Isolation and characterization of a novel recombinant human adenovirus species D

Molecular epidemiology of circulating human adenoviruses among acute respiratory infection patients seeking healthcare facilities in West Bengal, India

Human adenovirus (HAdV) causes acute respiratory infections leading to mortality in children. This study analyzes the circulating respiratory HAdV genotypes in West Bengal, India during 2018-2022 among symptomatic patients. The overall positivity rate was 6.8%, out of which 26.4% were co-infected with other respiratory viruses. Children aged 2 to 5 years were mostly infected. Phylogenetic analysis revealed that the recombinant HAdV-B type 7/3, which has remarkable outbreak potential, predominantly circulated in this region followed by the non-recombinant HAdV-B type 3/3. Moreover, the amino acid sequences encoded by both the hexon and fiber genes of these two circulating strains possessed a few mutations that mostly diverged from the prototype strain, although the divergence was less pronounced in case of the amino acids encoded by the fiber gene of HAdV-B type 3/3. Overall, the results underscore the need for continuous surveillance of respiratory HAdV types to combat future possible epidemics.

Seroprevalence and molecular characterization of human respiratory syncytial virus and human adenovirus among children in Ado-Ekiti, Nigeria

In children, the respiratory syncytial virus and adenovirus majorly cause acute respiratory infections. The study evaluated the seroprevalence and conducted the molecular characterization of human respiratory syncytial virus (HRSV) and human adenovirus (HAdV) among children. Venous blood, nasopharyngeal, and oropharyngeal swabs were collected from children presenting with acute respiratory infections in a tertiary health facility in Ado-Ekiti, Nigeria. A serological investigation was carried out on the sera samples for the detection of anti-HRSV immunoglobulin M (IgM), anti-HRSV IgG, anti-HAdV IgM, and anti-HAdV IgG using ELISA (enzyme-linked immunosorbent assay) kits. The amplification and sequencing of HRSV and HAdV were carried out using specific primer pairs that targeted the glycoprotein (G) gene of HRSV and the hexon gene of HAdV, respectively. The seroprevalence of HRSV IgG and IgM was 73% and 7.5%, respectively, while the seroprevalence of HAdV IgG and IgM was 98.5% and 8.5%, respectively. The age of enrolled children, presence of fever, and cough were associated (p < 0.05) with the infection. HRSV subtype B (HRSV-B) (13.3%), and species of HAdV (Mastadenovirus B and C) (11.7%) were detected among the studied population. There was no viral coinfection with both HRSV and HAdV. In infancy and early childhood, HRSV-B, HAdV species B and C are common etiologic agents of respiratory infections as reported in this study. Further studies on molecular characterization of respiratory tract viruses including circulating respiratory syncytial virus and adenovirus are hereby advocated.

First isolation of human adenovirus type 85 by molecular analysis of adenoviruses in cases of urethritis

Introduction. Human adenovirus (HAdV) has been reported as a potential cause of sexually transmitted urethritis.Aim. We aimed to investigate HAdVs associated with urethritis in Osaka, Japan through molecular characterization.Methodology. Urine samples were obtained from male patients with urethritis from 2015 to 2018. Molecular analysis of the isolated strains and follow-up real-time polymerase chain reaction analyses of the clinical samples were performed.Results. The isolates were classified into five types belonging to species D (18 cases) or E (one case). HAdV-85 (species D) was detected for the first time in a urethritis case. Follow-up examination demonstrated that HAdV was isolated from urine samples half a month after the first sampling in four cases, and that viral DNA could be detected after 1 month in two cases.Conclusion. The HAdV types detected from urethritis cases were related to respiratory and ocular HAdV infections, while a novel HAdV type identified as a cause of conjunctivitis also causes urethritis. Sexual contact should be avoided for 1 month after HAdV genital infection.

Intestinal HAdV Infection: Tissue Specificity, Persistence, and Implications for Antiviral Therapy

Human adenovirus (HAdV) causes infections predominantly in early childhood and the tissue tropism of specific HAdV species determines the clinical manifestation, including infections of the gastrointestinal tract, respiratory tract, and keratoconjunctivitis. Why HAdV shows such a tropism has not yet been fully elucidated, but in the intestine different mechanisms for virus entry or resistence to immune modulatory factors have been described. Recently identified antiviral strategies by interferons provide evidence about the repression of E1A and maybe even promote HAdV persistence. The presence of HAdV in a persistent status in the gut is of importance in the setting of pediatric stem cell transplant recipients where HAdV detection in stool usually preceds clinical signs and severe infections are related to mortality. The reactivation of persistent intestinal HAdV infections in these patients needs further investigation also with regard to successful therapy options. In addition, several newly identified recombinant HAdV types have been isolated from stool samples, thus raising the question of possible recombination events in the gut. In this review, intestinal HAdV infections are discussed in relation to the tissue tropism, persistence, recombination, and new in-vitro models to enhance the knowledge about virus–host interactions and support the development of new treatment approaches.

Human adenovirus among hospitalized children with respiratory tract infections in Beijing, China, 2017-2018

BACKGROUND

Human adenoviruses (HAdVs) cause a wide range of diseases. However, the genotype diversity and epidemiological information relating to HAdVs among hospitalized children with respiratory tract infections (RTIs) is limited. Here, we describe the epidemiology and genotype distribution of HAdVs associated with RTIs in Beijing, China.

METHODS

Nasopharyngeal aspirates (NPA) were collected from hospitalized children with RTIs from April 2017 to March 2018. HAdVs were detected by a TaqMan-based quantitative real-time polymerase chain reaction (qPCR) assay, and the hexon gene was used for phylogenetic analysis. Epidemiological data were analyzed using statistical product and service solutions (SPSS) 21.0 software.

RESULTS

HAdV was detected in 72 (5.64%) of the 1276 NPA specimens, with most (86.11%, 62/72) HAdV-positives cases detected among children < 6 years of age. HAdV-B3 (56.06%, 37/66) and HAdV-C2 (19.70%, 13/66) were the most frequent. Of the 72 HAdV-infected cases, 27 (37.50%) were co-infected with other respiratory viruses, most commonly parainfluenza virus (12.50%, 9/72) and rhinovirus (9.72%, 7/72). The log number of viral load ranged from 3.30 to 9.14 copies per mL of NPA, with no significant difference between the HAdV mono- and co-infection groups. The main clinical symptoms in the HAdV-infected patients were fever and cough, and 62 (86.11%, 62/72) were diagnosed with pneumonia. Additionally, HAdVs were detected throughout the year with a higher prevalence in summer.

CONCLUSIONS

HAdV prevalence is related to age and season. HAdV-B and HAdV-C circulated simultaneously among the hospitalized children with RTIs in Beijing, and HAdV-B type 3 and HAdV-C type 2 were the most frequent.

Phylogenetic evidence for intratypic recombinant events in a novel human adenovirus C that causes severe acute respiratory infection in children

Human adenoviruses (HAdVs) are prevalent in hospitalized children with severe acute respiratory infection (SARI). Here, we report a unique recombinant HAdV strain (CBJ113) isolated from a HAdV-positive child with SARI. The whole-genome sequence was determined using Sanger sequencing and high-throughput sequencing. A phylogenetic analysis of the complete genome indicated that the CBJ113 strain shares a common origin with HAdV-C2, HAdV-C6, HAdV-C1, HAdV-C5, and HAdV-C57 and formed a novel subclade on the same branch as other HAdV-C subtypes. BootScan and single nucleotide polymorphism analyses showed that the CBJ113 genome has an intra-subtype recombinant structure and comprises gene regions mainly originating from two circulating viral strains: HAdV-1 and HAdV-2. The parental penton base, pVI, and DBP genes of the recombinant strain clustered with the HAdV-1 prototype strain, and the E1B, hexon, fiber, and 100 K genes of the recombinant clustered within the HAdV-2 subtype, meanwhile the E4orf1 and DNA polymerase genes of the recombinant shared the greatest similarity with those of HAdV-5 and HAdV-6, respectively. All of these findings provide insight into our understanding of the dynamics of the complexity of the HAdV-C epidemic. More extensive studies should address the pathogenicity and clinical characteristics of the novel recombinant.

Adenovirus infection in children with acute lower respiratory tract infections in Beijing, China, 2007 to 2012

Background

Human adenoviruses (HAdV) play a significant role in pediatric respiratory tract infections. To date, over 60 types of HAdV have been identified. Here, HAdV types are characterized in children in the Beijing area with acute lower respiratory tract infections (ALRTIs) and the clinical features and laboratory findings of hospitalized HAdV-infected cases are described.

Methods

Respiratory specimens were collected from pediatric patients with ALRTIs in the emergency department or from those admitted to Beijing Children’s Hospital between March 2007 and December 2012. Infections with common respiratory viruses were determined by PCR or RT-PCR. HAdV positive samples were further typed by PCR and sequencing.

Results

Among 3356 patients with ALRTIs, 194 (5.8 %) were found to have HAdV infection. HAdV infection was primarily confined to children (88.35 %) less than 5 years of age. A total of 11 different types of HAdV were detected throughout the study period, with HAdV-B7 (49.0 %) and HAdV-B3 (26.3 %) as the most prevalent types, followed by HAdV-C2 (7.7 %) and HAdVC1 (4.6 %). Newly emerging and re-emergent types or variants, HAdV-B55 (n = 5), HAdV-C57 (n = 3), and HAdV-B14p1 (n = 1), were identified. Results also included the reported first case of co-infection with HAdV-C2 and HAdV-C57. Clinical entities of patients with single HAdV infection (n = 49) were similar to those with mixed HAdV/respiratory syncytial virus (RSV) infections (n = 41). Patients with HAdV-B7 infection had longer duration of fever and higher serum levels of muscle enzymes than HAdV-B3-infected patients.

Conclusions

During the study period, HAdV-B7 and HAdV-B3 were the predominant types identified in pediatric ALRTIs. HAdV-B7 infection tends to have more severe clinical consequences. The presence of newly emerging types or variants and co-infection with different types of HAdV highlights the need for constant and close surveillance of HAdV infection.

Targeting species D adenoviruses replication to counteract the epidemic keratoconjunctivitis

Human adenoviruses are non-enveloped DNA viruses causing various infections; their pathogenicity varies dependent on virus species and type. Although acute infections can sometimes take severe courses, they are rarely fatal in immune-competent individuals. Adenoviral conjunctivitis and epidemic keratoconjunctivitis are hyperacute and highly contagious infections of the eye caused by human adenovirus types within species D. Currently there is no causal treatment available to counteract these diseases effectively. The E2B region of the adenovirus genome encodes for the viral DNA polymerase, which is required for adenoviral DNA replication. Here we propose novel model systems to test this viral key factor, DNA polymerase, as a putative target for the development of efficient antiviral therapy based on RNA interference. Using our model cell lines we found that different small interfering RNAs mediate significant suppression (up to 90%) of expression levels of viral DNA polymerase upon transfection. Moreover, permanent expression of short hairpin RNA based on the most effective small interfering RNA led to a highly significant, more than tenfold reduction in replication for different human group D adenoviruses involved in ocular infections.

Identification of a novel intertypic recombinant species D human adenovirus in a pediatric stem cell transplant recipient

BACKGROUND

Human adenoviruses (HAdV) are known opportunistic pathogens in hematopoietic stem cell transplant (SCT) recipients. The detection of HAdV infection in children after SCT has been implicated as a determinant of poor outcome but specific associations between HAdV species or individual HAdV types and disease are poorly understood.

OBJECTIVES

Characterization of a HAdV-D strain isolated from multiple clinical specimens of an 11-year-old female recipient of a matched unrelated donor peripheral SCT for T-cell lymphoma and case report.

STUDY DESIGN

Archived HAdV PCR-positive plasma, urine, and stool specimens were processed for virus isolation and detailed molecular typing. Complete genomic sequencing was carried out on 2 isolates.

RESULTS

The patient tested positive for HAdV DNA by real-time PCR of a stool specimen at 44 days after initiation of a SCT conditioning regimen. In the subsequent 3 months, HAdV was detected in plasma, urine and stool specimens in association with symptoms of gastroenteritis and hemorrhagic cystitis. A novel HAdV-D with a HAdV20-like hexon gene was isolated from both urine and stool specimens. All isolates yielded identical restriction profiles with endonucleases BamHI, BglII, BstEII, HindIII, PstI and SmaI. Analysis of 2 complete genomic sequences further identified the virus as a novel intertypic recombinant HAdV-D (P20/H20/F42) closely related to HAdV42.

CONCLUSIONS

This case highlights the identification of a previously unknown HAdV-D from an immunocompromised host. In this patient, the course of adenovirus infection is compatible with reactivation of a latent virus or a primary opportunistic infection. Adenoviremia in this patient resolved without definitive adenovirus-directed antiviral therapy.

Human adenovirus: Viral pathogen with increasing importance

The aim of this review is to describe the biology of human adenovirus (HAdV), the clinical and epidemiological characteristics of adenoviral epidemic keratoconjunctivitis and to present a practical update on its diagnosis, treatment, and prophylaxis. There are two well-defined adenoviral keratoconjunctivitis clinical syndromes: epidemic keratoconjunctivitis (EKC) and pharyngoconjunctival fever (PCF), which are caused by different HAdV serotypes. The exact incidence of adenoviral conjunctivitis is still poorly known. However, cases are more frequent during warmer months. The virus is endemic in the general population, and frequently causes severe disease in immunocompromised patients, especially the pediatric patients. Contagion is possible through direct contact or fomites, and the virus is extremely resistant to different physical and chemical agents. The clinical signs or symptoms of conjunctival infection are similar to any other conjunctivitis, with a higher incidence of pseudomembranes. In the cornea, adenoviral infection may lead to keratitis nummularis. Diagnosis is mainly clinical, but its etiology can be confirmed using cell cultures, antigen detection, polymerase chain reaction or immunochromatography. Multiple treatments have been tried for this disease, but none of them seem to be completely effective. Prevention is the most reliable and recommended strategy to control this contagious infection.