Seasonality of respiratory syncytial virus infection in children hospitalized with acute lower respiratory tract infections in Hunan, China, 2013-2022.

BACKGROUND: In China, respiratory syncytial virus (RSV) infections traditionally occur during the spring and winter seasons. However, a shift in the seasonal trend was noted in 2020-2022, during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: This study investigated the seasonal characteristics of RSV infection in children hospitalized with acute lower respiratory tract infections (ALRTIs). The RSV epidemic season was defined as RSV positivity in > 10% of the hospitalized ALRTI cases each week. Nine RSV seasons were identified between 2013 and 2022, and nonlinear ordinary least squares regression models were used to assess the differences in year-to-year epidemic seasonality trends. RESULTS: We enrolled 49,658 hospitalized children diagnosed with ALRTIs over a 9-year period, and the RSV antigen-positive rate was 15.2% (n = 7,566/49,658). Between 2013 and 2022, the average onset and end of the RSV season occurred in week 44 (late October) and week 17 of the following year, respectively, with a typical duration of 27 weeks. However, at the onset of the COVID-19 pandemic, the usual spring RSV peak did not occur. Instead, the 2020 epidemic started in week 32, and RSV seasonality persisted into 2021, lasting for an unprecedented 87 weeks before concluding in March 2022. CONCLUSIONS: RSV seasonality was disrupted during the COVID-19 pandemic, and the season exhibited an unusually prolonged duration. These findings may provide valuable insights for clinical practice and public health considerations.

Persistent viral shedding of human adenovirus type 7 in children with severe pneumonia.

To understand host-pathogen interactions and develop effective prevention and control strategies for human adenovirus (HAdV), it is essential to explore the characteristics of HAdV shedding. Hospitalized children <14 years who had severe HAdV pneumonia were tested for HAdV DNA by quantitative real-time PCR in nasopharyngeal aspirate (NPA). A total of 132 children were enrolled, including 102 patients with HAdV type 7 (HAdV-7) infection and 12 patients with HAdV type 3 (HAdV-3) infection. A total of 1372 qualified NPA samples were collected. There was a significant negative correlation between the viral load of HAdV and the course of the disease (Spearman r = -0.547, p = .000). HAdV-7 load decreased at a rate of 0.089 log10 copies/mL per day (95% CI: -0.096 to -0.081; R 2 = 0.332), and the duration of viral shedding was predicted to be 96.9 days (y = 8.624-0.089x). However, HAdV-3 load decreased more quickly (95% CI: - 0.229 to - 0.143; R 2 = 0.403), and the duration of viral shedding was 51.4 days (y = 9.558-0.186x). The median viral load of the HAdV-7 group at weeks 2 and 3, and more than 3 weeks postinfection was higher than that of the HAdV-3 group. No significant differences in the duration of viral shedding were found in different gender, age (>2 vs. ≤2 years), and with or without underlying diseases groups. Viral shedding in children with severe HAdV pneumonia persisted, among which HAdV-7 lasted longer than 3 months and the viral load decreased slowly than HAdV-3.

Viral loads in nasopharyngeal aspirates and tracheal aspirates among children hospitalized with invasive ventilation for human adenovirus pneumonia.

PURPOSE: To evaluate viral loads in children with human adenovirus (HAdV) pneumonia at different stages of disease and compare the viral load between upper and lower respiratory tract samples. METHODS: We prospectively enrolled children who required invasive ventilation for HAdV pneumonia. Nasopharyngeal aspirate (NPA) and tracheal aspirate (TA) samples were collected throughout the entire period of invasive ventilation. Viral detection and quantification were performed using quantitative real-time polymerase chain reaction. RESULTS: Ninety-four children were enrolled. The median age of the children was 12.0 months (IQR: 11.0-24.0), and > ninety percent of patients were aged between 6 and 59 months. Seven hundred and nine paired NPA-TA samples were collected. The median viral loads of the NPA and TA samples were 7.31 log10 and 7.50 log10 copies/mL, respectively. Viral loads generally decreased steadily over time. The median viral load after 1, 2, 3, and > 3 weeks of the disease course was 8.65, 7.70, 6.69, and 5.09 log10 copies/mL, respectively, in NPA samples and 8.67, 7.79, 7.08, and 5.53 log10 copies/mL, respectively, in TA samples. Viral load showed a significant negative correlation with time since symptom onset in both NPA samples (Spearman r = - 0.607, P = 0.000) and TA samples (Spearman r = - 0.544, P = 0.000). The predicted duration of HAdV shedding was 60.17 days in the NPA group and 65.81 days in the TA group. Viral loads in NPA and TA from the same subjects correlated well with each other (R2 = 0.694). HAdV loads in NPA and TA were most comparable during the early phase of infection (95% limits of agreement, - 1.36 to 1.30 log10 copies/mL, R2 = 0.746). Variation increased during the late phase of infection (i.e., in follow-up samples), with viral loads remaining significantly higher in TA than NPA. CONCLUSIONS: In children with HAdV pneumonia, viral loads in both NPA and TA steadily decreased during the course of the disease, and the predicted duration of viral shedding was more than 2 months. The HAdV DNA load of NPA is highly correlated with that of TA, especially in the initial phase of infection.

[Relationship between viral load of human bocavirus and clinical characteristics in children with acute lower respiratory tract infection].

OBJECTIVE: To investigate the prevalence of human bocavirus (HBoV) in children with acute lower respiratory tract infection and to explore the relationship between the viral load of HBoV and the clinical characteristics of acute lower respiratory tract infection in children. METHODS: A total of 1 554 nasopharyngeal aspirates from children who were hospitalized due to acute lower respiratory tract infection between March 2011 and March 2014 were collected. Quantitative real-time PCR was used to detect 12 RNA and 2 DNA viruses, adenovirus (ADV) and HBoV, and to measure the viral load of HBoV in HBoV-positive children. A comprehensive analysis was performed with reference to clinical symptoms and indicators. RESULTS: In the 1 554 specimens, 1 212 (77.99%) were positive for viruses, and 275 (17.70%) were HBoV-positive. In HBoV-positive cases, 94.9% were aged <3 years, and there were more males than females. In the 275 HBoV-positive cases, 45 (16.36%) had single infection, and 230 (83.64%) had mixed infection. There was no significant difference in viral load between children with single infection and mixed infection (P>0.05). The patients with fever had a significantly higher viral load than those without fever (P<0.05). The children with wheezing had a significantly higher viral load than those without wheezing (P<0.05). There was no significant difference in viral load between children with mild, moderate, and severe acute lower respiratory tract infection (P>0.05). CONCLUSIONS: HBoV is one of the important pathogens of acute lower respiratory tract infection in children. Children with a higher viral load of HBoV are more likely to experience symptoms such as fever and wheezing. However, the severity of disease and mixed infection are not significantly related to viral load.

Identification of 12 Cases of Acute Measles Encephalitis Without Rash.

Twelve cases of acute measles encephalitis without rash were identified from October 2011 to July 2013 in Changsha city, China; 5 were found to be genotype H1 and 2 were B3. Our data suggest that screening for measles virus is necessary in children with viral encephalitis, to eliminate the disease.

Immunogenicity of recombinant human bocavirus-1,2 VP2 gene virus-like particles in mice.

Human bocavirus (HBoV), a recently identified pathogen with a worldwide distribution is closely related to paediatric acute respiratory infection and gastroenteritis. The present study was performed to evaluate the immunogenicity of HBoV1 and HBoV2 virus-like particles (VLPs) as vaccine candidates in mice. Both HBoV1 and HBoV2 VLPs were expressed in the bacmid virus­SF9 cell system. Mice were inoculated three times at 3-week intervals with HBoV VLPs at one dose intramuscular (i.m.) or intradermal (i.d.) with or without the addition of the alum adjuvant. ELISA was used to detected antibody, and ELISPOT was used to test cellular immune responses. HBoV-specific IgG antibodies were induced and alum adjuvant improved the antibody titres and avidity, while the inoculation pathway had no influence. T helper type 1/ type 2 immune responses were balanced induced by HBoV1 VLPs but not HBoV2 VLPs. Serum IgG antibody cross-reactivity rates of the two subtypes were similar, but cross-reactions of HBoV1 immunization groups were higher. The single i.m. group had more interferon-γ-secreting splenocytes. These data indicate that HBoV VP2 VLPs have good immunogenicity with induction of strong humoral and cellular immune responses, and they may be potential candidate vaccines for HBoV infection.

Human bocavirus and human metapneumovirus in hospitalized children with lower respiratory tract illness in Changsha, China.

BACKGROUND: Lower respiratory tract illness is a major cause of morbidity and mortality in children worldwide, however, information about the epidemiological and clinical characteristics of LRTIs caused by HMPV and HBoV in China is limited. OBJECTIVES: Human bocavirus (HBoV) and human metapneumovirus (HMPV) are two important viruses for children with lower respiratory tract infections (LRTI). We aimed to assay the correlation between viral load and clinical characteristics of HBoV and HMPV with LRTI in Changsha, China. METHODS: Nasopharyngeal aspirates (NPAs) from children with LRTI were collected. Real-time PCR was used to screen HBoV and HMPV. Analyses were performed using SPSS 16.0 software. RESULTS: Pneumonia was the most frequent diagnosis. There was no significant difference between HBoV- and HMPV-positive patients in age (P = .506) or hospitalization duration (P = .280); 24.1% and 18.2% were positive for HBoV and HMPV. HBoV infections peaked in summer (32.2%), and HMPV infections peaked in winter (28.9%). The HBoV-positive patients had a shorter hospitalization duration than the HBoV-negative patients (P = .021), and the HMPV-positive patients had a higher prevalence of fever than the HMPV-negative patients (P = .002). The HBoV viral load was significantly higher among patients aged <1 year (P = .006). The mean HBoV and HMPV viral loads were not significantly different between patients with single infections and coinfections. Patients infected with HBoV only were older than those coinfected with HBoV and other respiratory viruses (P = .005). No significant difference was found in the clinical characteristics of patients infected with HMPV only and those coinfected with HMPV and other respiratory viruses. CONCLUSION: Pneumonia was the most frequent diagnosis caused by HBoV and HMPV. Neither HBoV nor HMPV viral load was correlated with disease severity.

[Enzyme-linked immunospot test detected specific cellular immune response induced by human bocavirus VP2 virus-like particles].

OBJECTIVE: To discuss the enzyme linked immune spot test (ELISPOT) detected the cellular immune response induced by human Bocavirus (HBoV) VP2 virus-like particles (VLPs). METHODS: After immunized by HBoV VP2 VLPs, the specific cellular immune response in mice were detected by ELISPOT assay, observe the ELISPOT results at the conditions of different polypeptide stimulate, different cell culture time, different cell concentration and different specific stimulus peptide concentration, then screening the right ELISPOT experimental conditions and establish the ELISPOT method. RESULTS: The spots induced by HBoV1 VLPs immunized mice spleen lymphocytes stimulate with polypeptide P3 (GYIPIENEL) and P5 (LYQMPFFLL)were 233 spots/10(6) cells and 157 spots/10(6) cells,spots induced by HBoV2 VLPs immunized mice spleen lymphocytes stimulate with polypeptide P8 (GYIPVIHEL) were 113 spots/10(6) cells; 24 hours is the best time for culture, at this time HBoV1 and HBoV2 groups specificity secretion IFN-gamma ratio were 232 spots/10(6) cells and 119/10(6) cells; Best concentration of mice spleen lymphocyte is 5 x 10(5), right now HBoV1 and HBoV2 group specificity secretion IFN-gamma ratio were 232 spots/10(6) cells and 108/10(6) cells; Best concentration of polypeptides is 10 microg/ml, HBoV1 and HBoV2 group specificity secretion IFN -gamma ratio were 233 spots/10(6) cells and 96/10(6) cells. CONCLUSIONS: HBoV1 and HBoV2 specificT-cell epitope in BABL/c mice were P3, P5 (HBoV1) and P8 (HBoV2). The best experiment condition were: cell cultivated for 24 h, cells concentration for 5 x 10(5) cells/well, stimulating polyperides concentration for 10 microg/ml, it can use to study the cellular immune induced by HBoV in mice.

[Virus detection in bronchoalveolar lavage fluid of 122 children with severe pneumonia].

OBJECTIVE: To investigate the prevalence of viral pathogen in children with severe pneumonia in Hunan. METHOD: Bronchoalveolar lavage fluid [BALF] were collected from 122 hospitalized children with severe pneumonia in People's Hospital of Hunan province from January 2011 to December 2011. Nested- or reverse transcription Polymerase chain reaction (PCR or RT-PCR) was used to screen Adenovirus (ADV), Human Bocavirus (HBoV), Parainfluenzaviruses1-4 (PIV1-4), Human Respiratory Syneytial virus (RSV), Influenza virus A (IFVA), Influenza virus B (IFVB), Human Rhinovirus(HRV), Human Metapneumovirus (HMPV), human coronaviruses NL63 and HKU1 (HCoV-NL63, HCoV- HKU1). RESULTS: Among the 122 bronchoalveolar lavage fluid, viral agents were detected in 60 samples(49.1%), among which ADV (40.98%) was the most common virus, followed by RSV (7.37%) and HBoV (7.37%). Two viruses were detected in 21 individual (35%) samples, of which 20 were dual positive for ADV (40%). CONCLUSION: ADV is the most frequently detected viral etiology of severe pneumonia in children in Hunan during this year. And its Coinfection with other respiratory viruses was common.

[Establishment and clinical application of TapMan real-time RT-PCR method for detection of HHV-6].

OBJECTIVE: To establish a rapid, sensitive and specific real-time PCR method for detection of Human Herpesvirus-6 (HHV-6). METHODS: According to the reference, a pair of primers and a probe were designed located in U65-66 gene and to set up the standards. We established a real-time RT-PCR method for detection of HHV-6, and to verify the specificity, sensitivity, reproducibility. RESULTS: The correlation coefficient was 0.999, E = 97.9%, the coefficient of variation values of Ct were 0.61% and 3.13% in real-time PCR assay for inter and intra assay, respectively. The results of all viruses were negative except of HHV-6 for the assay. The quantitative detection limit of the assay was 3 x 10(0) copies/microl. CONCLUSION: The real-time PCR assay is highly specific, sensitive and reproducible, which can be used to quatitative detecting clinical samples.

[The epidemiological study of adenovirus in children with respiratory tract infections in Nanjing area from 2010 to 2011].

UNLABELLED: To investigate the epidemiological features and types of human adenoviruses (ADV) in children with acute respiratory tract infection in Nanjing area, China. Nasopharyngeal aspirates and nasopharyngeal swabs were collected from 644 outpatients or hospitalized pediatric patients with ARTI at the Children Hospital of Nanjing, Jiangsu Province, China, between August 2010 and July 2011. Adenoviruses were identified and typed from the collected clinical specimens by nested-PCR based on the partial region of the hexon gene. Other 12 respiratory viruses including human bocavirus (HBoV), respiratory syncytial virus (RSV), human rhinovirus (HRV), parainfluenza viruses 1-4 (PIV1-4), influenza virus A/B (IFVA/B), human metapneumovirus (HMPV), human coronavirus NL63 and HKU1 (HCoV-HKU1 and HCoV-NL63) were also identified by PCR method. All PCR positive products were sequenced and phylogenetic analysis was conducted. It was showed that adenoviruses were detected in 171 patients out of 644 (26. 55%) children, 120 (70.18%, 120/171) for ADV3, 16 (9.36%,16/171) for ADV7, 12 (7.02%, 12/171) for ADV1, 10 (5.85%, 10/171) for ADV2, 6 (3.51%, 6/171) for ADV5, 3 (1.75%, 3/171) for ADV6, 3 (1.75%, 3/171) for ADV57, and 1 (0.58%,1/171) for ADV41. ADV infection could occur in any season. There was a higher possibility of ADV infection from April to July in 2011. Most cases (96.49%) were younger than 7 years old. A total of 99 of the 171 ADV-positive children (57.89%) were co-infected with other respiratory viruses. Respiratory syncytial virus (RSV) and human rhinovirus (HRV) were the most common additional respiratory viruses, Lower respiratory tract infections were the most frequent diagnoses made in the hospital, in which there were 52 pneumonia (30.4%) cases. CONCLUSION: ADV is one of the most important pathogens of acute respiratory tract infection in children in Nanjing area, and adenovirus type 3 was the most prevalent serotype. It is important to develop long-term surveillance.