A significant outbreak of respiratory human adenovirus infections among children aged 3-6 years in Hokkaido, Japan, in 2023.

Human adenovirus (HAdV) infections present diverse clinical manifestations upon infecting individuals, with respiratory infections predominating in children. We surveyed pediatric hospitalizations due to respiratory HAdV infections across 18 hospitals in Hokkaido Prefecture, Japan, from July 2019 to March 2024, recording 473 admissions. While hospitalizations remained below five cases per week from July 2019 to September 2023, a notable surge occurred in late October 2023, with weekly admissions peaking at 15-20 cases from November to December. There were dramatic shifts in the age distribution of hospitalized patients: during 2019-2021, 1-year-old infants and children aged 3-6 years represented 51.4%-54.8% and 4.1%-13.3%, respectively; however, in 2023-2024, while 1-year-old infants represented 19.0%-20.1%, the proportion of children aged 3-6 years increased to 46.2%-50.0%. Understanding the emergence of significant outbreaks of respiratory HAdV infections and the substantial changes in the age distribution of hospitalized cases necessitates further investigation into the circulating types of HAdV in Hokkaido Prefecture and changes in children's neutralizing antibody titers against HAdV.

High-Frequency Recombination of Human Adenovirus in Children with Acute Respiratory Tract Infections in Beijing, China.

Recombination events in human adenovirus (HAdV) have led to some new highly pathogenic or infectious types. It is vital to monitor recombinant HAdVs, especially in children with acute respiratory tract infections (ARIs). In the retrospective study, HAdV positive specimens were collected from pediatric patients with ARIs during 2015 to 2021, then typed by sequence analysis of the penton base, hexon and fiber gene sequence. For those with inconsistent typing results, a modified method with species-specific primer sets of a fiber gene sequence was developed to distinguish co-infections of different types from recombinant HAdV infections. Then, plaque assays combined with meta-genomic next-generation sequencing (mNGS) were used to reveal the HAdV genomic characteristics. There were 466 cases positive for HAdV DNA (2.89%, 466/16,097) and 350 (75.11%, 350/466) successfully typed with the most prevalent types HAdV-B3 (56.57%, 198/350) and HAdV-B7 (32.00%, 112/350), followed by HAdV-C1 (6.00%, 21/350). Among 35 cases (7.51%, 35/466) with inconsistent typing results, nine cases were confirmed as co-infections by different types of HAdVs, and 26 cases as recombinant HAdVs in six genetic patterns primarily clustered to species C (25 cases) in pattern 1-5, or species D (1 case) in pattern 6. The novel recombinant HAdV of species D was identified with multiple recombinant events among HAdV-D53, HAdV-D64, and HAdV-D8, and officially named as HAdV-D115. High-frequency recombination of HAdVs in six genetic recombination patterns were identified among children with ARIs in Beijing. Specifically, there is a novel Adenovirus D human/CHN/S8130/2023/115[P22H8F8] designed as HAdV D115.

Human adenoviruses in children with gastroenteritis: a systematic review and meta-analysis.

PURPOSE: Human adenoviruses (HAdVs) have always been suggested as one of the main causes of gastroenteritis in children. However, no comprehensive report on the global epidemiology of these viruses in pediatric gastroenteritis is available. METHODS: A systematic search was conducted to obtain published papers from 2003 to 2023 in three main databases PubMed, Scopus, and Web of Science. RESULTS: The estimated global pooled prevalence of HAdV infection in children with gastroenteritis was 10% (95% CI: 9-11%), with a growing trend after 2010. The highest prevalence was observed in Africa (20%, 95% CI: 14-26%). The prevalence was higher in inpatients (11%; 95% CI: 8-13%) and patients aged 5 years old and younger (9%; 95% CI: 7-10%). However, no significant difference was observed between male and female patients (P = 0.63). The most prevalent species was found to be the species F (57%; 95% CI: 41-72%). The most common HAdVs observed in children with gastroenteritis were types 40/41, 38, and 2. Analysis of case-control studies showed an association between HAdV and gastroenteritis in children (OR: 2.28, 95% CI; 1.51-3.44). CONCLUSION: This study provided valuable insights into the importance of HAdVs in children with gastroenteritis, especially in hospitalized and younger children. The results can be used in future preventive measurements and the development of effective vaccines.

Molecular characterization of human adenoviruses associated with pediatric respiratory infections in Karachi, Pakistan.

Human adenoviruses (HAdVs) are a diverse group of viruses associated with respiratory infections in humans worldwide. However, there is a lack of research on the genetic diversity and epidemiology of HAdVs in Pakistan. This study characterized HAdVs in pediatric patients with respiratory tract infections in Karachi, Pakistan, between 2022 and 2023. We analyzed 762 nasopharyngeal samples of children ≤ 5 years. DNA extraction, followed by PCR targeting E2B and hexon genes, was carried out. Data analysis was performed on SPSS 25.0, and phylogenetic analysis of hexon gene was performed on MEGA 11. HAdV was detected in 7.34% (56/762) of patients round the year, but at a significantly higher rate during the winter season. Age was insignificantly associated with HAdV incidence (p = 0.662), but more than 62.5% (35/56) of positive cases were younger than 10 months. The circulating HAdVs were identified as six different types from species B (78.57%) and C (21.42%), with the majority of isolates found to be like B3. HAdV was found to be co-infected with bocavirus (5.4%) and measles (7.14%). These findings revealed a high frequency and genetic diversity of respiratory HAdVs in Karachi, Pakistan. We conclude that periodic and continuous surveillance of adenoviruses and other respiratory pathogens is necessary to improve the prognosis and management of respiratory diseases, thereby reducing the child mortality rate in Pakistan.

Useful manifestations to detect adenovirus in children with upper respiratory infections: A retrospective study.

OBJECTIVE: Approximately 1 million adenovirus immunochromatography (IC) kits are annually used in Japan. However, no practical strategies have been developed regarding their use for detecting adenovirus. The present study aims to verify the usefulness of clinical manifestations in making decisions regarding the use of adenovirus IC kits for children with upper respiratory infections (URI). METHODS: The medical records of 825 pediatric cases tested by IC kits for adenovirus were extracted from clinical laboratory department database over a 3-year period at our hospital. Among them, 585 patients were suspected adenovirus URI, and their clinical manifestations were reviewed. After data cleaning, 10 types of clinical manifestations were statistically analyzed between adenovirus IC kit-positive and -negative groups. Multivariate analysis was performed to select significant clinical manifestations using adenovirus IC kit positivity as the objective variable. RESULTS: Among 585 pediatric patients, the cases of 420 patients, with suitable data for whom no other pathogen was detected, were reviewed. Adenovirus was detected in 86 cases. Multivariate analysis identified a significant difference for three clinical manifestations: (1) fever ≥ 39.0°C, (2) rhinorrhea, and (3) tonsillar exudate. The negativity rate for the IC kit was 90% when none of the three manifestations was observed. CONCLUSIONS: The results suggested that IC kits for adenovirus tend to give negative results in cases that lack all the three above mentioned clinical manifestations.

Outbreak of Acute Respiratory Illness Associated With Human Adenovirus Type 4 at the United States Coast Guard Academy, 2019.

BACKGROUND: Although a human adenovirus (HAdV) vaccine is available for military use, officers-in-training are not routinely vaccinated. We describe an HAdV-associated respiratory outbreak among unvaccinated cadets at the US Coast Guard Academy and its impact on cadet training. METHODS: We defined a case as a cadet with new onset cough or sore throat during August 1-October 4, 2019. We reviewed medical records and distributed a questionnaire to identify cases and to estimate impact on cadet training. We performed real-time polymerase chain reaction testing on patient and environmental samples and whole genome sequencing on a subset of positive patient samples. RESULTS: Among the 1072 cadets, 378 (35%) cases were identified by medical records (n = 230) or additionally by the questionnaire (n = 148). Of the 230 cases identified from medical records, 138 (60%) were male and 226 (98%) had no underlying conditions. From questionnaire responses, 113 of 228 (50%) cases reported duty restrictions. Of cases with respiratory specimens, 36 of 50 (72%) were HAdV positive; all 14 sequenced specimens were HAdV-4a1. Sixteen (89%) of 18 environmental specimens from the cadet dormitory were HAdV-positive. CONCLUSIONS: The HAdV-4-associated outbreak infected a substantial number of cadets and significantly impacted cadet training. Routine vaccination could prevent HAdV respiratory outbreaks in this population.

Genomic analyses of human adenoviruses unravel novel recombinant genotypes associated with severe infections in pediatric patients.

Human adenoviruses (HAdVs) are highly contagious pathogens of clinical importance, especially among the pediatric population. Studies on comparative viral genomic analysis of cases associated with severe and mild infections due to HAdV are limited. Using whole-genome sequencing (WGS), we investigated whether there were any differences between circulating HAdV strains associated with severe infections (meningitis, sepsis, convulsion, sudden infant death syndrome, death, and hospitalization) and mild clinical presentations in pediatric patients hospitalized between the years 1998 and 2017 in a tertiary care hospital group in Bern, Switzerland covering a population base of approx. 2 million inhabitants. The HAdV species implicated in causing severe infections in this study included HAdV species C genotypes (HAdV1, HAdV2, and HAdV5). Clustering of the HAdV whole-genome sequences of the severe and mild cases did not show any differences except for one sample (isolated from a patient presenting with sepsis, meningitis, and hospitalization) that formed its own cluster with HAdV species C genotypes. This isolate showed intertypic recombination events involving four genotypes, had the highest homology to HAdV89 at complete genome level, but possessed the fiber gene of HAdV1, thereby representing a novel genotype of HAdV species C. The incidence of potential recombination events was higher in severe cases than in mild cases. Our findings confirm that recombination among HAdVs is important for molecular evolution and emergence of new strains. Therefore, further research on HAdVs, particularly among susceptible groups, is needed and continuous surveillance is required for public health preparedness including outbreak investigations.

Characterization of Tonsil Microbiota and Their Effect on Adenovirus Reactivation in Tonsillectomy Samples.

The adenoviral DNA is prevalent in adenotonsillectomy specimens from pediatric patients, though the virus seems to be in latent state. The tonsils are at the forefront of airway entry point and are the first line of defense against airway viral and bacterial infections. We hypothesized that tonsil microbiota plays a role in human adenovirus (HAdV) latency and reactivation. In this study, we surveyed the presence of HAdV in tonsillectomy samples from 81 patients and found that HAdV DNA was in 85.2% of the tonsil samples. We then determined the microbiota of the samples. Taxonomic profiling showed that Proteobacteria, Firmicutes, Fusobacteriota, and Bacteroidota accounted for approximately 70% of the total phyla in tonsil samples. A correlation analysis showed that the HAdV-positive samples had significantly higher abundance of Neisseria and Bifidobacterium and lower abundance of Streptococcus, Ochrobactrum, and Lactobacillus than that of the HAdV-negative samples. Culture-based isolation followed by 16S rRNA sequencing identified Staphylococcus aureus, Streptococcus pneumoniae, Veillonella, Prevotella, Capnocytophaga sputigena, Pseudomonas aeruginosa, Neisseria, and Moraxella catarrhalis from the samples. Gas chromatography-mass spectrometry (GC-MS) profiling of short-chain fatty acids in bacterial cultures of minced tonsillectomy tissues or representative isolates showed the cultures contained various amounts of short-chain fatty acids (SCFAs). Treatment of isolated tonsil lymphocytes with bacterial lipopolysaccharide (LPS) or with SCFAs promoted HAdV reactivation. The compounds also promoted HAdV reactivation in a xenograft model with implanted tonsil fragments. This study shows a potential interplay between tonsil microbiota and HAdV reactivation that may lead to recurrent virus infection of respiratory tract disease. IMPORTANCE Human adenovirus infection is common among pediatric patients and can be life-threatening among organ transplant recipients. Adenovirus is transmitted by close contact, but it is believed that a majority of invasive events appear to arise from viral reactivation. The human tonsil is a reservoir for virus latency and has a high prevalence of latently infected adenovirus. Also, tonsils are located at the gateway of the respiratory tracts and are commonly exposed to bacterial pathogens. Here, we uncovered adenoviral DNA-positive and -negative samples that appeared to harbor distinct distribution patterns of microorganisms. SCFAs, primary metabolites of microbiota on tonsils, could induce the adenovirus reactivation in tonsil lymphocytes, resulting in adenovirus replication and production of infectious virions. The study suggests that viral-bacterial interaction plays a role in virus reactivation from latency and could be a contributing factor for recurrent viral infection in pediatric patients.

Comparison of 11 respiratory pathogens among hospitalized children before and during the COVID-19 epidemic in Shenzhen, China.

BACKGROUND: The effect of SARS-CoV-2 on existing respiratory pathogens in circulation remains uncertain. This study aimed to assess the impact of SARS-CoV-2 on the prevalence of respiratory pathogens among hospitalized children. METHODS: This study enrolled hospitalized children with acute respiratory infections in Shenzhen Children's Hospital from September to December 2019 (before the COVID-19 epidemic) and those from September to December 2020 (during the COVID-19 epidemic). Nasopharyngeal swabs were collected, and respiratory pathogens were detected using multiplex PCR. The absolute case number and detection rates of 11 pathogens were collected and analyzed. RESULTS: A total of 5696 children with respiratory tract infection received multiplex PCR examination for respiratory pathogens: 2298 from September to December 2019 and 3398 from September to December 2020. At least one pathogen was detected in 1850 (80.5%) patients in 2019, and in 2380 (70.0%) patients in 2020; the detection rate in 2020 was significantly lower than that in 2019.The Influenza A (InfA) detection rate was 5.6% in 2019, but 0% in 2020. The detection rates of Mycoplasma pneumoniae, Human adenovirus, and Human rhinovirus also decreased from 20% (460), 8.9% (206), and 41.8% (961) in 2019 to 1.0% (37), 2.1% (77), and 25.6% (873) in 2020, respectively. In contrast, the detection rates of Human respiratory syncytial virus, Human parainfluenza virus, and Human metapneumovirus increased from 6.6% (153), 9.9% (229), and 0.5% (12) in 2019 to 25.6% (873), 15.5% (530), and 7.2% (247) in 2020, respectively (p < 0.0001). CONCLUSIONS: Successful containment of seasonal influenza as a result of COVID-19 control measures will ensure we are better equipped to deal with future outbreaks of both influenza and COVID-19.Caused by virus competition, the detection rates of Human respiratory syncytial virus, Human parainfluenza virus, and Human metapneumovirus increased in Shenzhen,that reminds us we need to take further monitoring and preventive measures in the next epidemic season.

Enteric adenovirus epidemiology from historical fecal samples in Brazil (1998-2005): Pre-rotavirus vaccine era.

Human adenovirus (HAdV) is recognized as frequent cause of acute gastroenteritis and enteric viruses can be preserved in frozen stored feces for long periods of times. The purpose of the present study was to investigate enteric HAdV genotypic diversity in archival fecal specimens stored from 1998 to 2005 in order to understand the natural history of HAdV in diarrheal patients in Brazil before rotavirus vaccine introduction. A total of 3346 specimens were tested for HAdV using conventional PCR. Genotypes were identified by sequencing. HAdV was detected in 6.8% (228/3346). Positivity was higher in children ≤ 5 years and males (p < 0.05). HAdV was most frequently observed during winter and spring seasons (p < 0.05). HAdV-F41 was the most prevalent genotype (59.2%;135/228), followed by HAdV-F40 (16.2%;37/228), HAdV-C1 (5.2%;12/228), HAdV-C2 (5.2%;12/228), HAdV-C5 (3.1%;7/228), HAdV-A12 (1.3%;3/228), HAdV-E4 (0.9%;2/228), HAdV-B3 (0.9%;2/228) and HAdV-B21 (0.4%;1/228). In 7.6% (17/228) only species D could be defined. HAdV-E4 strains were phylogenetic analyzed and classified as lineage (a)-like PG II. HAdV prevalence remained stable in Brazilian population, regardless rotavirus vaccine introduction. The predominant HAdV genotypes detected did not change over time, highlighting a high diversity of circulating strains in the country throughout decades. Due to the historical lack of HAdV genotyping surveillance in Brazil, HAdV-E4 epidemiology is virtually unknown in the country. The present study contributed significantly to the understanding of the natural history of HAdV in diarrheal patients in Brazil. The acquired data are important for clinical diagnosis, particularly for studies investigating enteric viruses' prevalence and molecular epidemiology of archival clinical specimens.

Nonenteric Adenoviruses Associated with Gastroenteritis in Hospitalized Children.

The object of this study was to investigate the frequency of human adenovirus (HAdV) infections in hospitalized pediatric patients. Stool samples were collected during a 1-year period (February 2018 to January 2019). HAdV was detected by a broad-range PCR and genotyped by sequencing and phylogenetic analysis. Demographic characteristics and detailed clinical information were analyzed for each patient. HAdV was detected in 7.1% of stool samples (34/476). Among these patients, 23.5% were coinfected with other enteric viral or bacterial pathogens. The majority (85.2%) of HAdV positives were detected in children of <5 years of age. Two HAdV species (B and C) with three types were identified in this study population. HAdV species F was not detected. Genetic analysis shows that the isolates circulating in our region present high diversity and do not exhibit clonal expansion. The presence of nonenteric HAdV in subjects with gastrointestinal symptoms and in immunocompromised patients has already been reported by different studies and underlines the need to develop routine molecular assays that have wide reactivity for most types of adenovirus in order to obtain an optimal tool for their rapid and accurate diagnosis. IMPORTANCE Gastroenteritis is the second leading cause of death among infants and children worldwide. Our study shows that adenovirus types other than 40 and 41 might be related to acute gastroenteritis. Therefore, a novel approach using diagnostic methods able to detect all adenovirus types is desirable in order to overcome the limitations of the current techniques.

Development and evaluation of a loop-mediated isothermal amplification assay for clinical diagnosis of respiratory human adenoviruses emergent in China.

Three human adenovirus (HAdV) genotypes, HAdV-7, HAdV-14, and HAdV-55, emerged as the most prevalent variants in China over the past decade and caused both sporadic, fatal cases and frequent, large outbreaks. Early diagnosis is essential to control infections and endemics. Here, we established a loop-mediated isothermal amplification (LAMP) assay coupled with an instrument-free nucleic acid extraction device recently developed by our group; the assay could detect all the 3 prevalent HAdV genotypes. Specificity analysis showed no cross-reactivity with other common respiratory pathogens and the analytical sensitivity was as low as 10 copies/µL. All detection steps could be completed within 1 hour. The assay's performance was evaluated using clinical samples and compared with the gold standard RT-PCR method, showing highly consistent results. The LAMP assay developed here could be readily used in basic laboratory facilities and with minimal DNA extraction equipment, and as a reliable screening test in a resource-limited setting.

Genetic characterization and phylogenetic variations of human adenovirus-F strains circulating in eastern India during 2017-2020.

Human adenovirus-F (HAdV-F) (genotype 40/41) is the second-most leading cause of pediatric gastroenteritis after rotavirus, worldwide, accounting for 2.8%-11.8% of infantile diarrheal cases. Earlier studies across eastern India revealed a shift in the predominance of genotypes from HAdV41 in 2007-09 to HAdV40 in 2013-14. Thus, the surveillance for HAdV-F genotypes in this geographical setting was undertaken over 2017-2020 to analyze the viral evolutionary dynamics. A total of 3882 stool samples collected from children (≤5 years) were screened for HAdV-F positivity by conventional PCR. The hypervariable regions of the hexon and the partial shaft region of long fiber genes were amplified, sequenced, and phylogenetically analyzed with respect to the prototype strains. A marginal decrease in enteric HAdV prevalence was observed (9.04%, n = 351/3882) compared to the previous report (11.8%) in this endemic setting. Children <2 years were found most vulnerable to enteric HAdV infection. Reduction in adenovirus-rotavirus co-infection was evident compared to the sole adenovirus infection. HAdV-F genotypes 40 and 41 were found to co-circulate, but HAdV41 was predominant. HAdV40 strains were genetically conserved, whereas HAdV41 strains accumulated new mutations. On the basis of a different set of mutations in their genome, HAdV41 strains segregated into 2 genome type clusters (GTCs). Circulating HAdV41 strains clustered with GTC1 of the fiber gene, for the first time during this study period. This study will provide much-needed baseline data on the emergence and circulation of HAdV40/41 strains for future vaccine development.

Respiratory viruses in the healthy middle ear and middle ear with otitis media with effusion.

To investigate the presence of respiratory viruses in the middle ear cavity of the individuals with a healthy middle ear and the children with otitis media with effusion (OME). A total of 72 middle ear samples were collected from 25 children with OME (Group 1) and 47 individuals with no middle ear disease (Group 2). Multiplex real-time polymerase chain reaction was used to investigate the presence of 20 different respiratory viruses. Virus results were compared with bacteriomes of the same populations. At least one respiratory virus was detected in 56% of the patients in Group 1 and 12.8% of the individuals in Group 2. The viral co-infection rate for Group 1 and 2 was 8% and 2.1%, respectively. In Group 1, adenovirus was the most frequently detected virus with a rate of 24%, either alone (16%) or concurrent with other viruses (8%), followed by influenza B (12%), rhinovirus, and bocavirus (8%) each. Parainfluenza 4, coronavirus OC43, and RSV A/B were detected in 4% of the sample each. In Group 2, rhinovirus was detected in two samples (4.3%) followed by adenovirus, coronavirus OC43, coronavirus E299, and coronavirus NL63 with a rate of 2.1% each. The detection rate of respiratory viruses was significantly higher in children aged 6 to 11 years. There was no positive association between virus and bacteria found in the middle ear cavity. The current study has provided comprehensive data indicating the presence of diverse respiratory viruses in the healthy middle ear cavity. Our results also suggest that respiratory viruses might have a contribution to OME pathogenesis.

Rapid identification and metagenomics analysis of the adenovirus type 55 outbreak in Hubei using real-time and high-throughput sequencing platforms.

The rise in human adenovirus (HAdV) infections poses a serious challenge to public health in China. Real-time (RT) sequencing provides solutions for achieving rapid pathogen identification during outbreaks, whereas high-throughput sequencing yields higher sequence accuracy. In the present study, we report the outcomes of applying nanopore and BGI platforms in the identification and genomic analysis of an HAdV outbreak in Hubei province, China in May of 2019. A mixed sample of nine nasopharyngeal swabs and one single sample were submitted to direct nanopore sequencing (MinION device), generating their first HAdV-55 reads within 13 and 20 min, respectively. The sequences were confirmed by RT-polymerase chain reaction (PCR). Ten HAdV-positive samples were further sequenced using next-generation high-throughput sequencing (BGISEQ-500 device). Phylogenetic analysis revealed that the outbreak strain had a close genetic relation to strains isolated in Sichuan province. Metagenomic analysis showed that HAdV-55 was not a dominant species in samples from which the whole HAdV-55 genome could not be assembled. The present results highlight the value of combining sequencing platforms and using mixed samples for nucleic acid enrichment in pathogen detection of infectious disease outbreaks.

Epidemiology of enteric virus infections in children living in the Amazon region.

OBJECTIVES: To verify the frequency of viruses causing acute gastroenteritis (AGE) in association with the histo-blood group antigen (HBGA) and Rotarix™ vaccination coverage in children from the Amazon region. DESIGN: Fecal and saliva samples were collected from children with AGE (n = 485) and acute respiratory infection (ARI) (n = 249) clinical symptoms. Rotavirus A (RVA), norovirus, human adenovirus (HAdV), and sapovirus (SaV) were verified in feces by molecular detection. Saliva samples were used for HBGA phenotyping/FUT3 genotyping. Blood group types, clinical aspects and Rotarix™ RVA vaccination data were recorded. RESULTS: Norovirus remained the most prevalently detected cause of AGE (38%, 184/485 and ARI 21.3%, 53/249). High HAdV frequencies were observed in AGE children (28.6%, 139/485) and ARI children (37.3%, 93/249). RVA was the third most prevalent virus causing AGE (22.7%, 110/485 and ARI 19.3%, 48/249) and a low RV1 coverage (61%, 448/734) was verified. The SaV frequencies were lower (7.2%, 35/485 for AGE and 6.8%, 17/249 for ARI). Secretor children were HBGA susceptible to HAdV infection (OR 1.5, 95% CI 1.0-2.3; P = 0.04) but not to RVA, norovirus or SaV infection. CONCLUSIONS: Norovirus could be considered the main etiological agent of AGE. No association was verified for HBGA susceptibility to RVA, norovirus and SaV. Secretor children showed a slight susceptibility to HAdV infection and the Le (a-b-) heterogeneous SNPs on the FUT3 gene.

Quantitative Investigation of Viral Load in Acute to Subacute Human Adenovirus Type 54 Conjunctivitis.

To understand the clinical course of human adenoviral (HAdV) conjunctivitis and establish a better treatment regimen, 38 eyes of 19 patients with HAdV-54 conjunctivitis for less than one week from onset were evaluated for clinical signs and symptoms and DNA copy numbers. A viral load of 104-105 is required to develop symptoms of HAdV conjunctivitis, as symptoms were present in eyes with viral loads of ≥104 at least once during the course. Next, it was observed that asymptomatic infections in the contralateral eyes are common, as the virus was detected in most eyes that did not develop conjunctivitis. Furthermore, there was no rapid decrease in the viral load in healed eyes; on the contrary, the viral load in the healed eyes on day 15 was significantly higher than that in the unhealed eyes. This was likely due to corticosteroid instillation, which rapidly alleviated symptoms but prolonged the duration of viral shedding. Recently, combination treatment with iodine and corticosteroids has been recommended for HAdV conjunctivitis. Assessing changes in the viral load and clinical symptoms would be helpful to better understand the clinical course of this disease.

CACO-2 cells: A continuous cell line with sensitive and broad-spectrum utility for respiratory virus culture.

BACKGROUND: Primary rhesus monkey kidney cells (RhMK) can be used for the detection of respiratory viruses, including influenza and parainfluenza. The human colon adeno-carcinoma cell line, CACO-2, has been previously used for the growth of multiple influenza viruses, including seasonal, novel and avian lineages. OBJECTIVE: We compared CACO-2, Madin-Darby Canine Kidney (MDCK), and RhMK cells for the isolation of viruses from patients presenting with influenza like-illness (ILI). STUDY DESIGN: Nasopharyngeal specimens from patients with ILI in primary care settings were processed for conventional viral culture in MDCK, RhMK, and CACO-2. Cells were examined microscopically for cytopathic effect (CPE) and confirmatory testing included immunofluorescent antigen (IFA) detection and real-time RT-PCR. Additionally, 16 specimens positive for respiratory syncytial virus (RSV) by PCR were inoculated on CACO-2 cells. Statistical analysis was done using Chi-square test with IBM Statistical Program. RESULTS: Of 1031 respiratory specimens inoculated, viruses were isolated and confirmed from 331 (32.1 %) in MDCK cells, 304 (29.5 %) in RhMk cells, and 433 (42.0 %) in CACO-2 cells. These included influenza A/(H1N1)pdm09, influenza A(H3N2), influenza B, parainfluenza virus (PIV) types 1, 2, and 3, human coronavirus 229E (CoV-229E), human adenovirus (HAdV), herpes simplex virus 1 (HSV 1), and enterovirus (EV). Influenza A viruses grew best in the CACO-2 cell line. Time to observation of CPE was similar for all three cell types but unlike RhMK and MDCK cells, virus-specific morphological changes were indistinguishable in CACO-2 cells. None of the 16 specimens positive for RSV by PCR grew on CACO-2 cells. CONCLUSIONS: The overall respiratory virus culture isolation rate in CACO-2 cells was significantly higher than that in RhMK or MDCK cells (p < 0.05). CACO-2 cells also supported the growth of some viruses that did not grow in either RhMK or MDCK cells. Except for RSV, CACO-2 cells provide a worthwhile addition to culture algorithms for respiratory specimens.

Genotypes and phylogenetic analysis of adenovirus in children with respiratory infection in Buenos Aires, Argentina (2000-2018).

Human adenoviruses (HAdV) are one of the most frequent causes of respiratory infections around the world, causing mild to severe disease. In Argentina, many studies focused on the association of HAdV respiratory infection with severe disease and fatal outcomes leading to the discovery in 1984 of a genomic variant 7h associated with high fatality. Although several molecular studies reported the presence of at least 4 HAdV species (B, C, D and E) in Argentina, few sequences were available in the databases. In this study, sequences from the hexon gene region were obtained from 141 patients as a first approach to assess the genetic diversity of HAdVs circulating in Buenos Aires, Argentina. Phylogenetic analysis of these sequences and others recovered from public databases confirmed the circulation of the four above-mentioned species represented by 11 genotypes, with predominance in species B and C and shifts in their proportion in the studied period (2000 to 2018). The variants detected in Argentina, for most of the genotypes, were similar to those already described in other countries. However, uncommon lineages belonging to genotypes C2, C5 and E4 were detected, which might indicate the circulation of local variants and will deserve further studies of whole-genome sequences.