Objective:To determine the changes of immune-associated molecules in serum of patients infected with respiratory syncytial virus subtype A (RSV-A).Methods:Serum specimens were collected from patients with respiratory infection at Department of Pediatrics of NO. 2 Clinical Teaching Hospital of Chengde Medical University during August 2022 to June 2023. The serum specimens were set as RSV-A single infection group and RSV-A coinfection group based on the detected pathogens in these patients. Serum levels of Th1 cytokines including interferon γ (IFN-γ) and tumor necrosis factor-α (TNF-α), and Th2 cytokines including interleukin 4 (IL-4) and IL-10, soluble toll-like receptor 2 (sTLR2) and 4 (sTLR4), soluble tumor necrosis factor receptor 1 (sTNFR1) and sTNFR2 were determined using enzyme-linked immunosorbent assay (ELISA) kits.Results:Serum levels of IFN-γ ( H=10.030, P=0.007) and IL-4 ( H=10.246, P=0.006) were significantly up-regulated in RSV-A single infection group and RSV-A coinfection group, however, levels of TNF-α ( F=1.154, P=0.322) and IL-10 ( F=1.738, P=0.188) were not significantly up-regulated. Area under the curve (AUC) of IFN-γ and IL-4 were 0.866 (95% CI: 0.767-0.966, P=0.002) and 0.986 (95% CI: 0.956-1.000, P=0.001), respectively. The levels of sTLR2 ( H=1.165, P=0.559) and sTLR4 ( H=1.657, P=0.437) were not significantly changed. Levels of sTNFR1 ( H=11.431, P=0.003) and sTNFR2 ( F=3.411, P=0.041) were significantly up-regulated in RSV-A coinfection group and the concentration of sTNFR2 was higher than sTNFR1. Concentration of sTNFR1 was peaked in RSV-A coinfected with bacterium group and RSV-A coinfected with dual bacteria group. AUC of sTNFR2 was 0.967 (95% CI: 0.911-1.000, P=0.002). Conclusions:Expressions of immune-associated molecules, including IFN-γ, IL-4, sTNFR1 and sTNFR2 were significantly changed in patients infected with RSV-A, and these immune-associated molecules maybe engage in the interaction and pathogenesis between RSV-A and host.

Objective:To analyze the prevalence and clinical features of respiratory syncytial virus (RSV) in Chengde city.Methods:From August 2022 to June 2023, throat swabs and clinical data of 478 hospitalized children with respiratory tract infection in the Chengde Central Hospital were collected. Real-time quantitative PCR was used to detect the molecular epidemiology of RSV-A and RSV-B subtypes and analyze the clinical features of patients with RSV infection.Results:Among the hospitalized children, 67.57% (323/478) tested positive for RSV. The outbreak of RSV infection was caused by RSV-A subtype. The peaks of RSV-A infection occurred from November to December, 2022 and May to June, 2023. There were 86.07% (278/323) of the RSV-A-positive cases had mixed infection with other pathogens, primarily bacterial pathogens with Streptococcus pneumoniae being the most common, followed by Klebsiella pneumoniae. Influenza virus A was the most common viral pathogens causing mixed infection. The level of lactate dehydrogenase was higher in the patients with single RSV-A infection than in those with mixed infection ( Z=2.396, P=0.017), and higher than the normal upper limit. Compared with the single infection group, the mixed infection group had higher white blood cell count ( Z=2.417, P=0.016), neutrophil ratio ( Z=3.218, P=0.001), C-reactive protein level ( Z=1.998, P=0.046) and creatinine level ( Z=2.107, P=0.035), and lower lymphocyte ratio ( Z=3.205, P=0.001), but they were all within the normal range. There were no significant differences in the clinical features between RSV-A-positive patients co-infected with bacteria or other viruses (all P>0.05). Conclusions:RSV-A is the leading cause of respiratory tract infection in children in Chengde from 2022 to 2023, and often co-detected with bacteria. The mixed infection with other respiratory pathogens is related to the clinical features of patients with RSV-A infection.