Adenovirus: an overview for pediatric infectious diseases specialists

Outbreak of adenovirus D8 in a neonatal intensive care unit involving multiple simultaneous transmission pathways

BACKGROUND

Adenovirus (ADV) outbreaks in neonatal intensive care units (NICU) can lead to durable transmission and serious adverse outcomes. This study describes the investigation and control of an ADV-D8 outbreak in an NICU, associated with ophthalmologic equipment used during retinopathy of prematurity (ROP) screening. Cases were observed in neonates, parents and nurses.

METHODS

The outbreak investigation was performed including sampling patients, parents and health care workers as well as the environment for molecular detection of ADV DNA. The investigation was also conducted in the guest house where some parents were temporary residents. A retrospective cohort study focused on neonates hospitalized during the epidemic period to assess the risk associated with ROP examination.

RESULTS

Fifteen cases were identified in neonates; all but one presented with conjunctivitis. Two healthcare workers and 18 parents acquired conjunctivitis. ADV DNA was identified on the RetCam and on the freezer shared by parents. All ADV-positive samples were typed as ADV-D8. ADV infections occurred more frequently in neonates who had ROP examinations (37.8% (14/37) vs (0.9% (1/110); P<0.001) (relative risk 41.6; (5.7-305.8)). The RetCam was disinfected between two examinations using a disinfectant that was virucidal on ADV after a 30-min contact.

CONCLUSION

This outbreak was significantly associated with ROP examination with a RetCam that had a disinfection protocol ill-adapted to rapid patient turnover. In addition, nosocomial transmission via the parents to neonates and parent-to-parent transmission is likely to have played a role in the dissemination of cases. No further cases were observed after the new disinfection procedure was enforced.

mRNA- and Adenovirus-Based Vaccines against SARS-CoV-2 in HIV-Positive People

About two years have passed since the identification of SARS-CoV-2 in China. The rapid spread of this virus all over the world and its high transmissibility and pathogenicity in humans have resulted in a global pandemic. The negative impact of COVID-19 on health, society and the economy at the global level has pushed researchers and pharmaceutical companies to develop effective vaccines to fight SARS-CoV-2. Thanks to this collaborative effort, the first COVID-19 vaccine was developed in less than a year. Since then, several COVID-19 vaccines have been validated for use by the World Health Organization. Among these, mRNA- (BNT162b2 and mRNA1273) and adenovirus-based (ChAdOx1) vaccines were developed through the use of novel technologies. While all three of these vaccines have shown effectiveness against the COVID-19 disease and their immunogenicity was characterized in clinical trials in the general population, data on their efficacy and immunogenicity in people living with HIV (PLWH) are limited. In this review, we provide a description of the characteristics of mRNA- and adenovirus-based vaccines and of the immune response elicited in the general population by vaccination. Then we describe the use of these vaccines and their efficacy and immunogenicity in people living with HIV and we conclude with a discussion regarding some open questions concerning the use of mRNA- and adenovirus-based COVID-19 vaccines in PLWH.

Virus-associated disruption of mucosal epithelial tight junctions and its role in viral transmission and spread

Oropharyngeal, airway, intestinal, and genital mucosal epithelia are the main portals of entry for the majority of human pathogenic viruses. To initiate systemic infection, viruses must first be transmitted across the mucosal epithelium and then spread across the body. However, mucosal epithelia have well-developed tight junctions, which have a strong barrier function that plays a critical role in preventing the spread and dissemination of viral pathogens. Viruses can overcome these barriers by disrupting the tight junctions of mucosal epithelia, which facilitate paracellular viral penetration and initiate systemic disease. Disruption of tight and adherens junctions may also release the sequestered viral receptors within the junctional areas, and liberation of hidden receptors may facilitate viral infection of mucosal epithelia. This review focuses on possible molecular mechanisms of virus-associated disruption of mucosal epithelial junctions and its role in transmucosal viral transmission and spread.

Virus-associated disruption of mucosal epithelial tight junctions and its role in viral transmission and spread

Oropharyngeal, airway, intestinal, and genital mucosal epithelia are the main portals of entry for the majority of human pathogenic viruses. To initiate systemic infection, viruses must first be transmitted across the mucosal epithelium and then spread across the body. However, mucosal epithelia have well-developed tight junctions, which have a strong barrier function that plays a critical role in preventing the spread and dissemination of viral pathogens. Viruses can overcome these barriers by disrupting the tight junctions of mucosal epithelia, which facilitate paracellular viral penetration and initiate systemic disease. Disruption of tight and adherens junctions may also release the sequestered viral receptors within the junctional areas, and liberation of hidden receptors may facilitate viral infection of mucosal epithelia. This review focuses on possible molecular mechanisms of virus-associated disruption of mucosal epithelial junctions and its role in transmucosal viral transmission and spread.

An outbreak of acute respiratory infection at a training base in Beijing, China due to human adenovirus type B55

BACKGROUND

Twelve students experienced symptoms of acute respiratory infection (ARI) at a training base in Beijing from August 26 to August 30, 2015. We investigated the cause of this ARI outbreak.

METHODS

In partnership with the local center for disease control, we collected a total of twelve pharyngeal swab specimens as well as demographic information for the affected patients. We used multiplex real-time PCR to screen for sixteen common respiratory viruses in these samples. To isolate HAdV, we inoculated Hep-2 cells with the human adenovirus (HAdV)-positive samples and then carried out sequencing and phylogenetic analysis of the hexon, fiber, and penton genes of the isolated adenoviruses. In addition, we analyzed the entire genome of one strain isolated from the index case to identify single-nucleotide substitutions.

RESULTS

We identified ten HAdV-positive students using multiplex real-time PCR. None of the students were co-infected with other viruses. We successfully isolated seven HAdV strains from the pharyngeal swab specimens. The coding sequences of the hexon, fiber, and penton genes of these seven HAdV strains were identical, suggesting that they represented seven strains from a single virus clone. One HAdV isolate obtained from the index case, BJDX-01-2015, was selected for whole genome analysis. From this isolate, we obtained a 34,774-nucleotide sequence. The genome of BJDX-01-2015 clustered with HAdV-B55 in phylogenetic analyses and had 99.97% identity with human adenovirus 55 isolate HAdV-B/CHN/BJ01/2011/55 (GenBank accession no. JX491639).

CONCLUSIONS

We identified HAdV-B55 as the strain associated with the August 2015 ARI outbreak at a training base in Beijing. This was the first reported outbreak in Beijing due to HAdV-B55. Continuous surveillance of respiratory adenoviruses is urgently needed to understand the epidemiological and evolutionary features of HAdV-B55, and an epidemiological modeling approach may provide further insights into this emerging public health threat. Furthermore, the clinical laboratory data from this outbreak provides important reference for the clinical diagnosis and may ultimately aid in informing the development of strategies to control and prevent respiratory tract infections caused by HAdV-B55.

Human adenovirus species C recombinant virus continuously circulated in China

To date, at least three lineages (Lineage 1-3) that are related to recombinant human adenovirus species C (HAdV-C) have been identified in China. Among them, Lineage 1 includes two Chinese strains, strain KR699642-CHN-20093 (CBJ11) and strain MF315029-CHN-2013 (BJ09), which were collected in Beijing in 2009 and 2013, respectively. Herein, we performed genomic and bioinformatics analysis of two HAdV-C strains (strain SX-2000-140 and strain SX-2004-327) that were isolated from the feces of two healthy children in Shanxi province of China in 2000 and 2004, respectively. Results revealed that the genomes of both Shanxi strains had the highest homology to two Chinese HAdV-C strains belonging to Lineage 1 and harbored the genetic elements of these two strains, thereby presuming that Lineage1 has been circulated in mainland of China for decades. In addition, though the viruses in Lineage 1 showed slightly different recombinant patterns resulting from the recombinant events among the five types of HAdV-C, all the Lineage 1 viruses shared the highest sequence similarities with the HAdV-2 prototype strain (NC_001405-USA-1953) across the genome, especially in the major capsid genes including hexon, and fiber. These results indicated that Lineage 1 viruses that were associated with recombinants shared a common ancestor that is closely related to the HAdV-2 virus. Our current findings confirmed that frequent recombination among the different HAdV-C types might be an important driving force for the molecular evolution of HAdV-C. Therefore, there is a strong need for further comprehensive and systematic monitoring, detection, and research on HAdV-C.

Management of Patients With Fever and Neutropenia Through the Arc of Time: A Narrative Review

The association between fever and neutropenia and the risk for life-threatening infections in patients receiving cytotoxic chemotherapy has been known for 50 years. Indeed, infectious complications have been a leading cause of morbidity and mortality in patients with cancer. This review chronicles the progress in defining and developing approaches to the management of fever and neutropenia through observational and controlled clinical trials done by single institutions, as well as by national and international collaborative groups. The resultant data have led to recommendations and guidelines from professional societies and frame the current principles of management. Recommendations include those guiding new treatment options (from monotherapy to oral antibiotic therapy) and use of prophylactic antimicrobial regimens in high-risk patients. Of note, risk factors have changed with the advent of hematopoietic cytokines (especially granulocyte colony-stimulating factor) in shortening the duration of neutropenia, as well as with the discovery of more targeted cancer treatments that do not result in cytotoxicity, although these are still the exception. Most guiding principles that were developed decades ago-about when to begin empirical treatment after a neutropenic patient becomes febrile, whether and how to modify the initial treatment regimen (especially in patients with protracted neutropenia), and how long to continue antimicrobial therapy-are still used today. This review describes how the treatment principles related to the management of fever and neutropenia have responded to changes in the patients at risk, the microbes responsible, and the tools for their treatment, while still being sustained over the arc of time.

Outbreak of Adenovirus in a Neonatal Intensive Care Unit: Critical Importance of Equipment Cleaning During Inpatient Ophthalmologic Examinations

PURPOSE

Outbreaks of adenovirus in neonatal intensive care units (NICUs) can lead to widespread transmission and serious adverse outcomes. We describe the investigation, response, and successful containment of an adenovirus outbreak in a NICU associated with contaminated handheld ophthalmologic equipment used during retinopathy of prematurity (ROP) screening.

DESIGN

Epidemiologic outbreak investigation.

PARTICIPANTS

A total of 23 hospitalized neonates, as well as NICU staff and parents of affected infants.

MAIN OUTCOME MEASURES

Routine surveillance identified an adenovirus outbreak in a level IV NICU in August 2016. Epidemiologic investigation followed, including chart review, staff interviews, and observations. Cases were defined as hospital-acquired adenovirus identified from any clinical specimen (NICU patient or employee) or compatible illness in a family member. Real-time polymerase chain reaction (PCR) and partial- and whole-genome sequencing assays were used for testing of clinical and environmental specimens.

RESULTS

We identified 23 primary neonatal cases and 9 secondary cases (6 employees and 3 parents). All neonatal case-patients had respiratory symptoms. Of these, 5 developed pneumonia and 12 required increased respiratory support. Less than half (48%) had ocular symptoms. All neonatal case-patients (100%) had undergone a recent ophthalmologic examination, and 54% of neonates undergoing examinations developed adenovirus infection. All affected employees and parents had direct contact with infected neonates. Observations revealed inconsistent disinfection of bedside ophthalmologic equipment and limited glove use. Sampling of 2 handheld lenses and 2 indirect ophthalmoscopes revealed adenovirus serotype 3 DNA on each device. Sequence analysis of 16 neonatal cases, 2 employees, and 2 lenses showed that cases and equipment shared 100% identity across the entire adenovirus genome. Infection control interventions included strict hand hygiene, including glove use; isolation precautions; enhanced cleaning of lenses and ophthalmoscopes between all examinations; and staff furlough. We identified no cases of secondary transmission among neonates.

CONCLUSIONS

Adenovirus outbreaks can result from use of contaminated ophthalmologic equipment. Even equipment that does not directly contact patients can facilitate indirect transmission. Patient-to-patient transmission can be prevented with strict infection control measures and equipment cleaning. Ophthalmologists performing inpatient examinations should take measures to avoid adenoviral spread from contaminated handheld equipment.

Adenovirus infection among allogeneic stem cell transplant recipients

The human adenovirus (HAdV) infection can cause severe disease in immunocompromised patients, such as those undergoing allogeneic hematopoietic stem cell transplant (ASCT). The main objective of this study was to prospectively monitor ASCT recipients for HAdV occurrence in a reference center in Brazil, and also to correlate viral positivity, viral load, molecular variant, clinical symptoms, and patients' prognosis. From October/2012 to October/2014, blood and feces of 21 ASCT recipients were screened for HAdV by Nested-PCR. Viral loads were determined by real-time PCR. In total, 57% of the patients had at least one positive sample (serum or feces) for HAdV. Patients presented significantly higher viral load in feces when compared to serum. Positive samples were characterized as HAdVs of species HAdV-C, -D, and -F. The main clinical symptom presented by infected patients was diarrhea, and Graft-versus-host disease (GVHD) was the main intercurrence. An association was observed between HAdV-positivity and diarrhea and also between HAdV-positivity and GVHD. Results from this study may contribute to a better understanding of the HAdV infection pattern in patients submitted to ASCT. Data therein highlight the importance of including HAdV testing during all routine laboratory exams performed on ASCT patients. J. Med. Virol. 89:298-303, 2017. © 2016 Wiley Periodicals, Inc.

New 4-Acyl-1-phenylaminocarbonyl-2-phenylpiperazine Derivatives as Potential Inhibitors of Adenovirus Infection. Synthesis, Biological Evaluation, and Structure-activity Relationships

The search for human adenovirus (HAdV)-specific antiviral drugs for the treatment of HAdV infections in immunocompromised patients continues to be a challenging goal for medicinal chemistry. Here, we report the synthesis, biological evaluation, and structure-activity relationships of a small molecules library. We have identified six phenylpiperazine derivatives that significantly inhibited HAdV infection. These six compounds showed the capacity to block HAdV and, in addition, human cytomegalovirus (HCMV) replications at low micromolar concentration, with little or no cytotoxicity. On the basis of our biological studies, these molecules block HAdV and HCMV infections in different phases of their life cycle, providing potential candidates for the development of a new family of antiviral drugs for the treatment of infections by DNA viruses.

Molecular characterization of adenoviruses among finnish military conscripts

Although adenoviruses were identified as important respiratory pathogens many years ago, little information is available concerning the prevalence of different adenovirus serotypes, which are circulating and causing epidemics in Finnish military training centers. Over a period of five years from 2008 to 2012, 3577 respiratory specimens were collected from military conscripts presenting with symptoms compatible with acute respiratory tract infection. Upon initial testing for certain respiratory viruses by real-time PCR, 837 of these specimens were identified as adenovirus-positive. For 672 of these specimens, the serotype of the adenovirus responsible was successfully determined by DNA sequencing. Serotypes 1, 2, 3, and 4 were detected in 1, 3, 181, and 487 samples, respectively. Adenovirus epidemics were observed during each year of this study. Based on these findings, adenovirus vaccination should be considered for military conscripts in the Finnish Defence Forces.

Rotavirus and adenovirus gastroenteritis: time series analysis

BACKGROUND

This study investigated the effects of changes in weather conditions (monthly average temperature, monthly minimum temperature, monthly average humidity) on rotavirus and adenovirus gastroenteritis frequency and whether there was a seasonal correlation.

METHODS

Between 2006 and 2012, 4702 fecal samples were taken from patients ≤ 5 years of age with acute gastroenteritis; these samples were analyzed in terms of rotavirus group A and adenovirus serotype 40-41 antigens using time-series and negative binomial regression analysis.

RESULTS

Rotavirus antigens were found in 797 samples (17.0%), adenovirus antigens in 113 samples (2.4%), and rotavirus and adenovirus antigens together in 16 samples (0.3%). There was a seasonal change in rotavirus gastroenteritis (P < 0.001), and a 1°C decrease in average temperature increased the ratio of rotavirus cases in those with diarrhea by 0.523%. In addition, compared with data from other years, the number of patients was lower in the first month of 2008 and in the second month of 2012, when the temperature was below -20°C (monthly minimum temperature). There was no statistically significant relationship between adenovirus infection and change in weather conditions.

CONCLUSION

Various factors such as change in weather conditions, as well as the population's sensitivity and associated changes in activity, play a role in the spread of rotavirus infection.

Adenovirus entry from the apical surface of polarized epithelia is facilitated by the host innate immune response

Prevention of viral-induced respiratory disease begins with an understanding of the factors that increase or decrease susceptibility to viral infection. The primary receptor for most adenoviruses is the coxsackievirus and adenovirus receptor (CAR), a cell-cell adhesion protein normally localized at the basolateral surface of polarized epithelia and involved in neutrophil transepithelial migration. Recently, an alternate isoform of CAR, CAREx8, has been identified at the apical surface of polarized airway epithelia and is implicated in viral infection from the apical surface. We hypothesized that the endogenous role of CAREx8 may be to facilitate host innate immunity. We show that IL-8, a proinflammatory cytokine and a neutrophil chemoattractant, stimulates the protein expression and apical localization of CAREx8 via activation of AKT/S6K and inhibition of GSK3β. Apical CAREx8 tethers infiltrating neutrophils at the apical surface of a polarized epithelium. Moreover, neutrophils present on the apical-epithelial surface enhance adenovirus entry into the epithelium. These findings suggest that adenovirus evolved to co-opt an innate immune response pathway that stimulates the expression of its primary receptor, apical CAREx8, to allow the initial infection the intact epithelium. In addition, CAREx8 is a new target for the development of novel therapeutics for both respiratory inflammatory disease and adenoviral infection.

A Case of Adenovirus Viremia in a Pediatric Liver Transplant Recipient With Neutropenia and Lymphopenia: Who and When Should We Treat?

Human adenovirus (HAdV) is one of the most feared infections among immunocompromised patients. In particular, in liver transplant patients, HAdV has been implicated in acute liver failure with resultant mortality. The development of current molecular techniques and surveillance testing protocols have provided tools for early detection of HAdV infection, prior to or at the early onset of HAdV disease. Although reduction in immune suppression is the mainstay of therapy, many researchers have also advocated for early administration of antiviral therapy. In multiple reports, cidofovir treatment has been associated with declines in HAdV viral loads or clinical improvement in solid organ and bone marrow transplant recipients. However, there have also been case reports that raise questions about the effectiveness of antiviral therapy in controlling systemic HAdV disease. We report a case of a 26-month-old male recipient of a liver transplantation for hepatoblastoma who developed adenoviremia with an associated hepatitis and gastroenteritis. He recovered with reduced immune suppression but without antiviral therapy, thus avoiding potential toxicities associated with cidofovir therapy. This case a contrast to previous reports, and it highlights the ambiguity regarding which patients should receive HAdV-specific antiviral therapy. Additional knowledge regarding specific pediatric host factors and HAdV factors that predict poor outcomes are needed. Such information would allow clinicians to better stratify patients by risk at the time of adenoviremia detection so that low-risk patients are not unnecessarily exposed to medications with potential toxicities.

Inhibition of adenovirus replication by a trisubstituted piperazin-2-one derivative

The number of disseminated adenovirus (Ad) infections continues to increase mostly due to the growing use of immunosuppressive treatments. Recipients of solid organ or hematopoietic stem cell transplants, mainly in pediatric units, exhibit a high morbidity and mortality due to these infections. Unfortunately, there are no Ad-specific antiviral drugs currently approved for medical use. To address this situation, we used high-throughput screening (HTS) of synthetic small molecule libraries to identify compounds that restrict Ad infection. Among the more than 25,000 compounds screened, we identified a hit compound that significantly inhibited Ad infection. The compound (15D8) is a trisubstituted piperazin-2-one derivative that showed substantial antiviral activity with little or no cytotoxicity at low micromolar concentrations. Compound 15D8 selectively inhibits Ad DNA replication in the nucleus, providing a potential candidate for the development of a new class of antiviral compounds to treat Ad infections.

Meningoencephalitis due to adenovirus in a healthy infant mimicking severe bacterial sepsis

We present the case of a previously healthy 15-month-old girl with acute adenovirus infection who had features of severe bacterial sepsis and meningitis. Real-time qPCR done on cerebrospinal fluid identified adenovirus as the causative agent allowing stopping antibiotic treatment. The patient subsequently recovered without sequelae. An overview of published and unpublished data on adenovirus central nervous system infection in immunocompetent children is presented.

Enhancement of enteric adenovirus cultivation in a novel Ras-overexpressing cell line

Enteric human adenoviruses (HAdVs; serotypes 40 and 41) have been identified as an emerging cause of drinking water contamination. Due to their fastidious characteristics, HAdVs are difficult to cultivate and therefore not detected easily by standard mammalian cell cultivation methods. Here we found that human embryonic kidney 293 cells, transformed transiently with Ras, enhanced HAdV replication by more than threefold. We also constructed a stable cell line overexpressing the Ras protein, 293-Ras, in which the replication of three HAdV strains of serotypes 40 and 41 was increased markedly. However, only HAdV replication was enhanced; infection of 293 and 293-Ras cells with human rhinivorus-6 showed no significant differences in replication rate. Infected 293-Ras cells exhibited an increased level and phosphorylation of extracellular regulated kinase (ERK). In addition, the Ras-mediated increase in HAdV replication was impaired by the mitogen-activated protein kinase/ERK kinase (MEK1) inhibitor U0126, suggesting direct involvement of the MEK1/ERK pathway in enhanced HAdV replication. Based on these results, we suggest that the 293-Ras cell line be used for the efficient detection and cultivation of HAdV strains in both clinical and environmental specimens.