| Objective: The aim of this study is to investigate the HBV prevalence and the infection pattern of blood donors,detect the effect on HBV positive rate by different screening methods,follow up the occult HBV infection(OBI)in blood donors,and analyze the genotype of the HBV strains by S gene sequencing.It would offer references for donor recruitment and provide regional guidance for the recognition and prevention of Hepatitis B virus(HBV)in Qingdao.Methods: HBsAg ELISA and nucleic acid amplification test(NAT)were used to detect the blood samples from 643771 blood donors in Qingdao during 2013 to 2018.The characteristics of HBV positive blood donors,including age,gender,education and donor status(primary donors vs repetitive donors)were analyzed.A proportion of HBsAg positive samples were confirmed by neutralization method.HBsAg-/HBV DNA+ and HBsAg+/ HBV DNA+ samples were further tested with viral load assay and serological testing for five serological markers(HBsAg,HbsAb,HBeAg,HbeAb and HbcAb).Partial donors with HBsAg-/HBV DNA+ were followed up and repeatedly tested for viral load and five serological markers.The sequence of HBV S gene was detected by PCR and sequencing,and the amino acid sequences of the samples were analyzed by the phylogenetic tree and compared with consensus sequences of HBV and sequences of wild HBV strains in GenBank.Results:(1)A total of 1624 cases of HBV positive samples were identified,includes HBsAg+/HBV DNA-892 cases(0.139%),HBsAg-/HBV DNA+ 316 cases(0.049%),and HBsAg+/HBV DNA+ cases 416(0.065%).(2)The rate of HBsAg+/HBV DNA-or HBsAg+/HBV DNA+ was higher in 2015 than other years(P<0.05).The total positive rate of HBV and the positive rate of HBsAg+/HBV DNA+ increased with age from 18 to 55 years old(P< 0.05),and the positive rate of HBsAg-/HBV DNA+ increased with age from 18 to 60 years old(P< 0.05).The positive rate of HBsAg+/HBV DNA-was higher in blood donors under 45 years old,with highest rate in group of aged 26 to 35(P<0.05).There was no significant difference in the total positive rate of HBV between sexes,but the positive rate of HBsAg+/HBV DNA-in males was lower than that in females,and the detection rate of HBsAg-/HBV DNA+ or HBsAg+/HBV DNA+ in males was higher than that in females(P<0.05).The positive rate of all cases decreased gradually with the increase of educational background(P<0.05).The total positive rate of HBV,the positive rate of HBsAg+/HBV DNA-and HBsAg+/HBV DNA+ in primary donors was significantly higher than that of repetitive donors(P<0.05).(3)The confirmed positive rate in the samples with double reactive HBsAg result was significantly higher than that in the samples with single positive result(P<0.05).(4)Among 62 HBsAg-/HBV DNA+ samples,25 were quantitatively negative and 47 were quantitatively positive,of which 27 were HBV DNA <20 IU/ml and 20 were > 20 IU/mL.All the 12 samples of HBsAg+/HBV DNA+ were quantitatively positive,2 samples of HBV DNA < 20 IU/ml and 10 samples of HBsAg+/HBV DNA < 20 IU/ml.A total 53 of 62 HBsAg-/HBV DNA+ samples were positive for HBcAb+(85.48%),of which 26 cases(41.94%)were HBcAb+ alone and 13 cases(20.97%)were HBsAb+/HBcAb+.Follow-up of 32 HBsAg-/HBV DNA+ donors revealed that one case had HBsAg+,HBeAb+,HBcAb+ in two tests,one case belonged to window period of HBV infection,one case belonged to transient HBV infection,22 cases were OBI,and 7 cases needed to further determine whether HBV DNA was positive.(5)Five cases of OBI and 13 cases of HBsAg+ blood donors were successfully sequenced.Among of them,4 cases of OBI and 5 cases of HBsAg+ samples were genotype B,1 OBI and 8 cases of HBsAg+ samples were genotype C.Two cases of OBI samples had mutations in the main hydrophilic region(MHR)of HBsAg which are associated with immune escape and OBI,and 3 cases of HBsAg+ samples also had mutations in the MHR region.Conclusion:(1)Age,educational background,repeated blood donation and detection methods all affect the detection rate of HBV in blood donors.Blood donors should be recruited rationally,the formation of repetitive blood donors should be strengthened,and the detection methods should be updated to reduce the risk of blood transfusion and avoid the unnecessary loss of blood donors.(2)HBsAg-/HBV DNA+ blood donors have high detection rate of HBcAb and low viral load,with the highest OBI ratio.The current screening strategy which combined ELISA and NAT reduces the transfusion transmitted risk of HBV from both window phase and OBI and improves blood safety.(3)The dominating HBV genotypes in blood donors from Qingdao are genotype B and C and the mutations on HBsAg may be related to the formation of OBI. |
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