Detection Of Human Bocavirus In Children With Acute Lower Respiratory Tract Infection

Objective： To study different detection methods of human bocavirus (HBoV)including sputa HBoV DNA detection, serum serological detection, serum HBoV DNAdetection, and bronchoalveolar lavage fluids (BALF) HBoV DNA detection in childrenwith acute lower respiratory tract Infection (ALRI).Method：From January to April of2013, samples including serums, sputa and BALFwere obtained from714children hospitalized with ALRI. Serums were tested for HBoVspecial IgG and IgM antibodies by ELISA and all kinds of samples were tested for HBoVDNA by quantitative real-time fluorescent PCR. Detection results of HBoV DNA in sputa,its serology and their combination were compared with those of HBoV DNA in serumsand/or BALF, which was considered as the standard. Their consistence and differenceswere evaluated, and the diagnostic parameters including sensitivity, specificity, postivepredict value, negative predict value, consistent rate, and J value were calculated. Agedistributions and co-infections of the HBoV positive patients tested by serology combingsputa DNA and serums and/or BALF DNA were also compared.Result：(1) The positive rate of the four detection methods were：sputa HBoV DNA14.3%(102/714)，HBoV serology13.2%（94/714），BALF HBoV DNA7.3%（7/96）,serum HBoV DNA6.0%（43/714），altogether21.6%（154/714）.(2) Sputa HBoV DNAdetection result was consistent with that of HBoV DNA in serums and/or BALF(χ2=91.834, P <0.001). And serums and/or BALF HBoV DNA positive children weresignificantly more in children with high load HBoV DNA in sputa than those with lowload（χ2=29.646，P<0.001）. Dectection results of HBoV serology and its combination withsputa HBoV DNA were consistent with the standard (χ2=124.662,138.643, P all<0.001）.(3) The positive rate of the former three methods were also proved to be betterthan the standard by McNemar test (χ2=23.547,33.440,12.410, P all <0.001）.(4) The sensitivity, specificity, positive predict value, negative predict value, consistent rate, and Jvalue were:58.3%,90.1%,29.8%,96.8%,88.0%,0.484（Kappa=0.335, P<0.001）forserology；68.8%,89.6%,32.4%,97.5%,88.2%,0.584(Kappa=0.384, P<0.001）for sputaDNA detection；70.4%,94.8%,38.0%,98.6%,93.7%,0.65(Kappa=0.463, P<0.001）fortheir combination, respectively.(5) HBoV positive children testing serology combiningsputa DNA or serums and/or BALF DNA were mainly under3years of age，especially ingroup～1year. And no differences were observed between the combined detection andthe standard in each age group（P all>0.05）, whereas differences were significant when itcomes to the positive rate tested by the two methods in different age groups（χ2=58.303,35.053，P all <0.05），the positive rate were both highest in group～1year, and group～3years next. However, it was lowest in group>3years by the former test but in group～6months by the latter..(6)The co-infection rate of sputa HBoV DNA positive children wassignificantly higher than those of HBoV serological positive children and the standardpositive children（χ2=9.138,10.036, P all <0.05）. No differences were observed of thetotal co-infection rate and the respective co-infection rate of virus, bacteria and MPbetween the detection by combination of HBoV serology and sputa HBoV DNA and thestandard（χ2=0.102,1.965,1.022,0.022，P all>0.05）.Conclusion：HBoV DNA detections in serums and BALF are great methods for thediagnosis of HBoV ALRI, and it can enhance the detection positivity. High load of sputaHBoV DNA was closely relative with the infection in the lower respiratory tract.Diagnostic power can be improved and age distributions and co-infections can bedemonstrated when serology is combined with traditional sputa DNA detection for HBoV.