than in AdpL+-infected animals (slopes = 0.86 +/- 0.05 and 0.69 +/- 0.07 versus 1.11 +/- 0.06, p < 0.005 and p < 0.0001, respectively) but not in AdCMVPAI-1-infected animals (slope = 1.26 +/- 0.04, p = 0.04). No viral shedding was observed and there was no acute systemic toxicity after gene transfer. An increase in neutralizing antibody titers against Ad vectors was observed without any detectable response to the transgene products (NOS3, PAI-1). Local gene transfer of NOS3 and TK may hold promise as a safe and effective adjunctive treatment to reduce neointimal formation after percutaneous coronary intervention in humans.

Human caliciviruses in acute gastroenteritis of young children in the community

Episodes of acute gastroenteritis in prospectively followed children between 2 months and 2 years of age were examined for rotaviruses, enteric adenoviruses, astroviruses, and human caliciviruses, including both Norwalk-like viruses (NLVs) and Sapporo-like viruses (SLVs), using PCR and reverse transcription (RT)-PCR assays. A virus was identified in 60% (502/832) of all episodes and in 85% of the moderately severe or severe episodes. Human caliciviruses were as common as rotaviruses, both being detected in 29% of the cases. NLVs accounted for a 20% etiologic share of all cases; the clinical picture was a moderately severe disease with vomiting as a predominant symptom. SLVs were detected in 9% of the cases, the clinical picture being a mild diarrheal disease. Astroviruses were found in 10% and enteric adenoviruses in 6% of the cases. Diagnosis with PCR and RT-PCR methods increases the detection of all gastroenteritis viruses, particularly human caliciviruses. As a group, human caliciviruses are common causative agents of gastroenteritis in children <2 years of age in Finland, and, of these, NLVs cause more severe disease than SLVs.

Antibodies to enteric adenoviruses (Ad40 and Ad41) in sera from Iranian children

BACKGROUND

There is strong epidemiologic and serologic evidence that infection with the enteric adenoviruses can result in severe gastroenteritis in children.

OBJECTIVES

This study was performed to determine the prevalence of enteric adenovirus infection in Iran.

STUDY DESIGN

One hundred and twenty-seven single sera from children up to 7 years of age, collected from healthy Iranian children in 1993-1994, were tested for antibodies to enteric adenoviruses by neutralization tests.

RESULT AND CONCLUSION

Antibodies to enteric adenoviruses have been detected in about one-half of sera. It is concluded that infection by these viruses is common among children in Iran.

Relevance of commercial diagnostic tests to detection of enteric adenovirus infections in South Africa

The prevalence of enteric adenoviruses detected by an in-house enzyme-linked immunosorbent assay (the RIVM-ELISA) ranged from 13 to 38%, and subgroup F adenoviruses comprised 86%. All subgroup F adenoviruses reacted with both RIVM anti-adenovirus type 40 (Ad40) and anti-adenovirus type 41 (Ad41) monoclonal antibodies but were not detected by Adenoclone Type 40/41 enzyme immunoassay (EIA). The correlation between the Biotrin EIA and RIVM-ELISA results was low (26%). Immunospecific tests suggest that a significant proportion of enteric adenoviruses, possibly comprising previously unidentified or emerging types, are not detected by commercial diagnostic tests in South Africa.

Adenoviruses from human immunodeficiency virus-infected individuals, including two strains that represent new candidate serotypes Ad50 and Ad51 of species B1 and D, respectively

Adenovirus (Ad) isolates from a large number of human immunodeficiency virus (HIV)-infected individuals were compared serologically and genetically with Ad isolates from immunocompetent patients. Between 1982 and 1994, stool and urine samples from 137 subjects with AIDS hospitalized in The Netherlands yielded 143 Ad strains. Forty additional Ad strains were obtained from 35 HIV-positive patients in Manchester, United Kingdom, in 1992 and 1993. Of these 183 HIV-associated Ad strains, 84% belonged to species D and 3% belonged to species C. These strains were compared with 2,301 Ad strains collected during general diagnostic examinations in The Netherlands from 1973 to 1992. Of the latter strains, 5% belonged to species D and 49% belonged to species C. Two of the Ads isolated from fecal specimens of AIDS patients represent new serotypes: candidate Ad serotype 50 (prototype strain, Wan) of subspecies B1 and candidate Ad serotype 51 (prototype strain, Bom) of species D. The DNA restriction enzyme patterns of strains Wan and Bom differed from the patterns of all established prototypes.

Infectious gastro-enteritis: an uncommon cause of diarrhoea in adult allogeneic and autologous stem cell transplant recipients

The incidence and aetiology of acute diarrhoea in 60 adult allogeneic or autologous stem cell transplant (SCT) recipients was determined in a prospective study. Stool specimens were obtained prior to SCT and on days +20, +40, +60 and +100 post transplant. Microbiological evaluation was performed for pathogenic bacteria, fungi, parasites and viruses. Forty-seven patients were evaluable of whom 31 had a total of 48 acute diarrhoeal episodes. Diarrhoea occurred in 79% of allogeneic and 47% of autologous SCT recipients (P < 0.05). Intestinal infections were found in three of 48 (6%) diarrhoeal episodes. Clostridium difficile with positive toxin was cultured twice and one stool specimen was positive for cryptosporidium. Intestinal pathogens were identified in 13 out of 172 stool specimens from asymptomatic patients and included: rotavirus (4), adenovirus (3), C. difficile, toxin positive (2), and others (4). Graft-versus-host disease was confirmed by biopsy in two of 36 episodes of diarrhoea in allogeneic patients, and in three patients a relationship between reactivation of cytomegalovirus and diarrhoea was suspected. In 40 of 48 (83%) episodes of diarrhoea no clear aetiology could be found.

Adenovirus type 41 lacks an RGD alpha(v)-integrin binding motif on the penton base and undergoes delayed uptake in A549 cells

Human adenovirus (Ad) types 2, 3 and 12 are known to interact with cell surface integrins alpha(v)beta(3) and alpha(v)beta(5) through an RGD motif carried by the penton base. This interaction is thought to augment virus entry after initial contact between the fiber and specific receptor(s). Ad40 and Ad41 are the only members of the human subgroup F adenoviruses. The penton base protein sequence of one Ad40 strain is known to carry the motif RGAD rather than RGD, suggesting that not all human adenoviruses use the above integrins for cell entry. We confirmed that different genomic variants of Ad40 all carry an RGAD motif on the penton base, and found that the Ad41 prototype and several other genomic variants of Ad41 carry the motif IGDD in place of RGAD or RGD. This region is most likely exposed on the Ad41 particle, but attempts to block Ad41 infectivity using a homologous peptide were unsuccessful. Infectivity of an Ad41 preparation as measured by fluorescent focus assay in A549 cells was highly dependent on the length of the adsorption period, indicating that fiber-mediated attachment is inefficient in these cells. Moreover, Ad41 virions adsorbed for 1 h were internalized in a semi-linear fashion over 8 h. This inefficient uptake may be a direct consequence of independence of subgroup F adenoviruses from alpha(v)beta(3) and alpha(v)beta(5) integrin-mediated endocytosis. Ad40 and Ad41 may thus have lost or may never have developed a dependence on the penton base RGD motif for entry.

Distribution of recombinant adenovirus in the cerebrospinal fluid of nonhuman primates

Gene therapy by administration of vectors into the cerebrospinal fluid (CSF) may be used in treatment of leptomeningeal metastases (cancer gene therapy) as well as in treatment of neurodegenerative disorders, traumatic injury, and chronic pain. Recombinant adenoviruses are attractive vectors for intra-CSF administration because they can efficiently transfer genes into the nonreplicating cells of the central nervous system (CNS). In addition, they can be produced in high titers and, because no producers cells are introduced, the risk of CSF obstruction by clustering cells is circumvented. However, successful application requires favorable distribution dynamics, high transduction efficiency, and long-lasting transgene expression. In this study we examined the distribution of a recombinant adenovirus containing the lacZ gene after administration into the CSF of nonhuman primates. After intraventricular and suboccipital administration, homogeneous distribution of the vector along the meninges covering the brain and spinal cord was obtained, as demonstrated by extensive and intense blue staining of cells, predominantly in the arachnoid and pia mater. In one animal we also found beta-galactosidase activity in the cervical paraspinal fat and in one of the deep cervical lymph nodes, indicating drainage of the vector or vector products with CSF into cervical lymph. This route of vector clearance from the CNS may result in antigenic presentation and an effective immune response and may explain the sixfold higher serum antibody titers after intrathecal injection of adenovirus as compared with intranasal application in Fischer rats. We conclude that distribution dynamics of recombinant adenovirus after intra-CSF administration are excellent. However, because of the immune response elicited by the virus, even after administration to the CNS, development of immunomodulating strategies remains a challenge.

Rapid shell vial culture technique for detection of enteroviruses and adenoviruses in fecal specimens: comparison with conventional virus isolation method

Detection of enteroviruses and adenoviruses mainly in fecal specimens by rapid culture with inoculation onto cell monolayers in flat-bottom tubes by centrifugation and immunofluorescence staining with genus-specific monoclonal antibodies was compared with that by the conventional virus isolation procedure. For both conventional culture and shell vial culture human lung fibroblast cells and tertiary monkey kidney cells were used. For enterovirus detection, 979 clinical specimens (916 stool specimens, 56 cerebrospinal fluid specimens, and 7 nasopharyngeal swabs) were used. Conventional culture detected 74 enterovirus isolates. A cytopathic effect compatible with the presence of an enterovirus after 3 days of incubation occurred in 25 of the 74 (34%) specimens that eventually became positive. The detection rate for enteroviruses by rapid cell culture after 2 to 3 days of incubation was 42 of 74 (57%). The genus-specific enterovirus monoclonal antibody did not react with strains of echovirus types 22 and 23 or enterovirus type 71. Rapid cell culture for the detection of adenoviruses was performed with 567 clinical specimens (536 stool specimens, 25 cerebrospinal fluid specimens, and 6 miscellaneous specimens), in which 42 adenoviruses were found by conventional culture. Nine of the 42 (21%) adenovirus isolates were detected by conventional culture within 3 days after inoculation, whereas 21 (50%) were found by rapid cell culture within 2 to 3 days. Only two of the nine specimens found to be positive for the enteric adenovirus type 41 by conventional culture as well by a type-specific enzyme-linked immunosorbent assay (ELISA) tested positive by rapid cell culture. In conclusion, the rapid shell vial assay allows the early detection and identification of enteroviruses and adenoviruses in clinical specimens but is markedly less sensitive than the conventional isolation procedure according to the eventual results of the conventional isolation procedure. Conventional cell culture remains a prerequisite for serotyping of enteroviral isolates. On the basis of the results for adenovirus type 41, the rapid detection of adenoviruses was not considered to be useful for the detection of clinically relevant adenoviruses in fecal samples.

Etiology of acute gastroenteritis in hospitalized children in Melbourne, Australia, from April 1980 to March 1993

Acute infectious diarrhea is common in children. Control requires knowledge of causes. Few comprehensive long-term studies of etiology have been undertaken in developed countries. This report is of a 13-year survey of 4,637 children from 0 to 14 years of age, admitted to a large children's hospital for treatment of gastroenteritis, in which viruses, bacteria, and parasites were sought. A recognized enteric pathogen was identified in 56.6% of children. Group A rotaviruses occurred in 39.6% of children overall and in 55% of children 12 to 23 months of age. They were a frequent cause (18.7%) of acute gastroenteritis in children under 6 months and in those aged 5 to 13 years (16%). Rotaviruses were almost entirely responsible for winter admission peaks. Enteric adenovirus types 40 and 41 (6% overall) were more frequent in children under 12 months (9.4%). Salmonella spp. (5.8%) and Campylobacter jejuni (3.4%) were more common in children over 5 years (13.1% and 6.7%, respectively). The 43.5% of cases (60% in children under 6 months) where no enteric pathogen was identified are cause for concern. The involvement of small viruses (including caliciviruses and astroviruses) may be clarified when molecular biology techniques are utilized to address this gap in our knowledge. This comprehensive 13-year study of the cause of acute infectious diarrhea in children in developed countries reinforces the importance of rotavirus and highlights a large group for whom the etiology remains unknown, an issue of particular concern with babies under 6 months of age. New techniques have the potential to identify old and new pathogens causing disease in these vulnerable infants.

Chronic intestinal infection due to subgenus F type 40 adenovirus in a patient with AIDS

A case of chronic intestinal infection due to adenovirus type 40 lasting for 13 months in a patient with AIDS is described. Adenovirus particles were detected by electron microscopy in biopsy samples taken from the duodenum 3 months after the onset of diarrhoea. The virus was identified as adenovirus type 40 in stool samples by ELISA monoclonal antibodies to adenovirus group antigen (MAd-g2) and types 40 and 41 (MA 40-1 and MA 41-1). No other enteropathogens were found. These data support a causal relationship between adenovirus 40 and the gastrointestinal symptoms of the patient. This is the first reported case of intestinal infection caused by adenovirus type 40 in a patient with AIDS.

Detection of enteric adenoviruses 40 and 41 in stool specimens by monoclonal antibody-based enzyme immunoassays

To examine the role of enteric adenoviruses (Ad40 and Ad41) in children with acute gastroenteritis, we evaluated 273 children with diarrhoea and 137 without enteric symptoms in Palermo, Italy, during an 8-month period. Stools were tested by two home-made monoclonal-based ELISAs to detected genus-specific adenovirus antigen and to type Ad40 and Ad41. Twenty-five samples (6.1%) were found to contain adenovirus, 18 of which were grown in Graham 293 and in HEp-2 cells. Ad40 and Ad41 were detected in 2.6% of children with diarrhoea and in none in the control group, while non-enteric adenoviruses were obtained from both patients (3.2%) and controls (6.5%). Samples containing Ad40 and Ad41 were positive by the virus isolation procedure in Graham and in HEp-2 cells, showing no distinct growth pattern in these cell lines. The evaluation of a latex agglutination test (Adenolex) and of a commercial ELISA (Adenoclone), respectively available for the detection of genus adenovirus antigen and for the typing of Ad40 and Ad41 suggests that both tests enable the identification of enteric adenoviruses in stool specimens, giving results comparable to our ELISAs.

Enteropathogens associated with childhood diarrhea in Italy. The Italian Study Group on Gastrointestinal Infections

BACKGROUND

Infectious diarrheal diseases remain an important cause of childhood morbidity in industrialized countries. The knowledge of the etiology and epidemiology of childhood diarrhea in a given area is needed to plan any measure designed to prevent or ameliorate diarrheal illness and to develop practice guidelines for the most appropriate stool examination procedures.

METHODS

We evaluated 618 children with diarrhea and 135 controls prospectively for viral, bacterial and parasitic enteric pathogens. Diarrheagenic Escherichia coli was identified by gene probes specific to different virulence factors. Stool filtrates were examined for the presence of free bacterial toxins by a cell culture cytotoxicity assay. Clinical and epidemiologic data were recorded and analyzed in relation to microbiologic findings.

RESULTS

Enteropathogens were identified in 59% of children with diarrhea and in 10.4% of asymptomatic controls. The agents mainly associated with disease were rotavirus (23.6%), Salmonella (19.2%) and Campylobacter (7.9%). Rotavirus was significantly more frequent among children observed as inpatients whereas Campylobacter was significantly more common in outpatients. Infections with diarrheagenic E. coli, Shigella flexneri, yersinia enterocolitica, Cryptosporidium and Giardia were observed in a limited number of patients. The clinical presentation of children was not sufficiently characteristic to permit presumptive diagnosis of a specific pathogen. conversely the presence of blood and/or leukocytes in stools had a high positive predictive value for Salmonella or Campylobacter infection.

CONCLUSION

The results of this study will be useful for planning strategies to prevent and control diarrheal diseases in our country.

Detection and typing of subgroup F adenoviruses using the polymerase chain reaction

A DNA amplification test was developed for the sensitive detection of the diarrhoea-associated subgroup F adenoviruses in clinical specimens. The test was made highly specific for serotypes 40 and 41 by using a region of the genome (the long-fiber gene) which is not significantly homologous to other human adenoviruses, but which is highly conserved between Ad40 and Ad41. A positive subgroup F adenovirus diagnosis was characterized by the presence of an amplification product of 152 base pairs, which could be digested into products of predictable length by restriction enzymes XbaI and SpeI. The viruses were typed as either Ad40 or Ad41 by digestion of the amplification product with a restriction enzyme which digested only Ad40 DNA. The specificity of the test was assessed using DNA from other adenoviruses, from human and simian cells, and from bacteria commonly found in the human intestine. There was a strong correlation between results of typing obtained with PCR and restriction enzyme typing of Ad40 and Ad41, and also positivity using subgroup F specific probes in dot blot hybridizations.

Rapid subgenus identification of human adenovirus isolates by a general PCR

In most clinical situations involving adenovirus infection, subgenus (subgroup) identification of an adenovirus isolate is as informative as a finer identification by serotype. A PCR method which allows the identification of human adenovirus isolates as members of subgenera A, B:1, B:2, C, D, E, or F is described. It is based on a simple (nonnested) PCR using primers which bind to regions immediately flanking the VA RNA-encoding regions of human adenovirus genomes. The PCR allows amplification of DNA from all 49 human adenovirus prototype strains so far described. Since there are differences in the lengths of the VA RNA-encoding regions in adenoviruses of different subgenera, it is possible to differentiate some subgenera according to the size of the PCR product determined by electrophoresis. This forms the basis of an initial broad categorization of isolates as belonging to either (i) subgenus B:1, C, D, or E or (ii) subgenus A, B:2, or F. Subgenus identification is completed by a one-step restriction enzyme digestion and gel electrophoresis. The method was assessed by blind subgenus identification of 200 miscellaneous primate adenovirus isolates prepared by the reference laboratory at Bilthoven, The Netherlands. Identification at the subgenus level by PCR correlated 91.5% with the results of serotyping. A further 5.5% of isolates were correctly identified as belonging to one of two specified subgenera. Six of the 200 identifications (3%) were unsuccessful for various reasons, including weak PCR products, intermediate strains, and mistaken primate host. The method should serve as a rapid means of confirming adenovirus cytopathic effects in laboratories performing virus culture, with simultaneous subgenus identification of the isolate. It will also have relevance as an aid to conventional serotyping for epidemiological purposes, since for all adenoviruses except those belonging to subgenus D, neutralization tests need only involve a maximum of four type-specific antisera.

Structural features unique to enteric adenoviruses

Enteric adenoviruses are important agents of pediatric gastroenteritis. Characterization of monoclonal antibodies against human adenovirus 41 (h-41) identified an epitope of interest on protein VI, an internal virion protein. The epitope is common to enteric adenoviruses (subgenus A: h-12, h-18, h-31 and subgenus F: h-40, h-41) but is not shared by non-enteric serotypes (subgenera B, C, D or E). By expressing random oligonucleotide fragments of the protein VI gene as T7 gene 10 fusion proteins in the pTope vector (Novagen), the epitope was mapped within the central domain of protein VI, to the region corresponding to aa 114-125 of the Ad2 protein. Identification of this epitope reflects the close evolutionary relationship of subgenus A and subgenus F adenoviruses and draws attention to structural features of enteric adenoviruses as potential determinants of tropism. Furthermore, this epitope may be valuable for identification of enteric adenoviruses in clinical specimens.

Aerosol-mediated delivery of recombinant adenovirus to the airways of nonhuman primates

At present, it is conceivable that gene therapy of the cystic fibrosis airway epithelium is possible using the direct transfer of a functional human cystic fibrosis transmembrane conductance regulator (CFTR) gene to a wide variety of patients' tracheo-bronchial cells. Here we describe a novel approach (aerosolization) to deliver a replication-deficient adenovirus carrying the CFTR gene (Ad.CFTR) to the airways. Results obtained in vitro and in Rhesus monkeys suggest that the delivery of recombinant adenovirus as an aerosol is feasible and is not associated with severe toxicity after single or double administration depending on the Ad.CFTR dose. This study supports the concept of aerosolization as a delivery method for adenovirus-mediated lung gene therapy.

Isolation of epidemic poliovirus from sewage during the 1992-3 type 3 outbreak in The Netherlands

To examine the extent of wild poliovirus circulation during the 1992-3 epidemic in the Netherlands caused by poliovirus type 3, 269 samples from sewage pipelines at 120 locations were examined for the presence of poliovirus. The epidemic virus strain was found in 23 samples, all from locations inside the risk area which contained communities that refuse vaccination for religious reasons. By sewage investigation, the wildtype virus was shown to be present in the early phase of the epidemic at two locations, one week before patients were reported from that area. The wild type 3 poliovirus was also detected retrospectively in a river water sample collected for other reasons three weeks before notification of the first poliomyelitis case, at a site a few kilometres upstream the home village of this patient. Oral poliovirus vaccine (OPV) virus was found at 28 locations inside or at the border of the risk area. Trivalent OPV was offered to unvaccinated or incompletely-vaccinated persons living in this region as part of the measures to control the epidemic.

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.

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.