Identification of subgenus C adenoviruses by fiber-based multiplex PCR

Molecular and epidemiological characterization of human adenovirus and classic human astrovirus in children with acute diarrhea in Shanghai, 2017-2018

BACKGROUND

In addition to rotavirus and norovirus, human adenovirus (HAdV) and classic human astrovirus (classic HAstV) are important pathogens of acute diarrhea in infants and young children. Here, we present the molecular epidemiology of HAdV and classic HAstV in children with acute diarrhea in Shanghai.

METHODS

Fecal specimens were collected from 804 outpatient infants and young children diagnosed with acute diarrhea in Shanghai from January 2017 to December 2018. All of the samples were screened for the presence of HAdV and classic HAstV. HAdV and classic HAstV were detected using traditional PCR and reverse-transcription PCR, respectively. All of the HAdV and classic HAstV positive samples were genotyped by phylogenetic analysis.

RESULTS

Among the 804 fecal samples, 8.58% (69/804) of samples were infected with either HAdV or classic HAstV, and five were co-infected with two diarrhea viruses. The overall detection rates of HAdV and classic HAstV were 3.47% (28/804) and 5.22% (42/804), respectively. Four subgroups (A, B, C, and F) and seven genotypes (HAdV-C1, -C2, -B3, -C5, -A31, -F40, and -F41) of HAdV were detected. Subgroup F had the highest constituent ratio at 64.29% (18/28), followed by non-enteric HAdV of subgroup C (21.43%, 6/28) and subgroup B 10.71% (3/28). HAdV-F41 (60.71%, 17/28) was the dominant genotype, followed by HAdV-C2 (14.29%, 4/28) and HAdV-B3 (10.71%, 3/28). Two genotypes of classic HAstV (HAstV-1 and HAstV-5) were identified in 42 samples during the study period; HAstV-1 (95.24%, 40/42) was the predominant genotype, and the other two strains were genotyped as HAstV-5. No significant differences were found between boys and girls in the detection rates of HAdV (P = 0.604) and classic HAstV (P = 0.275). Over half of the HAdV infections (82.14%, 23/28) and classic HAstV infections (66.67%, 28/42) occurred in children less than 36 months. Seasonal preferences of HAdV and classic HAstV infections were summer and winter, respectively. In this study, the common clinical symptoms of children with acute diarrhea were diarrhea, vomiting, fever and abdominal pain.

CONCLUSIONS

Our findings indicate that HAdV and classic HAstV play important roles in the pathogenesis of acute diarrhea in children in Shanghai. Systematic and long-term surveillance of HAdV and classic HAstV are needed to monitor their prevalence in children and prevent major outbreak.

Adenovirus Isolated From a Cat Is Related to Human Adenovirus 1

An adenovirus (AdV) has been isolated from the rectal swab of a domestic cat (Felis catus) and named feline adenovirus (FeAdV) isolate. It replicates and causes cytopathological effects in many human, feline, other mammalian cell lines that have both Coxsackie-adenovirus-receptor and integrins. Its antigens cross-react with anti-human adenovirus antibodies in immunofluorescence and immunocytochemistry assays. Electron microscopy revealed typical extracellular icosahedral particles and pseudo arrays inside cells. Sequence analysis of hexon and fiber genes indicates that this virus might belong to human adenovirus (HAdV) C species and might be a variant of type 1. In the fiber protein, three altered amino acids occur in the shaft; four altered residues are found in the knob region as compared to a European HAdV might be type 1 isolate (strain 1038, D11). One alteration affects amino acid 442 forming an RGS motif in an alanine rich region that might be an alternative way to bind integrins with subsequent internalization. Substitutions in the hexon sequence are silent. As compared to published HAdV sequences, the fiber is related to the original American prototype and recently described Taiwanese HAdV 1 isolates, but the hexon sequences are related to adenovirus isolates from France, Germany, Japan, and Taiwan. Serology carried out on FeAdV infected M426 cells indicates a prevalence of IgG in 80% of domestic cats in Delaware, United States. FeAdV isolate seems to be a recently recognized virus with possible pathogenic effects and, simultaneous human and feline infections are possible. Further molecular and biological characterization of this feline adenovirus isolate, as well as studies on both human and feline epidemiology and pathomechanisms, especially in endangered big cats, are warranted. FeAdV might have further practical advantages. Namely, it could be utilized in both human and feline AIDS research, developed into diagnostic tools, and gene therapy vectors in the near future.

A multigene typing system for human adenoviruses reveals a new genotype in a collection of Swedish clinical isolates

Human adenoviruses (HAdVs) are common pathogens that can cause respiratory, gastrointestinal, urogenital, and ocular infections. They are divided into seven species containing 85 genotypes. Straightforward typing systems might help epidemiological investigations. As homologous recombination frequently shapes the evolution of HAdVs, information on a single gene is seldom sufficient to allow accurate and precise typing, and complete genome-based methods are recommended. Even so, complete genome analyses are not always easy to perform for practical reasons, and in such cases a multigene system can provide considerably more information about the strain under investigation than single-gene-based methods. Here we present a rapid, generic, multigene typing system for HAdVs based on three main deterministic regions of these viruses. Three PCR systems were used to amplify the genes encoding the DNA polymerase, the penton base hypervariable Arg-Gly-Asp-containing loop, and the hexon loop 1 (hypervariable region 1-6). Using this system, we typed 281 clinical isolates, detected members of six out of seven HAdV species (Human mastadenovirus A-F), and could also detect not only divergent strains of established types but also a new recombinant strain with a previously unpublished combination of adenovirus genomes. This strain was accepted by the Human Adenovirus Working Group as a novel genotype: HAdV-86. Seven strains that could not be typed with sufficient accuracy were also investigated using a PCR based on part of the fiber gene. By analysis of corresponding sequences of the 86 known HAdV genotypes, we determined that the proposed typing system should be able to distinguish all non-recombinant types, and with additional fiber information, all known HAdV genotypes.

Species differences in circulation and inflammatory responses in children with common respiratory adenovirus infections

Human adenoviruses (HAdVs) cause severe inflammatory respiratory infections, but previous epidemiological studies lacked analysis of the characteristics of the inflammation. Consecutive patients <13 years old with acute febrile illness during a 2‐year period were tested. HAdV strains were isolated from nasopharyngeal swabs, and molecular identification was performed by hexon, fiber, and species‐specific PCR methods. Blood inflammatory markers, including the white blood cell (WBC) count, CRP, and 29 cytokines, were measured. A total of 187 patients were enrolled, and HAdV types were identified from 175 patients (93.5%). Species C (types 2, 1, 5, and 6, in order of frequency) was most common at 37.1%, followed by B (type 3) at 30.9% and E (type 4) at 26.9%. Species C was detected predominantly in 1‐year‐old, whereas B and E were in older ages. Species C and B had seasonal circulation patterns, but E was found in only one season during the 2‐year study period. The WBC count was highest in patients with species C. Eleven of the 29 tested serum cytokines were detected. Seven kinds, including G‐CSF, IL‐6, and TNF‐α, were elevated in species C infections, whereas IL‐10 was lowest in species C. Species differences in inflammatory responses, especially regarding serum cytokines were described in common pediatric HAdV infections. Species C causes the strongest inflammatory responses in young children.

Quantitative PCR Detection and Characterisation of Human Adenovirus, Rotavirus and Hepatitis A Virus in Discharged Effluents of Two Wastewater Treatment Facilities in the Eastern Cape, South Africa

The occurrence of enteric viruses in reclaimed wastewater, their removal by efficient treatment processes and the public health hazards associated with their release into the environments are of great significance in environmental microbiology. In this study, TaqMan-based real-time polymerase chain reaction (qPCR) was used to assess the prevalence of human adenovirus (HAdV), rotavirus (RV) and hepatitis A virus (HAV) in the final effluents of two wastewater treatment plants in the Eastern Cape Province, South Africa, over a twelve-month sampling period. The correlation between the concentrations of viruses in the effluents samples and faecal coliform (FC) densities were assessed as to validate the use of FC as microbiological indicator in water quality assessment. HAdV was detected in 62.5 % (30/48) of the samples with concentrations ranging between 8.4 × 101 and 1.0 × 105 genome copies/L while HAV and RV were only detected at concentrations below the set detection limits. FCs densities ranged from 1 to 2.7 × 104 CFU/100 ml. Adenovirus species HAdV-B (serotype 2) and HAdV-F (serotype 41) were detected in 86.7 % (26/30) and 6.7 % (2/30) of the HAdV-positive samples, respectively. No consistent seasonal trend was observed in HAdV concentrations, however, increased concentrations of HAdV were generally observed in the winter months. Also, there was no correlation between the occurrence of HAdV and FC at both the treatment plants. The persistent occurrence of HAdV in the discharged treated effluents points to the potential public health risk through the release of HAdV into the receiving watersheds, and the possibility of their transmission to human population.

Identification of different respiratory viruses, after a cell culture step, by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)

In this study matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS), a reliable identification method for the diagnosis of bacterial and fungal infections, is presented as an innovative tool to investigate the protein profile of cell cultures infected by the most common viruses causing respiratory tract infections in humans. MALDI-TOF MS was applied to the identification of influenza A and B viruses, adenovirus C species, parainfluenza virus types 1, 2 and 3, respiratory syncytial virus, echovirus, cytomegalovirus and metapneumovirus. In this study MALDI-TOF MS was proposed as a model to be applied to the identification of cultivable respiratory viruses using cell culture as a viral proteins enrichment method to the proteome profiling of virus infected and uninfected cell cultures. The reference virus strains and 58 viruses identified from respiratory samples of subjects with respiratory diseases positive for one of the above mentioned viral agents by cell culture were used for the in vitro infection of suitable cell cultures. The isolated viral particles, concentrated by ultracentrifugation, were used for subsequent protein extraction and their spectra profiles were generated by MALDI-TOF MS analysis. The newly created library allowed us to discriminate between uninfected and respiratory virus infected cell cultures.

Adenovirus: Epidemiology, Global Spread of Novel Serotypes, and Advances in Treatment and Prevention

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe and dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue tropisms that correlate with clinical manifestations of infection. The predominant serotypes circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been conducted. Cidofovir is the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States, but currently are not available to civilians.

Quantitative real-time PCR assays for detection and type-specific identification of the endemic species C human adenoviruses

Human adenoviruses (HAdVs) are medically important respiratory pathogens. Among the 7 recognized species (A-G), species C HAdVs (serotypes 1, 2, 5 and 6) are globally endemic and infect most people early in life. Species C HAdV infections are most often subclinical or mild and can lead to persistent shedding from the gastrointestinal and upper respiratory tracts. They can also cause severe disseminated disease in newborn and immunocompromised persons, where rapid and quantitative detection and identification of the virus would help guide therapeutic intervention. To this end, we developed quantitative type-specific real-time PCR (qPCR) assays for HAdV-1, -2, -5 and -6 targeting the HAdV hexon gene. All type-specific qPCR assays reproducibly detected as few as 5 copies/reaction of quantified hexon recombinant plasmids with a linear dynamic range of 8 log units (5-5×10⁷ copies). No non-specific amplifications were observed with concentrated nucleic acid from other HAdV types or other common respiratory pathogens. Of 199 previously typed HAdV field isolates and positive clinical specimens, all were detected and correctly identified to type by the qPCR assays; 10 samples had 2 HAdV types and 1 sample had 3 types identified which were confirmed by amplicon sequencing. The species C HAdV qPCR assays permit rapid, sensitive, specific and quantitative detection and identification of four recognized endemic HAdVs. Together with our previously developed qPCR assays for the epidemic respiratory HAdVs, these assays provide a convenient alternative to classical typing methods.

Molecular identification of adenoviruses associated with respiratory infection in Egypt from 2003 to 2010

Background

Human adenoviruses of species B, C, and E (HAdV-B, –C, -E) are frequent causative agents of acute respiratory infections worldwide. As part of a surveillance program aimed at identifying the etiology of influenza-like illness (ILI) in Egypt, we characterized 105 adenovirus isolates from clinical samples collected between 2003 and 2010.

Methods

Identification of the isolates as HAdV was accomplished by an immunofluorescence assay (IFA) and confirmed by a set of species and type specific polymerase chain reactions (PCR).

Results

Of the 105 isolates, 42% were identified as belonging to HAdV-B, 60% as HAdV–C, and 1% as HAdV-E. We identified a total of six co-infections by PCR, of which five were HAdV-B/HAdV-C co-infections, and one was a co-infection of two HAdV-C types: HAdV-5/HAdV-6. Molecular typing by PCR enabled the identification of eight genotypes of human adenoviruses; HAdV-3 (n = 22), HAdV-7 (n = 14), HAdV-11 (n = 8), HAdV-1 (n = 22), HAdV-2 (20), HAdV-5 (n = 15), HAdV-6 (n = 3) and HAdV-4 (n = 1). The most abundant species in the characterized collection of isolates was HAdV-C, which is concordant with existing data for worldwide epidemiology of HAdV respiratory infections.

Conclusions

We identified three species, HAdV-B, -C and -E, among patients with ILI over the course of 7 years in Egypt, with at least eight diverse types circulating.

Quantitative detection and characterization of human adenoviruses in the Buffalo River in the Eastern Cape Province of South Africa

Buffalo River is an important water resource in the Eastern Cape Province of South Africa. Over a 1-year period (August 2010-July 2011), we assessed the prevalence of human adenoviruses (HAdVs) at a total of 6 sites on the river and three dams along its course. HAdVs were detected by real-time quantitative PCR in about 35 % of the samples with concentrations ranging from 1.2 × 10(1) genome copies (GC)/l to 4.71 × 10(3) GC/l. HAdVs were detected at 5 of the 6 sampling sites with the detection rate ranging from 8.3 % at Rooikrantz Dam to 92 % at Parkside. The HAdV concentrations across the sampling sites were as follows: Parkside (3.25 × 10(2)-4.71 × 10(3) GC/); King William's Town (1.02 × 10(2)-4.56 × 10(3) GC/l); and Eluxolzweni (1.17 × 10(2)-3.97 × 10(2) GC/l). Significantly (P < 0.05) higher concentrations were detected at the non-dam sites compared to the dam sites. A very low mean concentration of 1.86 × 10(1) HAdV GC/l was observed at Bridle Drift Dam. While HAdVs were detected only once at Rooikrantz Dam (1.74 × 10(1) GC/l), no HAdV was detected at Maden Dam. Epidemiologically important serotypes, Ad40/41, constituted 83.3 %, while Ad21 made up 16.7 % of the all HAdVs detected and were characterized by qualitative PCR. The Buffalo River presents a public health risk heightened by the presence of Ad 40/41 and Ad21. Our results make imperative the need for assessing water sources for viral contamination in the interest of public health. This work is a significant contribution to the molecular epidemiology of adenoviruses and to the best of our knowledge this is the first report on detection of enteric virus from surface waters in the Eastern Cape.

Molecular typing of adenoviruses in pediatric respiratory infections in Buenos Aires, Argentina (1999-2010)

BACKGROUND

The human adenovirus (HAdV) types most commonly found in respiratory samples belong to HAdV species C (HAdV-C1, -C2, -C5, and -C6) and to HAdV species B (HAdV-B3 and -B7). Several studies in South America have shown the association between severe respiratory infections and subspecies B1.

OBJECTIVES

The aim of this study was to identify the adenovirus types associated with acute lower respiratory tract infections in children, found as single or coinfections, throughout a 12-year period.

STUDY DESIGN

All samples that tested positive for adenovirus by immunofluorescence assay from January 1999 to December 2010 were typed by evaluating a set of four viral genes (E1A, VA, hexon and fiber). Quantitative PCRs for HAdV-B and HAdV-C species were performed to compare the viral load found in single infections and coinfections.

RESULTS

From a total of 743 HAdV, 654 (88%) were single infections and 89 (12%) coinfections. From the 654 single HAdV infections, members of four species were present: species B (n=492, 75.23%), species C (n=138, 21.1%), species E (n=19, 2.91%), and species D (n=5, 0.76%). Only members of species B (n=109, 57.67%) and species C (n=80, 42.33%) were detected in coinfections. HAdV-B7 and HAdV-B3 were the most prevalent types (n=308, 36.54%; n=230, 27.28% respectively) and HAdV-C1, -C2, -E4, -C5, -C6, -D8, -B11, -B14 and -B21 were also detected. Viral loads for species C viruses were higher in single infections than in coinfections (p<0.01), whereas the opposite was observed for species B viruses (p<0.0001).

CONCLUSIONS

This study provides a thorough description of adenovirus circulation and diversity in Buenos Aires in a 12-year period. The high proportion of coinfections found in this work shows that this phenomenom might be more common than expected.

Detection of adenoviruses

The human adenovirus (hAdV) group is represented by 52 serotypes that have been reported to cause a broad range of clinical manifestations including respiratory tract infections, acute conjunctivitis, cystitis, gastroenteritis, and systemic infections. Conventional methods for detection of hAdVs include electron microscopy, antigen detection, and virus isolation in cell culture. Implementation of real-time PCR assays has increased the sensitivity and speed of detection, and allowed for rapid quantification and serotyping. This chapter describes the design and validation of a multiplex real-time PCR assay for the detection of a broad range of hAdV serotypes in respiratory samples, blood, or urine. This assay targets the conserved region of the hAdV hexon gene and utilizes hydrolysis probes for the detection of amplified products. The assay can be adapted to provide quantitative results to evaluate the change in viral load, and products can be sequenced for serotype designation. PCR-based methods for hAdV detection are sensitive, specific, allow for rapid diagnosis, and facilitate epidemiological studies.

Multiplexed Luminex xMAP assay for detection and identification of five adenovirus serotypes associated with epidemics of respiratory disease in adults

Several serotypes of human adenovirus (HAdV) cause acute respiratory disease (ARD) among healthy adults, sometimes generating broad outbreaks with high attack rates and occasional fatalities. Timely serotype identification provides valuable epidemiological information and significantly contributes to prevention (vaccination) strategies. The prevalence of specific serotypes causing ARD varies geographically. HAdV-3, HAdV-4, HAdV-7, HAdV-14, and HAdV-21 are the serotypes most commonly found in adult populations in the Western Hemisphere. Unfortunately, conventional serotype identification is a tedious process which can take a week or longer. For this reason, new molecular methods for serotype identification are needed. Commercially available rapid antigen and PCR assays for the detection of HAdV are universal but do not distinguish between the different serotypes. We describe the development of a sensitive and specific multiplex assay capable of identifying serotypes 3, 4, 7, 14, and 21. Two sets of primers were used for nonspecific (universal) PCR amplification, and serotype-specific probes coupled to Luminex tags were used for target-specific extension (TSE). PCR and TSE primers were designed using known hexon gene sequences of HAdV. The TSE products of HAdV-3, HAdV-4, HAdV-7, HAdV-14, and HAdV-21 were correctly identified using the Luminex xMAP fluid microsphere-based array system. No cross-reactivity with other respiratory pathogens or other HAdV serotypes was observed. This multiplexed assay can be expanded to include more serotypes and will allow broad and rapid detection and identification of adenoviral serotypes in a high-throughput environment.

[Application of molecular methods in the diagnosis and epidemiological study of viral respiratory infections]

Hasta la fecha se han identificado más de 200 virus pertenecientes a 6 familias taxonómicas diferentes asociados con la infección del tracto respiratorio humano. La utilización generalizada de métodos moleculares en los laboratorios de microbiología clínica no sólo ha aportado grandes ventajas al diagnóstico de estas infecciones, sino también está permitiendo profundizar en el conocimiento de la enfermedad y el comportamiento epidemiológico de los virus causantes. Esta tecnología incrementa de manera notable el rendimiento de detección de virus en las muestras respiratorias, debido a su elevada sensibilidad en comparación con las técnicas clásicas y a la posibilidad de identificar virus no cultivables o de crecimiento fastidioso en las líneas celulares habituales, lo que permite realizar el diagnóstico etiológico con mayor rapidez. Sin embargo, también comporta algunos inconvenientes, como son detectar virus que se encuentran colonizando la mucosa respiratoria de personas asintomáticas, o en secreciones de pacientes que ya se han recuperado de una infección pasada, a consecuencia de excreción prolongada de éstos. La secuenciación de los productos obtenidos en la reacción de amplificación genómica permite caracterizar de forma adicional los virus detectados mediante su genotipado, realizar estudios de epidemiología molecular e identificar resistencias a determinados antivirales, por citar sólo algunos ejemplos.

Detection of a broad range of human adenoviruses in respiratory tract samples using a sensitive multiplex real-time PCR assay

Human adenoviruses (hAdVs) are associated with acute respiratory tract infections in pediatric populations and have been identified as a cause of outbreaks in institutional settings. Rapid diagnosis of hAdV infection is critical for appropriate and timely management. This study reports the design and validation of a sensitive and specific multiplex real‐time PCR for the detection of a broad range of hAdV serotypes in respiratory samples. The assay targets the conserved region of the hAdV hexon gene and utilizes hydrolysis probes for the detection of amplified products. The assay was evaluated using retrospectively (n = 864) and prospectively (n = 11,451) collected samples from November 2005 to July 2006. Seasonality studies and analysis of outbreaks was conducted over a 2‐year period from January 2005 to December 2006 (n = 33,067 samples). The assay gave a hAdV positive rate of 7.1% (n = 811) for specimens tested prospectively and was able to detect a broad range of hAdV serotypes with good sensitivity and specificity. A high rate of co‐infection was noted (21.7%). Adenovirus infections were more prevalent in the young with a median age of 24 months for positive patients. Sequence analysis of hAdV positives showed that serotype 7 was the most prevalent followed by serotypes 2 and 3. Association of hAdVs with respiratory outbreaks was low at 2.3% (6 of 266 outbreaks tested) and no seasonal variation was observed for hAdV infections during the 2‐year study period. This assay can improve the detection of hAdVs in respiratory samples and can be used to provide valuable epidemiological information. J. Med. Virol. 80:856–865, 2008. © 2008 Wiley‐Liss, Inc.

A double-blind, placebo-controlled study of the safety and immunogenicity of live, oral type 4 and type 7 adenovirus vaccines in adults

Adenovirus serotypes 4 (ADV-4) and 7 (ADV-7) are important causes of febrile acute respiratory disease (ARD) in US military recruits. Previously licensed vaccines, which effectively controlled adenovirus-associated ARD, are no longer available. In the Fall of 2004 we conducted this Phase 1 randomized, double-blind, placebo-controlled trial of the live, oral ADV-4 and ADV-7 vaccines made by a new manufacturer to assess their safety and immunogenicity. The adenovirus vaccines were administered orally together in a single dose to thirty subjects. Twenty eight additional subjects received placebo. Subjects were then observed for 8 weeks. The most commonly reported adverse events were nasal congestion (33%), cough (33%), sore throat (27%), headache (20%), abdominal pain (17%), arthralgia (13%), nausea (13%) and diarrhea (13%). None of these rates differed significantly from placebo. The duration of vaccine virus fecal shedding was 7-21 days. Seventy three percent of vaccine recipients seroconverted to ADV-4 (GMT 23.3) while 63% seroconverted to ADV-7 (GMT 51.1) by Day 28. The new ADV-4 and ADV-7 vaccines were safe and induced a good immune response in the study population. Expanded trials for safety and efficacy are in progress.

Isolation and identification of adenovirus from conjunctival scrapings over a two-year period (between 2001 and 2003) in Yokohama, Japan

Over a 2-year period between 2001 and 2003, a total of 115 conjunctival scrapings were collected from patients with keratoconjuctivitis from several hospitals in Yokohama, Japan. Out of 115, 94 (82.4%) cases of adenoviruses were detected by polymerase chain reaction (PCR); 60 (52.1%) by cell culture isolation; and 16 (14.0%) by enzyme-linked immunosorbent assay (ELISA). The serotypes were determined by PCR- restriction fragment length polymorphism analysis (PCR-RFLP) and by the neutralization test (NT). PCR-RFLP was performed using a combination of endonucleases such as HhaI, AluI, and HaeIII. Of the 94 PCR-positive samples, the serotypes of 91 (96.8%) were identified by PCR-RFLP analysis (adenovirus 3: 50%, 4: 11%, and 8: 32%). Out of the 115 samples, 60 samples were identified by the neutralization (adenovirus 3, 4, 7, and 8). When both PCR-RFLP and the neutralization techniques were used, 53.2%, 11.7%, 1.1%, and 34% of the samples were identified as adenovirus 3, 4, 7, and 8, respectively. In contrast to the results of a nationwide surveillance report, adenovirus 3 was found as a major cause of keratoconjunctivitis in the Yokohama area. The nationwide surveillance report did not reflect accurately the epidemiological situation in the local area. In order to obtain surveillance data that would be useful for the prevention of an adenovirus conjunctivitis epidemic, it seems that local epidemiology is more important than that nationwide surveillance.

Co-infections of adenovirus species in previously vaccinated patients

Adenoviral infections associated with respiratory illness in military trainees involve multiple co-infecting species and serotypes.

Despite the success of the adenovirus vaccine administered to US military trainees, acute respiratory disease (ARD) surveillance still detected breakthrough infections (respiratory illnesses associated with the adenovirus serotypes specifically targeted by the vaccine). To explore the role of adenoviral co-infection (simultaneous infection by multiple pathogenic adenovirus species) in breakthrough disease, we examined specimens from patients with ARD by using 3 methods to detect multiple adenoviral species: a DNA microarray, a polymerase chain reaction­ (PCR)–enzyme-linked immunosorbent assay, and a multiplex PCR assay. Analysis of 52 samples (21 vaccinated, 31 unvaccinated) collected from 1996 to 2000 showed that all vaccinated samples had co-infections. Most of these co-infections were community-acquired serotypes of species B1 and E. Unvaccinated samples primarily contained only 1 species (species E) associated with adult respiratory illness. This study highlights the rarely reported phenomenon of adenoviral co-infections in a clinically relevant environment suitable for the generation of new recombinational variants.

PCR analysis of egyptian respiratory adenovirus isolates, including identification of species, serotypes, and coinfections

Eighty-eight adenovirus (Ad) isolates and associated clinical data were collected from walk-in patients with influenza-like illness in Egypt during routine influenza surveillance from 1999 through 2002. Respiratory Ad distributions are geographically variable, and serotype prevalence has not been previously characterized in this region. Serotype identity is clinically relevant because it predicts vaccine efficacy and correlates strongly with both clinical presentation and epidemiological pattern. Species and serotype identities were determined using several well-validated multiplex PCR protocols culled from the literature and supplemented with a few novel primer sets designed to identify rare types. The isolates included common species B1 serotypes (Ad3 and Ad7), common species C serotypes (Ad1, Ad2, and Ad5), the less common species B2 serotype Ad11, and three isolates of the rare species B1 serotype Ad16. Two isolates that appear to be variant Ad16 were also identified. Fifteen coinfections of multiple adenoviral types, primarily AdB/AdC and Ad3/Ad7 dual infections, were detected. The majority of these were verified using redundant PCR tests targeted at multiple genes. PCR is able to resolve coinfections, in contrast to traditional serum neutralization tests. PCR is also comparatively rapid and requires very little equipment. Application of the method allowed an inclusive determination of the serotypes found in the Egyptian respiratory sample set and demonstrated that coinfections are common and may play a previously unrecognized role in adenovirus pathogenesis, evolution, and epidemiology. In particular, coinfections may influence adenoviral evolution, as interserotypic recombination has been identified as a source of emerging strains.

Multiplex PCR assay for rapid identification of oculopathogenic adenoviruses by amplification of the fiber and hexon genes

Eye infections caused by adenovirus (Ad) often result in nosocomial infections and community epidemics with significant rates of morbidity. No antiviral agent effective against Ad is yet available for clinical use. Therefore, early diagnosis is still the mainstay for patient management and the prevention of epidemics. A multiplex PCR assay based on amplification of a combination of the fiber and hexon genes which can identify the six important oculopathogenic serotypes of Ads (Ad serotype 3[Ad3], Ad4, Ad7, Ad8, Ad19, and Ad37) in a single-tube amplification reaction was developed. Ad serotypes could be distinguished by the different amplicon sizes. The assay correctly identified prototype strains as well as isolates in clinical specimens. In comparison with a previously described PCR-restriction fragment polymorphism method, our assay gave unequivocal results for clinical specimens. Our multiplex PCR has the potential to serve as a rapid and cost-effective tool for the typing of important ocular Ads.

A review of viral gastroenteritis

PURPOSE OF REVIEW

Since Kapakian first identified a virus in the stool of a patient with diarrhoea in 1972, many viruses have been described that cause diarrhoea directly or indirectly. It is now appreciated that viruses are the most common cause of diarrhoeal illness worldwide. Although bacteria and other pathogens cause significant numbers of gastroenteritis, it is the viruses that are dealt with in this review. The viruses responsible will be discussed individually.

RECENT FINDINGS

Rotavirus remains the leading cause of diarrhoeal disease overall, with the newly designated calicivirus family causing the most outbreaks in the industrialized nations. As diagnostic techniques improve, however, the importance of astrovirus and other previously under-reported pathogens is becoming more apparent and the number of viruses associated with gastroenteritis continues to increase. The emergence of severe acute respiratory syndrome coronavirus, arguably the most important emerging infection of recent years and a cause of significant gastrointestinal disease, is also discussed.

SUMMARY

No effective treatments have been developed for viral gastroenteritis. Current efforts are targeted at the development of suitable vaccines and the implementation of infection control measures.