These mutations in genotype D or various other genotypes strongly affected HBsAg detection by altering HBV-antigenicity or viral-particle maturation . Contamination Prevalence We studied 186 infants who received HB vaccination and their FCGR2A 181 HBsAg-positive mothers. The age of the infants ranged from one to 51 months, with a mean age of 16.0513.06 months, and there were 99 (53.22%) males and 87 (46.77%) females. The 186 infants had finished two-dose or three-dose injections of HB vaccine according to their vaccination schedule, and 128 (68.81%) had received HBIG injections (100 IU) after birth. HBsAg was detected by ELISA using Kehua assay, and 3 infants tested positive. Then, HBV DNA was detected by real-time PCR and nested PCR in SB-505124 the other 183 infants who were unfavorable for HBsAg (Fig. 1). Six infants had detectable HBV DNA, and their viral loads ranged from 103 to 107 IU/mL (Table 2). We also performed nested PCR after real-time PCR and obtained gene fragments of HBV for sequencing. Five infant sera were positive for both the S and C genes fragments, 2 were positive for both the P and C genes fragments, and 2 were positive for the S, P and C genes fragments (Table 2). Altogether, 6 infants tested positive for HBV DNA by real-time PCR and nested PCR. Another 3 infants had HBV DNA that were only detectable by nested PCR. The 9 infants identified as HBV DNA positive were re-tested for HBsAg by Abbott reagents; none were positive. We obtained 9 infants with OBI who tested positive for HBV DNA but unfavorable for HBsAg in the serum. The prevalence of OBI in infants received neonatal HB vaccination from HBsAg-positive mothers was 4.92% (9/183), with a 95% CI of 1 1.79% to 8.05%. Other serological markers were also assayed in the subjects. Among the 186 infants, 77.96% (145/186) had anti-HBs SB-505124 and 33.87% (63/186) had anti-HBc. Open in a separate window Physique 1 Diagram showing the diagnostic workflow of assessments for identifying occult HBV contamination in infants (+ve, positive; ?ve, unfavorable). Table 2 HBV DNA levels in 9 infants diagnosed with occult HBV contamination. thead CodeHBV DNA (IU/mL)Nested PCRS genePre-C/C geneP gene /thead 200129300000+++20047720+++200542700++?20089630++?2058 100++?10121490++?20159600++?2067 100?++3039 100?++ Open in a separate window Factors Associated with Occult HBV Contamination in Infants The demographics, serological markers and epidemiological data for the 9 occult infection infants are listed in Table 3. These 9 infants included 2 females and 7 males, and their mean age was 11.0013.06 months. There were no significant differences in the SB-505124 age and gender ratio between OBI-positive and OBI-negative infants (Table 4, em P /em 0.05). Although all infants had been immunized with two-dose and three-dose HB vaccine according to vaccination schedule, HBIG was not administered to every infant. Two of 9 SB-505124 (22.22%) OBI-positive infants and 54 of 174 (31.03%) OBI-negative infants did not receive HBIG after birth. HBIG usage and HBV vaccine injection occasions were not associated with occult contamination. In HBV infected infants including 3 HBsAg-positive and SB-505124 9 OBI infants, 66.66% (8/12) received two doses vaccine, which was obvious higher than non-infection infants (31.03%, 54/174). It showed that incomplete three-dose injections of HB vaccine was associated with HBV contamination ( em P /em ?=?0.022). Table 3 Demographics, serological markers and epidemiological data for the 9 OBI infants. thead CodeGenderAge (months)HB vaccine injection timesHBIGAnti-HBs (mIU/mL)Anti-HBcMaternal HBeAgMaternal HBV DNA (IU/mL) /thead 2001Male1.552 doseNo- + +4.0E82004Male38.403 doseYes- ? ?145000.02005Male2.052 doseYes32 ? ? 1002008Male1.062 doseYes13 ? ?7920.02058Male2.012 doseYes28 ? ? 1001012female7.653 doseYes61 ? ?2060.02015Male6.142 doseYes97 ? ?9680.02067female14.393 doseYes59 ? +7.23E73039Male25.793 doseNo – ? ? 100 Open in a separate window Table 4 Univariate analysis of factors associated with occult HBV contamination among HB-vaccinated infants. thead FactorsOBI-positive infants (n?=?9)OBI-negative infants (n?=?174) em p /em OR (95% CI) /thead Age (months)11.0013.0616.4413.040.228Gender (male/female)7/290/840.1763.27 (0.66,16.17)HB vaccine injection times1 (2 doses/3 doses)5/454/1200.1502.78 (0.72,10.75)HBIG71200.7241.58 (0.32,7.83)Anti-HBs positivity61380.4040.52 (0.12,2.19)Anti-HBc positivity1620.1670.23 (0.03,1.84)Maternal HBeAg positivity2290.6501.43 (0.28,7.23)Maternal HBV DNA load 100 IU/mL648 0.020 5.25 (1.26,21.83) Open in a separate windows 1stand for finished two-dose or three-dose injection according to vaccination schedule. The viral load of mothers was associated with occult contamination (Table 4, em P /em ?=?0.020); the percentage of maternal viral loads 100 IU/mL (66.66%) in OBI-positive infants was significantly higher than that of OBI-negative infants (27.59%, em P /em ?=?0.020). Other serologic markers of mothers or infants were not significantly different between OBI-positive and -unfavorable infant groups. Of note, none of the pregnant mothers had detectable HCV antibodies. Three of the pregnant mothers.