Worldwide epidemiology of human adenovirus infections

The seroprevalence of adenoviruses since 20001

Human adenoviruses (Ad) are increasingly used as vaccine vectors, especially after Ad5, Ad26, and ChAdY25 (ChAdOx1) were employed as vectors for SARS-CoV-2 vaccines. So far, more than 116 adenovirus genotypes have been identified, divided into 7 species (A-G). Most adenoviruses do not cause diseases or are mildly pathogenic, with only species B and E leading to acute respiratory infections or conjunctival inflammation and species F causing gastrointestinal infections. Previous studies have shown that the seroprevalence of neutralizing antibodies against adenoviruses can be limiting when applying adenoviral vectors. On the other hand, for highly pathogenic adenoviruses, neutralizing antibodies is beneficial for preventing the diseases caused by these adenoviruses. Here, we summarized the studies on the seroprevalence of adenoviruses, especially adenoviruses that may be utilized as vectors for vaccine and gene therapy. We also analysed possible factors associated with the seroprevalence and neutralizing titres. Given the trend of increasing adenoviral vector application, it is necessary to continue the investigation of the seroprevalence of neutralizing antibodies against adenoviruses in different geographic locations and populations.

Microbiological spectrum and antibiotic susceptibility patterns of non-viral conjunctivitis over 16 years at a tertiary eye care center in Southern India

PURPOSE

To determine the trends in the microbial spectrum and antibacterial susceptibility patterns of non-viral conjunctivitis over 16 years.

METHODS

Microbiology data were reviewed from 2006-2021 for all the patients with clinically and culture-proven infectious conjunctivitis. Conjunctival swabs and/or conjunctival scrapings were collected for microbiological workup, and the demographic and antibiotic susceptibility data were extracted from the EMR (Electronic Medical Record). For statistical analysis, χ2-test was performed.

RESULTS

Of the 1711 patients, 814 (47.57%) were culture positive and 897 (52.43%) were culture negative. Of the total culture-proven conjunctivitis cases, 775/814 (95.20%) were bacteria, and 39/814 (4.80%) were fungi. Among these bacterial isolates, 75.74% were gram-positive bacteria, while 24.26% were gram negative. The predominant gram-positive pathogens isolated were S. epidermidis (16.7%), S. aureus (17.9%) (p < 0.05), and S. pneumoniae (18.2%), while Haemophilus spp. (36.2%) (p < 0.05) was the most often isolated gram-negative bacteria (36.2%), and Aspergillus spp. was the most commonly isolated fungus (50%). The susceptibility of gram-positive bacteria to cefazoline increased from 90.46 to 98% (p = 0.01), whereas the susceptibility for gatifloxacin decreased in both gram-positive (81-41%; p < 0.0001) and gram-negative bacteria (73-58%; p = 0.02).

CONCLUSIONS

Increasing resistance of ocular isolates to mainstay antibiotics is a concern, and this data can assist healthcare practitioners in making informed choices regarding the treatment of ocular infections with ophthalmic antibiotics.

Epidemiology of Human Adenovirus in Pakistani Children Hospitalized with Community-Acquired Gastroenteritis under the Age of Five Years

Acute gastroenteritis is the major cause of morbidity and mortality among infants and children around the globe. Along with other enteropathogens, human adenovirus (HadV) is a major etiological agent associated with diarrhea in young children. However, information about the epidemiology of Adenoviruses in Pakistan is limited or has not been reported. A total of 1082 stool samples were collected from patients with acute gastroenteritis under the age of five years with symptoms of diarrhea, vomiting, nausea, and abdominal cramps who visited Benazir Bhutto Hospital Rawalpindi and Children's hospital in Lahore of Punjab Province in Pakistan. Of this, 384 cases with no blood in their stool, negative for Rotavirus, and under the age of five years were recruited in this study. Human Adenoviruses were isolated in the human epithelial HEp-2 cell line. Furthermore, adenovirus antigen detection was carried out by an enzyme-linked immunosorbent assay (ELISA), and then all positive and negative samples were confirmed by nested PCR. After inoculating a clear stool supernatant on HEp-2 cell lines, we observed a positive cytopathic effect in 65 (16%) cases. Using an enzyme-linked immunosorbent assay, HAdV antigens were detected in 54 (14.06%) of the clear supernatant from gastroenteritis cases. However, HAdV hexon coding regions were amplified in 57 (14.80%) fecal samples, mainly from patients ≤24 months of age. The findings of this study suggest that adenovirus circulates significantly in the children population under the age of five years and may be the potential etiological factor of acute gastroenteritis in the mentioned cities. This study provides baseline data about the possible role of adenovirus in causing viral diarrhea in children. Further large-scale epidemiological surveys are recommended to better understand disease burden, etiological agents, and its clinical impact across the country.

High genetic stability of co-circulating human adenovirus type 31 lineages over 59 years

Type 31 of human adenovirus species A (HAdV-A31) is a significant pathogen primarily associated with diarrhoea in children but also with life-threatening disseminated disease in allogeneic haematopoietic stem cell transplant (HSCT) recipients. Nosocomial outbreaks of HAdV-A31 have been frequently described. However, the evolution of HAdV-A31 has not been studied in detail. The evolution of other HAdV types is driven either by intertypic recombination, where different types exchange genome regions, or by immune escape selection of neutralisation determinants. Complete genomic HAdV-A31 sequences from sixty diagnostic specimens of the past 18 years (2003-21) were generated, including fourteen specimens of a presumed outbreak on two HSCT wards. Additionally, twenty-three complete genomes from GenBank were added to our phylogenetic analysis as well as in silico generated and previously published restriction fragment polymorphism (RFLP) data. Phylogenetic analysis of eighty-three genomes indicated that HAdV-A31 evolved slowly with six lineages co-circulating. The two major lineages were lineage 1, which included the prototype from 1962 and nine recent isolates, and lineage 2, which split into four sublineages and included most isolates from 2003 to 2021. The average nucleotide identity within lineages was high (99.8 per cent) and identity between lineages was 98.7 and 99.2 per cent. RFLP data allowed the construction of a lower-resolution phylogeny with two additional putative lineages. Surprisingly, regions of higher diversity separating lineages were found in gene regions coding for non-structural and minor capsid proteins. Intertypic recombinations were not observed, but the phylogeny of lineage 3 was compatible with an interlineage recombination event in the fibre gene. Applying the phylogenetic analysis to the presumed nosocomial outbreak excluded two suspected transmission events and separated it into two different, simultaneous outbreaks caused by different sublineages of lineage 2. However, due to the high nucleotide identity within HAdV-A31 lineages, the proof of infection chains remains debatable. This in-depth study on the molecular phylogeny of HAdV-A31 highlights the high genetic stability of co-circulating HAdV-A31 lineages over almost six decades. It also supports the epidemiological hypothesis that HAdV-A31 circulates as an etiological agent of a childhood disease infecting immunologically naive patients without strong positive selection of immune escape variants and recombinants.

Seroprevalence of neutralizing antibodies against adenovirus type 26 and 35 in healthy populations from Guangdong and Shandong provinces, China

Human adenoviruses type 26 (HAdV26) and type 35 (HAdV35) have increasingly become the choice of adenovirus vectors for vaccine application. However, the population pre-existing immunity to these two adenoviruses in China, which may reduce vaccine efficacy, remains largely unknown. Here, we established micro-neutralizing (MN) assays to investigate the seroprevalence of neutralizing antibodies (nAbs) against HAdV26 and HAdV35 in the general population of Guangdong and Shandong provinces, China. A total of 1184 serum samples were collected, 47.0% and 15.8% of which showed HAdV26 and HAdV35 nAb activity, respectively. HAdV26-seropositive individuals tended to have more moderate nAbs titers (201–1000), while HAdV35-seropositive individuals appeared to have more low nAbs titers (72–200). The seropositive rates of HAdV26 and HAdV35 in individuals younger than 20 years old were very low. The seropositive rates of HAdV26 increased with age before 70 years old and decreased thereafter, while HAdV35 seropositive rates did not show similar characteristics. Notably, the seropositive rates and nAb levels of both HAdV26 and HAdV35 were higher in Guangdong Province than in Shandong Province, but did not exert significant differences between males and females. The seroprevalence between HAdV26 and HAdV35 showed little correlation, and no significant cross-neutralizing activity was detected. These results clarified the characteristics of the herd immunity against HAdV26 and HAdV35, and provided information for the rational development and application of HAdV26 and HAdV35 as vaccine vectors in China.

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We address the pre-existing immunity of HAdV26 and HAdV35.

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The overall seroprevalence of nAbs against HAdV26 and HAdV35 were 47.0% and 15.8%.

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The seroprevalence level of HAdV26 and HAdV35 differed in age and in district.

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Pre-existing immunity should be considered when adenoviral vectors are used.

Molecular Typing and Rapid Identification of Human Adenoviruses Associated With Respiratory Diseases Using Universal PCR and Sequencing Primers for the Three Major Capsid Genes: Penton Base, Hexon, and Fiber

Human adenoviruses (HAdVs) within species B, C, and E are responsible for highly contagious and potentially severe respiratory disease infections. The traditional method to type these pathogens was based on virus neutralization and hemagglutination assays, which are both time-consuming and difficult, particularly due to the nonavailability of reagents. Subsequent molecular typing based on the partial characterization of the hexon gene and/or the restriction enzyme analysis (REA) of the genomes is inadequate, particularly in identifying recombinants. Here, a rapid, simple, and cost-effective method for molecular typing HAdV respiratory pathogens is presented. This incorporates three pairs of universal PCR primers that target the variable regions of the three major capsid genes, i.e., hexon, penton base, and fiber genes, that span the genome. The protocol enables typing and characterization of genotypes within species B, C, and E, as well as of some genotypes within species D and F. To validate this method, we surveyed 100 children with HAdV-associated acute respiratory infections identified by direct immunofluorescence (Hong Kong; July through October, 2014). Throat swab specimens were collected and analyzed by PCR amplification and sequencing; these sequences were characterized by BLAST. HAdVs were detected in 98 out of 100 (98%) samples, distributing as follows: 74 HAdV-B3 (74%); 10 HAdV-E4 (10%); 7 HAdV-C2 (7%); 2 HAdV-C6 (2%); 1 HAdV-B7 (1%); 1 HAdV-C1 (1%); 2 co-infection (2%); and 1 novel recombinant (1%). This study is the first detailed molecular epidemiological survey of HAdVs in Hong Kong. The developed method allows for the rapid identification of HAdV respiratory pathogens, including recombinants, and bypasses the need for whole genome sequencing for real-time surveillance of circulating adenovirus strains in outbreaks and populations by clinical virologists, public health officials, and epidemiologists.

Fatal adenovirus pneumonia in a 15-day-old infant despite extracorporeal life support treatment: A case report

Infections are one of the most common causes of severe neonatal diseases and the leading cause of neonatal death. Although respiratory viral infections are widespread, they are still not recognized as the predominant causes of neonatal deaths. Adenovirus infection is uncommon during the neonatal period, and it frequently has a fatal outcome. Furthermore, it is difficult to distinguish from other common bacterial and respiratory viral infections. The present study reports the case of a 15-day-old newborn who presented with coagulation disorders and hypoxemia in September, 2020. Human adenovirus of species D-53 (HAdV-D53) was detected in the blood and sputum. Severe pneumonia rapidly progressed to multiple organ failure syndrome and the patient succumbed to the disease, despite receiving extracorporeal membrane oxygenation.

Serotype Identification of Human Adenoviruses Associated with Influenza-Like Illnesses in the Philippines from 2006-2012 by Microneutralization and Molecular Techniques

OBJECTIVES

Human adenoviruses (HAdV) are known to cause a wide range of diseases including acute respiratory infections, conjunctivitis, and acute gastroenteritis. In this study, we aimed to determine the serotypes of HAdV in patients with influenza-like illness (ILI) in the Philippines from 2006-2012 and to describe the demographic and epidemiological characteristics of patients who tested positive for HAdV.

METHODS

Between 2006 and 2012, the Philippine National Influenza Centre detected HAdV in 1294 samples of patients with ILI. Serotype determination was done in select samples using microneutralization, polymerase chain reaction (PCR), and sequencing methods.

RESULTS

A total of 8 serotypes were identified (HAdV 1-7 and 11), with HAdV-2 (27.8%), and HAdV-3 (27.8%) being the most prevalent. The majority of HAdV infections were found in children below 5 years of age (79.9%).

CONCLUSIONS

The identification of HAdV circulating serotypes may serve as guide for designing disease intervention and control strategies and will provide important information regarding the contribution of this virus to respiratory infections, particularly in children, which remain a public health burden in the Philippines.

Adenovirus: Epidemiology, Global Spread of Novel Types, and Approach to Treatment

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 vast majority of cases are self-limited. However, the clinical spectrum is broad and fatalities may occur. 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 100 genotypes and 52 serotypes of AdV have been identified and classified into seven species designated HAdV-A through -G. Different types display different tissue tropisms that correlate with clinical manifestations of infection. The predominant types 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 done. Cidofovir has been 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.

Morbidity burden, seasonality and factors associated with the human respiratory syncytial virus, human parainfluenza virus, and human adenovirus infections in Kenya

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Human respiratory syncytial (HRSV), parainfluenza (HPIV) and adenoviruses (HAdV)

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These non-influenza viruses contributed to influenza-like illness morbidity burden

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HRSV, HPIV and HAdV infections had a significant impact on infants

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HRSV had a clear seasonal pattern, with cases peaking around April–May each year

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During the surveillance period, HRSV was associated with climate parameters

Background

Human respiratory syncytial viruses (HRSV), human parainfluenza viruses (HPIV), and human adenoviruses (HAdVs) cause a substantial morbidity burden globally.

Objective

We sought to estimate morbidity burden, assess seasonality, and determine factors associated with these respiratory viruses in Kenya.

Methods

The data were obtained from Kenyan sites included in the Köppen-Geiger climate classification system. We defined the proportion of morbidity burden by descriptive analysis and visualized time-series data for January 2007–December 2013. Logistic regression was used to identify factors associated with infection outcomes.

Results

The morbidity burden for HRSV was 3.1%, HPIV 5.3% and HAdVs 3.3%. Infants were more likely to be infected than other age groups. HRSV exhibited seasonality with high occurrence in January–March (odds ratio[OR] = 2.73) and April–June (OR = 3.01). Hot land surface temperature (≥40 °C) was associated with HRSV infections (OR = 2.75), as was warmer air temperature (19-22.9 °C) (OR = 1.68), compared with land surface temperature (<30) and cooler air temperature (<19 °C) respectively. Moderate rainfall (150-200 mm) areas had greater odds of HRSV infection (OR = 1.32) than low rainfall (<150 mm).

Conclusion

HRSV, HPIV and HAdVs contributed to morbidity burden, and infants were significantly affected. HRSV had a clear seasonal pattern and were associated with climate parameters, unlike HPIV and HAdVs.

Capsid and Genome Modification Strategies to Reduce the Immunogenicity of Adenoviral Vectors

Adenovirus-based gene transfer vectors are the most frequently used vector type in gene therapy clinical trials to date, and they play an important role as genetic vaccine candidates during the ongoing SARS-CoV-2 pandemic. Immediately upon delivery, adenovirus-based vectors exhibit multiple complex vector-host interactions and induce innate and adaptive immune responses. This can severely limit their safety and efficacy, particularly after delivery through the blood stream. In this review article we summarize two strategies to modulate Ad vector-induced immune responses: extensive genomic and chemical capsid modifications. Both strategies have shown beneficial effects in a number of preclinical studies while potential synergistic effects warrant further investigations.

Genetic Analysis of Human Adenovirus Type 7 Strains Circulating in Different Parts of China

To investigate the molecular epidemiology and genetic variation of human adenovirus type 7 (HAdV-7) in children with acute respiratory infections (ARI) in China. HAdV-7-positive respiratory samples collected from children with ARI in Beijing, Shijiazhuang, Wenzhou and Guangzhou from 2014-2018 were selected for gene amplification and sequence analysis. Fifty-seven HAdV-7 clinical strains with hexon, penton base and fiber gene sequences were obtained. Meanwhile 17 strains were selected randomly from different cities for whole genome sequencing. Phylogenetic and variation analyses were performed based on the obtained sequences, HAdV-7 prototype strain Gomen (AY594255), vaccine strains (AY495969 and AY594256) and representative sequences of strains. The phylogenetic trees constructed based on whole genome sequences, major capsid protein genes (hexon, penton base and fiber) and the early genes (E1, E2, E3 and E4) were not completely consistent. The HAdV-7 strains obtained in this study always clustered with most of the circulating strains worldwide from the 1980s to the present. Compared with the HAdV-7 prototype strain Gomen (AY594255), some amino acid mutations in loop1 and loop2 of hexon and the RGD loop region of the penton base gene were observed. Recombination analysis showed that partial regions of 55 kDa protein and 100 kDa hexon-assembly associated protein genes among all HAdV-7 strains in this study were from HAdV-16 and HAdV-3, respectively. Our study demonstrated the molecular evolution characteristics of HAdV-7 strains circulating in China and provided basic reference data for the prevention, control and vaccine development of HAdV-7.

Risk factors for the development of bronchiolitis obliterans in children with severe adenovirus pneumonia: A retrospective study with dose-response analysis

To investigate and analyze the relevant risk factors for bronchiolitis obliterans (BO) in children with severe adenovirus pneumonia, a retrospective study of children with severe adenovirus pneumonia was performed in 34 cases that developing BO and 105 cases not developing BO in Children's hospital of Chongqing Medical University from January 2015 to February 2019. The multivariate logistic regression analysis was used to identify factors which were significantly associated with development of BO after the univariate analysis, and receiver operating characteristic (ROC) curve analysis was performed to find out the cut-off value for the significant relevant factors. A nonlinear dose-response relationship between risk factors and the risk of BO was assessed by restricted cubic spline model. Three factors were independently associated with development of BO, which were length of fever (OR 1.129, 95% CI 1.033-1.234), dyspnea (OR 3.922, 95% CI 1.060-14.514) and invasive mechanical ventilation (OR 6.861, 95% CI 1.854-25.387). The cut-off value of length of fever were 10.5 days. A linear dose-response relationship between length of fever and occurrence of BO was observed (P = .57 for nonlinearity). Children with severe adenovirus pneumonia who have a longer duration of fever (especially more than 10.5 days), have dyspnea or require invasive mechanical ventilation in the acute phase are more likely to develop BO.

Human adenoviruses associated with respiratory illness in neonates, infants, and children in the Sousse area of Tunisia

Background

The human Adenovirus (HAdV) is a common agent of acute respiratory infections (ARIs). Its clinical impact in immunocompetent children and in the context of coinfections remains unclear in Tunisia.

Material and methods

HAdV‐ARIs were studied in hospitalized patients from birth to the age of 5 years from 2013 to 2014. Clinical and demographic characteristics, coinfections, and molecular characterization of HAdV were established.

Results

HAdV‐positivity was detected in 114/583 specimens (19.6%) including 6.1% single infections and 93.9% coinfections. Adenoviral coinfections mostly comprised human Rhinovirus (50.9%), Streptococcus pneumoniae (34.2%), human Respiratory Syncytial virus A/B (29.8%), and human Coronaviruses (21.9%). HAdV infection was predominant in the pediatric population (25.0% vs 10.0% in neonates, P < .001) and peaked in February 2014 (21.1%). HAdV severity of pediatric cases is characterized by low saturation of oxygen (<94%, 33.8%, P = .05) and long duration of oxygen support (≥5 days, 32.7%, P = .02). Severe HAdV infections were described with S. pneumoniae coinfection, which seemed to increase the risk of death. HAdV genotyping identified HAdV‐C as the most common species. Severe ARIs were observed in all HAdV‐identified types. Phylogenetic analysis revealed that sequences were variable suggesting the circulation of different HAdV strains sharing more similarities to strains circulating in Europe or Asia than those from Africa.

Conclusion

This first molecular study of HAdV in Tunisia demonstrated that it has an important role in severe ARIs with HAdV‐C being the most common species. S. pneumoniae codetection seems to increase the severity of HAdV‐ARIs.

A review of 65 years of human adenovirus seroprevalence

Introduction: Human adenovirus (HAdV)-derived vectors have been used in numerous pre-clinical and clinical trials during the last 40 years. Current research in HAdV-based vaccines focuses on improving transgene immunogenicity and safety. Because pre-existing humoral immunity against HAdV types correlate with reduced vaccine efficacy and safety, many groups are exploring the development of HAdV types vectors with lower seroprevalence. However, global seroepidemiological data are incomplete. Areas covered: The goal of this review is to centralize 65 years of research on (primarily) HAdV epidemiology. After briefly addressing adenovirus biology, we chronical HAdV seroprevalence studies and highlight major milestones. Finally, we analyze data from about 50 studies with respect to HAdVs types that are currently used in the clinic, or are in the developmental pipeline. Expert opinion: Vaccination is among the most efficient tools to prevent infectious disease. HAdV-based vaccines have undeniable potential, but optimization is needed and antivector immunity remains a challenge if the same vectors are to be administrated to different populations. Here, we identify gaps in our knowledge and the need for updated worldwide epidemiological data.

Immunoglobulins and virus antibody titers: of past needs, current requirements, and future options

BACKGROUND

Immunoglobulins (Igs) have been in clinical use for almost 70 years, and early on were also used in conjunction with exposure to the measles virus or polio virus. The US regulations that describe functional Ig lot release thus require the demonstration of minimum antibody titers against these two viruses, although the use of vaccines has now dramatically reduced their incidence. The lower clinical importance of these viruses raises the question of whether other virus antibodies might be more informative for patients with immunodeficiency.

STUDY DESIGN AND METHODS

A literature survey was conducted to identify viruses of potential clinical concern for people with immunodeficiency. The viruses selected have stable seroepidemiology and associated functional antibody assays. As a result, neutralizing antibody titers to human adenovirus 5 (HAdV5), respiratory syncytial virus (RSV) serotypes A and B, and human parainfluenza virus 3 (hPIV3) were determined in Ig lots produced from plasma collected in either the United States or the European Union.

RESULTS

The virus antibody titers measured were high and consistent among the Ig lots tested. Use of either US- or EU-derived plasma as starting material resulted in equivalent virus antibody titers, with the exception of RSV serotype B, for which a lower titer was seen in EU plasma-derived Ig lots.

CONCLUSION

With the significant decline in measles virus and polio virus circulation, and even their potential eradication, measurement of antibody titers against other viruses in Ig products may be more informative for functional lot release testing.

Post-infectious bronchiolitis obliterans

Bronchiolitis obliterans is a rare and severe chronic lung disease resulting from a lower respiratory tract lesion. It may occur after a bone marrow or lung transplantation, infectious diseases, or less frequently after inhaling toxic substances or after connective tissue diseases. Pathology, pathogenesis, and molecular biology, as well as the best treatment of bronchiolitis obliterans, remain the subject of ongoing research. This review discusses our current knowledge of different areas of bronchiolitis obliterans associated with infectious lesions.

Adenovirus Type 4 Respiratory Infections among Civilian Adults, Northeastern United States, 2011-20151

Human adenovirus type 4 (HAdV-4) is most commonly isolated in military settings. We conducted detailed molecular characterization on 36 HAdV-4 isolates recovered from civilian adults with acute respiratory disease (ARD) in the northeastern United States during 2011–2015. Specimens came from college students, residents of long-term care facilities or nursing homes, a cancer patient, and young adults without co-morbidities. HAdV-4 genome types 4a1 and 4a2, the variants most frequently detected among US military recruits in basic training before the restoration of vaccination protocols, were isolated in most cases. Two novel a-like variants were recovered from students enrolled at a college in Tompkins County, New York, USA, and a prototype-like variant distinguishable from the vaccine strain was isolated from an 18-year-old woman visiting a physician’s office in Ulster County, New York, USA, with symptoms of influenza-like illness. Our data suggest that HAdV-4 might be an underestimated causative agent of ARD among civilian adults.

Seroepidemiological investigation of HAdV-4 infection among healthy adults in China and in Sierra Leone, West Africa

An apparent increase in the frequency of human adenovirus type 4 (HAdV-4) infections among general populations has been observed over the past 10 years. However, available epidemiological data that may reflect previous viral circulation and assist in predicting potential outbreaks are sparse, particularly in mainland China and Africa. In this study, a convenient neutralization assay for use in the surveillance of historical HAdV-4 infections was established based on a recombinant luciferase-expressing virus. Subsequently, the neutralizing antibodies (nAbs) of 1013 healthy adult serum samples from China and Sierra Leone were evaluated. Our results showed that over 50% of the participants from China and nearly 70% of donors from Sierra Leone had detectable nAbs against HAdV-4 despite the few infection cases officially reported in these regions. Furthermore, the prevalence of nAbs to HAdV-4 is lower than that to HAdV-5, and both varied by geographic location. In addition, the seropositive rates of both HAdV-4 and HAdV-5 nAbs increased with age. However, the nAbs stimulated by HAdV-4 remained stable at low (≤200) levels among the different age groups, whereas moderate (201–1000) or high (>1000) nAb levels were produced by HAdV-5 and tended to decrease with age. These results elucidate the human humoral immune response against HAdV-4 and revealed that this virus may be an underestimated causative agent of respiratory disease among adults in China and West Africa, demonstrating the importance of HAdV-4 surveillance and providing useful insights for the future development of HAdV-4-based vaccines.

Adenovirus Infection of Human Enteroids Reveals Interferon Sensitivity and Preferential Infection of Goblet Cells

Human adenoviruses (HAdV) are significant human pathogens. Although only a subset of HAdV serotypes commonly cause gastroenteritis in humans, most HAdV species replicate in the gastrointestinal tract. Knowledge of the complex interaction between HAdVs and the human intestinal epithelium has been limited by the lack of a suitable cell culture system containing relevant cell types. Recently, this need has been met by the stable and prolonged cultivation of primary intestinal epithelial cells as enteroids. Human enteroids have been used to reveal novel and interesting aspects of rotavirus, norovirus, and enterovirus replication, prompting us to explore their suitability for HAdV culture. We found that both prototype strains and clinical isolates of enteric and nonenteric HAdVs productively replicate in human enteroids. HAdV-5p, a respiratory pathogen, and HAdV-41p, an enteric pathogen, are both sensitive to type I and III interferons in human enteroid monolayers but not A549 cells. Interestingly, HAdV-5p, but not HAdV-41p, preferentially infected goblet cells. And, HAdV-5p but not HAdV-41p was potently neutralized by the enteric human alpha-defensin HD5. These studies highlight new facets of HAdV biology that are uniquely revealed by primary intestinal epithelial cell culture.IMPORTANCE Enteric adenoviruses are a significant cause of childhood gastroenteritis worldwide, yet our understanding of their unique biology is limited. Here we report robust replication of both prototype and clinical isolates of enteric and respiratory human adenoviruses in enteroids, a primary intestinal cell culture system. Recent studies have shown that other fastidious enteric viruses replicate in human enteroids. Therefore, human enteroids may provide a unified platform for culturing enteric viruses, potentially enabling isolation of a greater diversity of viruses from patients. Moreover, both the ability of interferon to restrict respiratory and enteric adenoviruses and a surprising preference of a respiratory serotype for goblet cells demonstrate the power of this culture system to uncover aspects of adenovirus biology that were previously unattainable with standard cell lines.

Worldwide increased prevalence of human adenovirus type 3 (HAdV-3) respiratory infections is well correlated with heterogeneous hypervariable regions (HVRs) of hexon

Human adenovirus type 3 (HAdV-3) respiratory infections occurs worldwide in both children and adults, leading to severe morbidity and mortality, particularly in the paediatric age group and especially in neonates. During HAdV infection, neutralizing antibodies are formed against the epitopes located in the hyper variable regions (HVRs) of the hexon protein. These neutralizing antibodies provide protection against reinfection by viruses of the same type. Therefore it is reasonable to speculate that variations of HAdV-3 in the HVRs could impair the immunity acquired by previous infection with a different strain with variation in its HVRs. HAdV-3 has recently become the major agent of acute respiratory infection worldwide, being responsible for 15% to 87% of all adenoviral respiratory infections. However, despite the increased prevalence of HAdV-3 as respiratory pathogen, the diversity of hexon proteins in circulating strains remains unexplored. This study was designed to explore the variation in HVRs of hexon among globally distributed strains of HAdV-3 as well as to discover possible relationship among them, thus possibly shedding light on the cause for the increased prevalence of HAdV-3. In this study, for the first time we analysed the hexon proteins of all 248 available strains of HAdV-3 from the NCBI database and compared them with those of the HAdV-3 prototype (GB stain). We found that the HVRs of HAdV-3 strains circulating worldwide were highly heterogeneous and have been mutating continuously since -their original isolation. Based on their immense heterogeneity, the strains can be categorized into 25 hexon variants (3Hv-1 to 3Hv-25), 4 of which (3Hv-1 to 3Hv-4) comprises 80% of the strains. This heterogeneity may explain why HAdV-3 has become the most prevalent HAdVs type worldwide. The heterogeneity of hexon proteins also shows that the development of a vaccine against HAdV-3 might be challenging. The data on hexon variants provided here may be useful for the future epidemiological study of HAdV-3 infection.

Hematochezia and thrombocytopenia in a 3-day-old infant: Congenital adenoviral infection

Neonatal adenovirus infection is infrequent, but in most cases the outcome of the infection is fatal. In this case report we describe the hospital course of a 3 day old newborn patient presenting with bloody stools and thrombocytopenia that remained clinically stable and had a benign course following Adenovirus 40/41 infection detected in stool. Neonatal adenovirus infection should be considered in the differential diagnosis of neonatal sepsis and pneumonia but also in patients that present with hematochezia, thrombocytopenia and/or other less specific signs and symptoms of viral illness.

Male Syrian hamsters are more susceptible to intravenous infection with species C human adenoviruses than are females

Recently, increasing attention has been focused on the influence of sex on the course of infectious diseases. Thus far, the best-documented examples point toward an immune-mediated mechanism: the generally stronger immune response in females can result in a faster clearance of the pathogen or, conversely, a more severe immune-mediated pathology. Here, we report that human species C adenoviruses replicate more and cause more pathology in male Syrian hamsters than in females. We also show that this sex disparity is not caused by a stronger immune response to the infection by the female hamsters. Rather, the liver of male hamsters is more susceptible to adenovirus infection: after intravenous injection, more hepatocytes become infected in male animals than in females. We hypothesize that Kupffer cells (hepatic tissue macrophages) of female animals are more active in sequestering circulating virions, and thus protect hepatocytes more efficiently than those of males.

Genomic diversity of human adenovirus type 3 isolated in Fukui, Japan over a 24-year period

Recently, human adenovirus type 3 (HAdV-3) has become the most isolated HAdV worldwide. Restriction endonuclease analysis of globally isolated strains of HAdV-3 has uncovered 51 genome types to date. Information on the genome type is important to the epidemiological study of HAdV-3. In this study, analysis of 75 isolates of HAdV- 3 collected over a 24-year period in Fukui revealed: (1) the emergence of three novel genome types (HAdV-3a52, HAdV-3a53 and HAdV-3a54) and two known genome types (HAdV-3a and HAdV-3a54); (2) the spectrum of diseases caused by individual genome types and their major involvement in the paediatric age population; and (3) the co-circulation and replacement of genome types as a usual phenomenon. The rising number of HAdV-3 genome types indicates that the genetic variation of HAdV-3 is more than other HAdVs. Considering the clinical importance of HAdV-3 infection, its genetic diversity underscores the need for its continuous surveillance and genetic characterization.

Respiratory viruses in patients with influenza-like illness in Senegal: Focus on human respiratory adenoviruses

Background

Human adenoviruses (HAdVs) are highly contagious pathogens that are associated with a wide spectrum of human illnesses involving the respiratory tract. In the present study, we investigate the epidemiologic and viral molecular features of HAdVs circulating in Senegal after 4 consecutive years of sentinel surveillance of influenza-like Illness cases.

Methodology and results

From January 2012 to December 2015 swabs were collected from consenting ILI outpatients. Adenoviral detection is performed by rRT-PCR with the Anyplex^™ II RV16 Detection kit (Seegene) and molecular characterization was performed using a partial hexon gene sequence. 6381 samples were collected. More than half of patients (51.7%; 3297/6381) were children of ≤ 5 years. 1967 (30.8%) were positive for HAdV with 1561 (79.4%) found in co-infection with at least one another respiratory virus. The most common co-detections were with influenza viruses (53.1%; 1045/1967), rhinoviruses (30%; 591/1967), enteroviruses (18.5%; 364/1967) and RSV (13.5%; 266/1967). Children under 5 were the most infected group (62.2%; 1224/1967; p <0.05). We noted that HAdV was detected throughout the year at a high level with detection peaks of different amplitudes without any clear seasonality. Phylogenetic analysis revealed species HAdV-C in majority, species HAdV-B and one HAdV- 4 genome type. The 9 HAdV-B species like strains from Senegal grouped with genome types HAdV-7, HAdV-55 and HAdV-11 as shown by a phylogenetic branch with a high bootstrap value of (88%).

Conclusion

In conclusion, the results of the present study suggest strong year-round HAdV activity in Senegal, especially in children up to 5 years of age. Molecular studies revealed that the dominant species in circulation in patients with ILI appears to be HAdV-C and HAdV-B species. The circulation of though HAdV-7 and HAdV-55 genome types is of note as these serotypes are recognized causes of more severe and even fatal acute respiratory infections.

Fatal Community-acquired Pneumonia in Children Caused by Re-emergent Human Adenovirus 7d Associated with Higher Severity of Illness and Fatality Rate

Human adenoviruses (HAdVs) are highly contagious pathogens causing acute respiratory disease (ARD), such as community-acquired pneumonia. HAdV-7d, a re-emergent genomic variant, has been recently reported in Asia and the United States after a several-decade absence. However, whether HAdV-7d is associated with higher severity than other types is currently unclear. In this study, the clinical and epidemiological investigation showed that fever, cough, and sore throat were the three most common respiratory symptoms of HAdV infections. HAdV-7 caused longer duration of fever, higher morbidity of tachypnea/dyspnea, pleural effusion, diarrhea, hepatosplenomegaly, consciousness alteration, as well as higher rates of pneumonia, mechanical ventilation and higher fatality rate (28.6%) than other types, particularly HAdV-3 and HAdV-2. The genomes of seven HAdV-7d isolates from mild, severe, and fatal cases were sequenced and highly similar with each other. Surprisingly, two isolates (2011, 2012) had 100% identical genomes with an earlier strain from a fatal ARD outbreak in China (2009), which elucidates the virus origin and confirms the unexpected HAdV genomic conservation and stability. Phylogenetic analysis indicated that L1 52/55-kDa DNA packaging protein may be associated with the higher severity of illness and fatality rate of HAdV-7. Clinicians need to be aware of HAdVs in children with ARD.

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.

Using the E4orf6-Based E3 Ubiquitin Ligase as a Tool To Analyze the Evolution of Adenoviruses

E4orf6 proteins from all human adenoviruses form Cullin-based ubiquitin ligase complexes that, in association with E1B55K, target cellular proteins for degradation. While most are assembled with Cul5, a few utilize Cul2. BC-box motifs enable all these E4orf6 proteins to assemble ligase complexes with Elongins B and C. We also identified a Cul2-box motif used for Cul2 selection in all Cul2-based complexes. With this information, we set out to determine if other adenoviruses also possess the ability to form the ligase complex and, if so, to predict their Cullin usage. Here we report that all adenoviruses known to encode an E4orf6-like protein (mastadenoviruses and atadenoviruses) maintain the potential to form the ligase complex. We could accurately predict Cullin usage for E4orf6 products of mastadenoviruses and all but one atadenovirus. Interestingly, in nonhuman primate adenoviruses, we found a clear segregation of Cullin binding, with Cul5 utilized by viruses infecting great apes and Cul2 by Old/New World monkey viruses, suggesting that a switch from Cul2 to Cul5 binding occurred during the period when great apes diverged from monkeys. Based on the analysis of Cullin selection, we also suggest that the majority of human adenoviruses, which exhibit a broader tropism for the eye and the respiratory tract, exhibit Cul5 specificity and resemble viruses infecting great apes, whereas those that infect the gastrointestinal tract may have originated from monkey viruses that share Cul2 specificity. Finally, aviadenoviruses also appear to contain E4orf6 genes that encode proteins with a conserved XCXC motif followed by, in most cases, a BC-box motif.

IMPORTANCE

Two early adenoviral proteins, E4orf6 and E1B55K, form a ubiquitin ligase complex with cellular proteins to ubiquitinate specific substrates, leading to their degradation by the proteasome. In studies with representatives of each human adenovirus species, we (and others) previously discovered that some viruses use Cul2 to form the complex, while others use Cul5. In the present study, we expanded our analyses to all sequenced adenoviruses and found that E4orf6 genes from all mast- and atadenoviruses encode proteins containing the motifs necessary to form the ligase complex. We found a clear separation in Cullin specificity between adenoviruses of great apes and Old/New World monkeys, lending support for a monkey origin for human viruses of the Human mastadenovirus A, F, and G species. We also identified previously unrecognized E4orf6 genes in the aviadenoviruses that encode proteins containing motifs permitting formation of the ubiquitin ligase.

Outbreak of acute febrile respiratory illness caused by human adenovirus B P14H11F14 in a military training camp in Shandong China

This study reports an outbreak of acute febrile respiratory illness caused by human adenovirus B [P14H11F14] in a military training center in China between May and June 2014. In total, 164 military personnel were affected, and two patients were admitted into the intensive care unit of the military regional central hospital. A HAdV-B [P14H11F14] virus was confirmed as the etiological pathogen of this acute outbreak of febrile respiratory illness based on clinical manifestations, epidemiological characteristics, specific molecular detection results, phylogenetic analysis, and serological assays. The virus was isolated by the rhabdomyosarcoma cell culture method, and the complete sequences of the E1A, penton base, hexon, and fiber genes were determined and deposited in the GenBank database. Phylogenetic and sequence homology analyses indicated that the isolated strain is most closely related to some HAdV-55 strains from mainland China. However, this strain appeared to be less virulent than former HAdV-55 strains. According to the chest X-ray results of 31 affected patients, there was no radiological evidence of pneumonia. The most frequent symptoms in these patients were sore throat (95.12 %, 156/164) and tonsillitis (93.29 %, 153/164). During the course of the outbreak, incorrect response measures and some potential risk factors, such as fire training and marching training, may have exacerbated the spread of the infection. This outbreak illustrates the urgent need to improve the epidemiological and etiological surveillance of HAdV infections and to improve the ability of doctors and health officials in basic units of the Chinese army to respond effectively to febrile respiratory illness.

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.

A Survey of Nosocomial Respiratory Viral Infections in a Children's Hospital: Occult Respiratory Infection in Patients Admitted During an Epidemic Season

Objective:

To define the extent of shedding of respiratory viruses and Mycoplasma pneumoniae among a population of pediatric patients admitted to the hospital during a winter epidemic period and to identify nosocomial infections within this population.

Design:

An open, prospective survey of patients admitted to three wards (General Medical, Respiratory Infectious, and Infectious Diseases) of a pediatric hospital during a defined three-month period.

Patients:

All patients with medical, respiratory, and infectious conditions admitted to three wards of the Adelaide Children's Hospital had nasopharyngeal aspirations performed at the time of admission with the purpose of documenting viral and M pneumoniae shedding. Patients were monitored daily for the development of symptoms of respiratory infection or new symptoms of respiratory disease. Such patients underwent a further nasopharyngeal aspiration for the purpose of diagnosing hospital-acquired infection.

Results:

Nasopharyngeal aspirations were obtained from 601 patients. Forty-seven percent of asymptomatic patients were positive for a respiratory virus or M pneumoniae, and 61% of patients with respiratory symptoms were also positive. Gastroenteritis patients shed viruses in 66% of cases. Respiratory symptoms were initially overlooked by admitting physicians but subsequently identified in 110 cases, and 46% of these were found to be positive for a respiratory virus or M pneumoniae. There were 18 possible hospital acquired infections among the 293 initially virus-negative patients. Multiple isolates were obtained from a substantial number of patients, especially those with respiratory symptoms.

Conclusions:

A substantial proportion of all patients admitted to a pediatric hospital during winter represent a potential source of infection, and strict infection control measures should be enacted to limit the spread of these infections.

Type-specific clinical characteristics of adenovirus-associated influenza-like illness at five US military medical centers, 2009-2014

Background

Adenovirus is a recognized cause of influenza‐like illness (ILI). The proportion of ILI attributable to adenovirus is not known. Moreover, knowledge gaps remain with respect to the epidemiologic, virologic, and clinical characteristics of adenovirus‐associated ILI among otherwise healthy individuals.

Methods

An observational, longitudinal study of <65‐year‐old patients with febrile ILI at five medical centers was conducted from 2009 to 2014. Nasopharyngeal specimens obtained at enrollment were first tested by single‐reaction PCR for adenovirus, then further evaluated by a multiplex PCR assay for other respiratory viral pathogens. Symptoms over a 28‐day period were collected.

Results

We enrolled 1536 individuals, among whom 43 (2·8%) were positive for adenovirus. The median age of cases was 3·4 years (range: 4 months to 41 years). Three were hospitalized. Species and serotype information was available for 33 (76·7%) cases. Species C (n = 21) was the most common, followed by B3 (n = 9) and one each of E4a, D46, and A. Species C infections were more frequent in children (P < 0·01). Half of the cases were positive for at least one other respiratory viral pathogen. Symptoms were generally mild and most commonly included cough (90%), fatigue (79%), rhinorrhea (74%), loss of appetite (71%), and sore throat (64%). Children with non‐C adenovirus infection were more likely to report sore throat (P = 0·05) and hoarseness (P = 0·06) than those with species C infection.

Conclusions

Adenovirus is frequently detected with other respiratory viruses. Persons with non‐C adenovirus infections reported more severe symptoms, suggesting there may be species‐specific differences in virulence and/or host response to infection.

Molecular Epidemiology and Clinical Manifestations of Adenovirus Respiratory Infections in Taiwanese Children

Human adenoviruses (HAdVs) are important causes of respiratory infections in children. They usually cause mild upper respiratory symptoms, but they can also produce severe pneumonia and other complications. The aims of this retrospective study were to better define the molecular epidemiology of respiratory adenoviruses circulating in Taiwanese children during 2002 and 2013, detect reinfections and co-infections, and characterize the clinical features and laboratory findings according to the causative genotypes.We collected a representative sample of 182 isolates of adenoviruses from 175 children during the 12-year study period. The most prevalent species was HAdV-B genotype 3 (HAdV-3) (92/182, 50.5%) followed by HAdV-C (HAdV-2) (38/182, 20.9%). A single outbreak of HAdV-E (6/182, 3.3%) was noted in 2007. The mean age of children with adenovirus infections was 3.7 ± 2.0 years, with a slight predominance of males (53.1%). Children with HAdV-B tended to be older, had more lower respiratory tract infections, gastrointestinal symptoms, and a higher rate of hospitalization than those with HAdV-C (P < 0.05). Adenovirus co-infections were noted in 25/175 (14.3%) of the children. The most frequent co-infections were with species B (HAdV-3) and C (HAdV-2) (14/25, 56.0%). Additional infections were noted in 23/175 (13.1%) of the children. Of these repeated infections, the initial isolates were always genotypes of HAdV-C. The second isolates were genotypes of HAdV-B or HAdV-E. The clinical features of the first HAdV-B infection and the reinfection of HAdV-B followed the HAdV-C were similar.In conclusion, HAdV-B, C, and E were the only adenovirus species that were isolated from children who were sufficiently ill with respiratory infections to require a visit to the hospital. Human adenovirus B (HAdV-3) accounted for half of these species. HAdV-B was more likely than other species to produce severe disease. The high incidence of adenovirus co-infection and reinfections with different HAdV species supports the need for continued surveillance and has major implications for development of vaccines.

Detection and Molecular Typing of Human Adenoviruses Associated with Respiratory Illnesses in Kerala

Adenoviruses are responsible for approximately 5-10% of acute respiratory infections globally. However, there are a limited number of reports on the types of circulating respiratory human adenoviruses (HAdV) in India. We detected HAdV in the post-mortem specimens of a young child who died as a result of an acute febrile illness. To retrospectively investigate the circulating adenovirus types in the Alappuzha region, samples (n = 235) collected from patients with influenza-like illnesses who participated in the influenza surveillance program were screened for HAdV. Fourteen samples were identified as positive for adenovirus by PCR analysis. Adenovirus was isolated from 3 of the 14 PCR-positive samples cultured using HEK-293 cell lines. The viral strains isolated in the study were from children between 6 and 10 years of age. The isolates were identified as adenovirus species C and E. Sequencing analysis of the fiber gene and a BLAST search revealed that 2 of the isolates were type HAdV-C2, and the third isolate was a HAdV-E4. A fiber gene sequence-based phylogenetic tree showed that the HAdV-E4 isolate was similar to the Japanese HAdV-E4 strain, whereas the HAdV-C2 isolates formed a distinct cluster. Respiratory infections due to HAdV-E4 are generally observed in adults; this study is the first to demonstrate the involvement of the HAdV-E4 strain in respiratory illnesses in children.

Prolonged outbreak of adenovirus A31 in allogeneic stem cell transplant recipients

BACKGROUND

An outbreak of human adenovirus (HAdV) A31 occurred from December 2011 to March 2012 at the Center for Allogeneic Stem Cell Transplantation (CAST), Karolinska University Hospital in Sweden. We analyzed the outbreak, the routes of transmission, and report the medical consequences.

METHODS

The medical records of all patients admitted to CAST during the outbreak period were studied. Phylogenetic analysis of the patient HAdV strains was performed by sequencing the hexon gene and the more variable E3 gene.

RESULTS

We identified 9 cases of HAdV A31. Hygiene measures were implemented, but transmission continued for 2 months. All 9 patients had been admitted to the ward, but 2 had no connection in time to other known HAdV A31 cases. DNA sequencing of the patient strains strongly suggested nosocomial transmission. Transplantation was postponed and then cancelled in 1 patient, and 5 patients were treated with cidofovir because of high levels of viremia. In 7 patients, concomitant graft-versus-host disease (GVHD) grade II-V complicated the clinical picture, as it was difficult to distinguish symptoms of GVHD from those of HAdV infection.

CONCLUSION

An outbreak of HAdV in HSCT recipients can be difficult to control. Although none of the patients had severe disease, the medical consequences were significant. It is possible that unidentified cases with mild symptoms may have caused continuous transmission at the unit. Regular testing of all patients several weeks beyond the last case identified may be an important measure to control transmission.

Incidence of human adenoviruses and Hepatitis A virus in the final effluent of selected wastewater treatment plants in Eastern Cape Province, South Africa

BACKGROUND

Municipal effluent constitutes a large reservoir of human enteric viruses and bacteria. Contemporary monitoring practices rely on indicator bacteria, and do not test for viruses. Different viruses, including Norwalk-like viruses, Hepatitis A virus (HAV), adenoviruses, and rotaviruses, are important agents of illnesses in humans. The burden of disease caused by adenoviruses manifests as pneumonia, bronchiolitis, otitis media, conjunctivitis, and tonsillitis, whereas HAV infection can manifest as acute inflammatory diseases of the liver, fever, anorexia, malaise, nausea, and abdominal discomfort, followed by jaundice and dark urine. The public health implications of these viruses depend upon the physiological status of the wastewater microbial community.

METHODS

The occurrence of human adenovirus (HAdV) and HAV was determined in the final effluents of five wastewater treatment plants (WWTPs) in the Eastern Cape, South Africa, over 12 months (September 2012-August 2013). The viruses were detected with real-time PCR, and conventional PCR was used for serotyping.

RESULTS

Adenovirus was detected in effluent samples from all five WWTPs and in 64 % of the total samples, whereas HAV was not detected in any effluent sample. At WWPT-A, samples were collected from the final effluent tank (adenoviral concentrations ranged from 1.05 × 10(1) to 1.10 × 10(4) genome/L, with a 41.7 % detection rate) and the discharge point (adenoviral concentrations ranged between 1.2 × 10(1) and 2.8 × 10(4) genome/L, with a 54.5 % detection rate). At WWPT-B, HAdV was detected in 91.7 % of samples, with viral concentrations of 7.92 × 10(1)-2.37 × 10(5) genome/L. The HAdV concentrations at WWPT-C were 5.32 × 10(1)-2.20 × 10(5) genome/L, and the detection rate was 75 %. The adenoviral concentrations at WWPT-D were 1.23 × 10(3)-1.05 × 10(4) genome/L, and the detection rate was 66.7 %. At WWPT-E, the viral concentrations were 1.08 × 10(1)-5.16 × 10(4) genome/L, and the detection rate was 54.5 %. Characterization of the adenoviruses revealed HAdV serotypes 2 (1.4 %) and 41 (7.1 %), in species C and F, respectively.

CONCLUSIONS

This study is the first to report the prevalence of HAdV in the final effluents of WWTPs in the Eastern Cape, South Africa. The adenoviral detection rates indicate the potential contamination of the environment, with adverse effects on public health.

Accurate identification of neutralizing antibodies to adenovirus Ad36, -a putative contributor of obesity in humans

BACKGROUND

In children and adults, human adenovirus serotype 36 (Ad36) is linked with increased adiposity, and important metabolic alterations. Since this property is not shared by many other human adenovirus serotypes, it is imperative to specifically identify exposure to Ad36. Although serum neutralization assay (SNA) is the gold standard to specifically detect neutralizing antibodies (NA) to Ad36, it requires 2-weeks to complete and considerable training to interpret the results. Whereas, an enzyme-immuno assay (EIA) may provide a quicker and objective determination.

OBJECTIVES

Evaluate the accuracy of commercially available EIA kits to detect NA to Ad36. Modify SNA to reduce time and increase objectivity.

STUDY DESIGN

Sera of 15 seropositive or 16 seronegative subjects confirmed by SNA were used to test: 1) reproducibility of SNA to detect Ad36 exposure, by repeating assays twice; 2) an EIA that detects antibodies to all human adenovirus serotypes (NS-EIA) (Abcam-108705); 3) an EIA supposedly specific for Ad36 antibody (Ad36-EIA) (MyBioSource,#MBS705802), and 4) the concordance of SNA with a novel combination of SNA and immune-staining (SN-IS) kit (Cell BioLabs,#VPK-111).

RESULTS

The SNA showed exact reproducibility. NS-EIA detected adenovirus antibodies in 94% samples, confirming the non-specificity of the assay for Ad36 serotype. All seronegative samples (as determined by SNA) were false positive by Ad36-EIA. In 97% samples, SN-IS showed fidelity with Ad36-antibody status as determined by SNA.

CONCLUSIONS

The available EIA kits are not specific for detecting NA to Ad36. The modified SNA with immune-staining reduces assay time and increases accuracy of detecting by reducing subjectivity.

Human adenovirus type 7 infection associated with severe and fatal acute lower respiratory illness and nosocomial transmission

A 23-year-old male died of severe pneumonia and respiratory failure in a tertiary hospital in Beijing, and 4 out of 55 close contacts developed fever. Molecular analysis confirmed human adenovirus type 7 (HAdV7) as the causative agent. We highlight the importance of early diagnosis and treatment and proper transmission control of HAdV7.

Human adenovirus type 8: the major agent of epidemic keratoconjunctivitis (EKC)

Human adenovirus type 8 (HAdV-8) is the most common causative agent of a highly contagious eye disease known as epidemic keratoconjunctivitis (EKC). HAdV-8 strains have been classified into genome types HAdV-8A to 8K and HAdV/D1 to D12 according to restriction endonuclease analysis. This review focuses on the significance of HAdV-8 as an agent of EKC. Molecular analysis of HAdV-8 genome types HAdV-53 and HAdV-54 was performed to reveal potential genetic variation in the hexon and fiber, which might affect the antigenicity and tropism of the virus, respectively. On the basis of the published data, three patterns of HAdV-8 genome type distribution were observed worldwide: (1) genome types restricted to a microenvironment, (2) genome types distributed within a country, and (3) globally dispersed genome types. Simplot and zPicture showed that the HAdV-8 genome types were nearly identical to each other. HAdV-54 is very close to the HAdV-8P, B and E genomes, except in the hexon. In a restriction map, HAdV-8P, B, and E share a very high percentage of restriction sites with each other. Hypervariable regions (HVRs) of the hexon were conserved and were 100% identical among the genome types. The fiber knob of HAdV-8P, A, E, J and HAdV-53 were 100% identical. In phylogeny, HVRs of the hexon and fiber knob of the HAdV-8 genome types segregated into monophyletic clusters. Neutralizing antibodies against one genome type will provide protection against other genome types, and the selection of future vaccine strains would be simple due to the stable HVRs. Molecular analysis of whole genomes, particularly of the capsid proteins of the remaining genome types, would be useful to substantiate our observations.

Postinfectious bronchiolitis obliterans in children: the South American contribution

Postinfectious bronchiolitis obliterans (PIBO) is an infrequent chronic lung that causes irreversible obstruction and, or, obliteration of the smaller airways. This review particularly focuses on more than 30 studies from South America.

CONCLUSION

The initial PIBO event occurs in the early years of life and is strongly associated with adenovirus infection and the need for mechanical ventilator support. Treatment requires a multidisciplinary strategy. Multicentre studies are needed to determine progression, optimal management and long-term follow-up.

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

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

Serotype determination of adenoviruses in children with respiratory infection

OBJECTIVE

To determine adenovirus serotypes among children with acute respiratory infection (ARI) in Khoozestan province, Iran during years 2010-2011.

METHODS

One hundred sixty three nasopharyngeal swabs were collected from children between 1 and 15 y who were hospitalized for the acute respiratory infection. The viral DNA was extracted from the nasopharyngeal swabs and adenoviruses were detected by Nested PCR. Positive PCR samples were sequenced in order to confirm the adenovirus serotypes.

RESULTS

Out of 163 samples, 30 (18.4 %) were positive for adenoviruses by nested PCR. Twenty two PCR products were sequenced and recognized as Ad5 and Ad2 serotypes including 19 (86.3 %) Ad5 and 3 (13.7 %) Ad2.

CONCLUSIONS

This study reveals that adenoviruses with Ad5 predominance are important cause of respiratory tract infection in children.

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.