ABSTRACT
<p><b>OBJECTIVE</b>To investigate the characteristics of seroconversion of HBV NAT screening-positive crowd from blood donors in Dongguan city and provide reference for the safety of blood transfusion and disease prevention.</p><p><b>METHODS</b>With retrospective survey, Nucleic acid testing (NAT) was used to analyze 28800 HBsAg-negative samples by ELISA from blood donors in Dongguan city from August, 2006 to August, 2007 with Roche Cobas AmpliScreen systems; and follow-up research including NAT for HBV-DNA, ELISA for HBsAg and multiple factors analysis for HBV infection was carried out on HBV NAT screening-positive crowd.</p><p><b>RESULTS</b>10 positive pooling were screened from 28800 samples; after further detection, 2 of these positive pooling were HBV-DNA negative and 8 HBV-DNA positive samples were found.The 10-week follow-up research on these 8 blood donors showed that 6 were HBV-DNA positive and HBsAg-negative at 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks respectively, 1 was not HBsAg positive until 2 weeks and was positive on follow-up, and considered in "window period", 1 was HBV-DNA negative, HBsAg-negative on follow-up. Of these 8,7 were not only migrant laborers with poor condition of work, life and health but also in high risk of secondary infection for HBV, in addition they had little idea of therapy or prevention measures of HBV infection and the other 1 was HBV-DNA negative, HBsAg-negative on follow-up, who was in better condition than the above 7 donors.</p><p><b>CONCLUSION</b>NAT is more sensitive than ELISA in screening HBV, but the probability of being false positive of NAT can not be ignored at the same time. On the hand, only screening HBsAg for HBV is relative limitation in high infection region of China. Some factors would have effect on the serum conversion of blood donors including the quality of work and life, therapy or prevention measures.</p>