Prevalence Of Human Bocavirus1and Correlation Between Nucleotide Mutation And Viral Loads In Hospitalized Children With Respiratory Tract Infection

Objective: To know the prevalence of HBoV1, analysis the correlationbetween viral loads and clinical manifestation in hospitalized children withrespiratory tract infection. Then analysis the sequences of HBoV1and findthe correlation between nucleotide mutation and clinical manifestation,nucleotide mutation and viral loads.Methods: NPAs were collected from846children who werehospitalized for treatment of RTI in the Department of RespiratoryMedicine at the Children’s hospital of Chongqing Medical Universitybetween June2009and May2011. Real-Time Quantitative PCR test HBoV1,analysis the correlation between viral loads and clinical manifestation. Theviral DNA extracts of the HBoV1-positive cases were sent to ShanghaiMajorbio Bio-Pharm Technology for HBoV1full and partial sequenceamplification and sequencing of the PCR products. Then analysis thesequences of HBoV1and find the correlation between nucleotide mutationand clinical manifestation, nucleotide mutation and viral loads. Data were analyzed using the SPSS17.0software package. Sequence analysis wasperformed using the MEGA5software.Results:611(72.2%) were detected at least one virus in the846NPAs.HBoV1was detected in112(13.2%) samples and more children werebetween the6months-old and2years-old group. The high viral loads ofHBoV1correlate with the pneumonia and diarrhea. Genotyping of all112HBoV1-positive cases yielded27full HBoV1sequences, as well as two NS1gene sequences,15NP1gene sequences and10VP1/VP2gene sequencesharbouring24,10and43mutations, respectively. Statistical analysisrevealed no relationship between genetic mutations and clinicalmanifestations of HBoV1-positive patients. However, the viral loads weresignificantly lower in samples with mutations G236A or A447G in NP1, orG1461A in VP1/VP2, than in samples with wild-type HBoV1.Conclusion: HBoV1was frequently detected in clinical samples fromchildren with RTI. More children were between the6months-old and2years-old group. The prevalence of HBoV1seemed more preferable tosummer. High viral loads HBoV1tend to cause LRTI and diarrhea. Whilenone of these mutations showed a relationship to the patients’ clinicalmanifestations, three mutations (G236A and A447G in NP1; G1461A in VP1/VP2) corresponded to patients with significantly lower HBoV1viralloads.