Human adenovirus (HAdV) infection in children with acute respiratory tract infections in Guangzhou, China, 2010-2021: a molecular epidemiology study.

BACKGROUND: Human adenovirus (HAdV) infection can cause a variety of diseases. It is a major pathogen of pediatric acute respiratory tract infections (ARIs) and can be life-threatening in younger children. We described the epidemiology and subtypes shifting of HAdV among children with ARI in Guangzhou, China. METHODS: We conducted a retrospective study of 161,079 children diagnosed with acute respiratory illness at the Guangzhou Women and Children's Medical Center between 2010 and 2021. HAdV specimens were detected by real-time PCR and the hexon gene was used for phylogenetic analysis. RESULTS: Before the COVID-19 outbreak in Guangzhou, the annual frequency of adenovirus infection detected during this period ranged from 3.92% to 13.58%, with an epidemic peak every four to five years. HAdV demonstrated a clear seasonal distribution, with the lowest positivity in March and peaking during summer (July or August) every year. A significant increase in HAdV cases was recorded for 2018 and 2019, which coincided with a shift in the dominant HAdV subtype from HAdV-3 to HAdV-7. The latter was associated with a more severe disease compared to HAdV-3. The average mortality proportion for children infected with HAdV from 2016 to 2019 was 0.38% but increased to 20% in severe cases. After COVID-19 emerged, HAdV cases dropped to 2.68%, suggesting that non-pharmaceutical interventions probably reduced the transmission of HAdV in the community. CONCLUSION: Our study provides the foundation for the understanding of the epidemiology of HAdV and its associated risks in children in Southern China.

Characterization of lymphocyte subsets in peripheral blood cells of children with EV71 infection.

BACKGROUND: Enterovirus 71 (EV71) is one of the major causative pathogens of hand, foot, and mouth disease (HFMD). Immune cells play a critical role in determining the outcomes of virus infection. We aimed to characterize the lymphocyte subsets and transcriptional levels of T lymphocytes-associated transcription factors in peripheral blood cells of children with EV71 infection. METHODS: Peripheral blood samples from 32 children with EV71 infection and 32 control subjects were included in this study. The frequencies of T-, B-lymphocytes, and their subsets were determined by flow cytometry. The expression of transcription factors, including T-bet, Gata3, ROR γ t, Foxp3, TCF-1, and BCL-6 in the whole blood cells were evaluated by real-time reverse-transcription quantitative polymerase chain reaction (RT-qPCR). RESULTS: The frequencies of T cells, helper T cells (Th), cytotoxic T cells (Tc), IFN-γ+ Th1, IFN-γ+ Tc1, and regulatory T (Treg) cells were significantly decreased (P < 0.01) in children with EV71 infection. As for IL-4+ Th2, IL-4+ Tc2, IL-17+ Th17, IL-17+ Tc17, follicular helper T cells (Tfh), CD3+CD8+IL-21+ T cells, CD19+ B cells, and CD19+IL-10+ B10 cells, their frequencies were significantly increased in the EV71 group (P < 0.01). The EV71 group had lower mRNA expressions of T-bet, Gata3, and Foxp3 than the control group (P < 0.05), whereas the expressions of ROR γ t, TCF-1, and BCL-6 showed no significant difference between two groups. CONCLUSIONS: EV71 infection in children caused a decreased frequency of total Th, Tc and Treg cells, and increased percentages of B cell, Th2 and Th17 cells in blood.

The Serum Value of NO and IL-17 were Increased in Children with Influenza A Viral Pneumonia.

BACKGROUND: Influenza A virus can cause severe respiratory infection in children and even result in immune system dysfunction. The aim of this study is to examine the clinical value of peripheral blood lymphocytes and serum nitric oxide (NO) and cytokines in children with influenza A viral pneumonia. METHODS: Thirty children hospitalized with confirmed influenza A viral pneumonia and 30 healthy controls were enrolled in this study. The blood samples were collected from all the children and anti-coagulated with EDTA. The peripheral blood lymphocyte subsets were analyzed by flow cytometry. Griess assay were performed to calculate serum NO and nitrite (NO2-) levels. The serum concentrations of IFN-γ and IL-17 were measured by ELISA. RESULTS: The serum levels of NO, NO2-, and IL-17 were significantly higher in children with influenza A viral pneumonia than controls (p < 0.01), while the level of IFN-γ had no significant difference (p = 0.515). Additionally, the patients had significantly lower percentages of peripheral blood CD3+, CD3+CD4+ T lymphocytes, and CD56+CD16+ natural killer (NK) cells than controls (p < 0.05), while CD3+CD8+ and CD4-CD8- (double negative, DN) T lymphocytes did not differ significantly (p > 0.05). Correlation analysis suggests that the serum NO level is positively correlated with IL-17 (p < 0.05). Conclusions: The increased levels of NO and IL-17 may be related to dysregulated lymphocytes' immune response in children with influenza A viral pneumonia. These abnormalities may be the main cause of inflammatory lung damage, and thus have significant prognostic value.

The Seroprevalence of Some Pathogen Specific IgM in Children with Acute Respiratory Tract Infections in Guangzhou Region, 2011 - 2012.

BACKGROUND: Acute respiratory tract infections (ARTIs) are the leading cause of morbidity and death in children < 5 years worldwide. The aim of this study is to analyze the seroprevalence of nine pathogen specific IgMs in children with ARTIs with respect to gender, age, and seasonality in the Guangzhou region. METHODS: Serum samples were collected from 20160 children with ARTIs admitted to the Guangzhou Women and Children's Medical Center between 2011 and 2012. Serum-specific IgM antibodies to nine respiratory pathogens, Mycoplasma pneumonia (MP), Legionella pneumophila (LP), Coxiella burnetii (C. burnetii), Chlamydophila pneumonia (CP), adenovirus (ADV), respiratory syncytial virus (RSV), type A and type B influenza virus (IVA and IVB), and parainfluenza virus (PIV), were detected using immunofluorescence assay. RESULTS: The male-to-female ratio of all patients was 1.9:1. The median age was 3 years and 8 months with a significant difference in seropositivity to respiratory tract pathogens between children from different age groups. Seropositivity was detected in 43.53% of the children with the top three pathogens being MP (33.15%), RSV (10.27%), and ADV (6.63%), followed by IVB (2.63%), LP (2.25%), IVA (1.59%), PIV (1.57%), CP (0.27%), and C. burnetii (0.13%). The prevalence of single, double, and triple seropositivity was 70.20% (6160/8775), 25.22% (2213/8775), and 4.57% (401/8775), respectively. The total IgM seropositivity for any kind of pathogen in the nine kinds of pathogens peaked in winter (46.53%), while the nadir was observed in summer (41.97%). CONCLUSIONS: The top three seroprevalence of nine kinds of pathogen specific IgM was MP, followed by RSV and ADV. The epidemic pathogen specific IgM had a season-specific seropositivity distribution. Seroprevalence of the pathogen should be a focus of attention.

[Etiology of hand, foot and mouth disease in Guangzhou in 2008].

OBJECTIVE: To understand the etiology of hand, foot and mouth disease (HFMD) in Guangzhou area in 2008. METHOD: Totally 1023 clinical specimens were collected from pediatric patients suspected of HFMD in 2008. TaqMan real-time RT-PCR were used for detection of enterovirus 71 (EV71), Coxsackievirus A16 (CA16) and other enteroviruses. The specimens which were enterovirus positive by RT-PCR method with universal primer but EV71 and CA16 negative, were amplified and sequenced for 5'untranslated region. RESULT: Enterovirus was identified from 434 of 1023 samples and detection rate of enterovirus was 42.42%; of the 434 samples, 276 were positive for EV71 (63.6%), 126 for CA16 (29%), 4 samples for enterovirus 84, 3 for Echovirus 11, 2 for Echovirus 9, 3 for Coxsackievirus B3, 4 for Coxsackievirus A10, 3 for Coxsackievirus A6, 6 for Coxsackievirus A12 or A5, and for 7 samples typing was difficult. CONCLUSION: The major causative agents of HFMD in Guangzhou were EV71 and CA16 in 2008, and EV84, CA10, CA12, CA6, COSB3, ECHV11, ECHV9 were also the pathogens for smaller proportions of patients.