Circular genome of human bocavirus 1 associated with high load of viral DNA, positive antigen and increased risk of severe pneumonia in children

BACKGROUND: Human bocavirus 1 (HBoV1) causes acute respiratory infections (ARIs) in children, but its diagnosis is complicated by prolonged viral shedding. There are indications that the detection of a circular genome in a clinical specimens may be associated with acute infection. METHODS: Respiratory specimens collected from pediatric patients with ARIs during January 2021 to July 2024 were screened by a duplex qPCR, which was developed to distinguish circular genome from total viral genomes and evaluated by nested PCR and antigen test. Clinical data were collected from patients with single HBoV1 infection to reveal the association of circular genome with ARIs and the severity of pneumonia. RESULTS: ) copies/mL in the circular genome negative group (p < 0.0001). In the antigen-positive group, the positive rate for circular genomes was 78.57 % (44/56), significantly higher than 34.29 % (108/315) observed in the antigen-negative group. Among patients single positive for HBoV1, the circular genome-positive group (n = 106) showed more severe clinical manifestations and required more intensive treatment. Logistic regression analysis identified the circular genome as a strong independent risk factor for severe pneumonia (OR = 6.38, AUC = 0.82). CONCLUSION: Circular genome of HBoV1 associated with high load of viral DNA, positive antigen and severe pneumonia in children may serve as a biomarker for acute HBoV1 infection and severe pneumonia.