OBJECTIVETo investigate the blood test patterns for blood donors after nucleic acid detection in blood center.

METHODSThe collected blood samples after voluntary blood donors first were detected by conventional ELISA, then 31981 negative samples were detected via HBV/HCV/HIV combined nucleic acid test of 6 mixed samples(22716 cases) or single samples(9265 cases) by means of Roche cobas s201 instrument. The combined detection method as follows: the blood samples were assayed by conventional nucleic acid test of 6 mixed samples, at same time, 6 mixed samples were treated with polyethylene glycol precipitation method to concentrate the virus, then the nucleic acid test of blood samples was performed; the single detection method as follows: firstly the conventional nucleic acid test of single sample was performed, then the positive reactive samples after re-examination were 6-fold diluted to simulate the nucleic acid test of 6-mixed samples. The positive rate of positive samples detected by combined nucleic acid test, positive samples detected by nucleic acid test of mixed virus concentration and positive samples detected by single nucleic acid test was statistically analyzed. In addition, for HBVpersons the serological test yet should be performed.

RESULTSIn 22 716 samples detected by nucleic acid test of 6 mixed samples (MP-6-NAT) , 9 cases were HBV(0.40‰, 9/22716); at same time, the detection of same samples by nucleic acid test of mixed sample virus concentration showed 29 cases of HBV(1.28‰, 29/22716). In 9265 samples detected by single nucleic acid test(ID-NAT) 12 cases showed HBV(1.30‰, 12/9265), meanwhile the detection of these 12 samples with HBVby 6-fold dilution for virus concentration found only 4 samples with HBV. In serological qualified samples, ID-NAT unqualified rate was 1.28‰, which was higher than that of MP-6-NAT(0.4‰) (χ=8.11, P<0.05); but there was no statistical difference between unqualified rate of ID-NAT and MP-6-NAT(1.3‰ vs 1.28‰)(χ=0.00, P>0.05). In 41 samples with HBsAgHBV DNAdetected by ELISA, 36 samples were confirmed to be occult HBV infective(OBI) by HBsAb, HBcAb test of ELISA; out of these 41 samples, 33 samples showed HBcAb(91.66% of OBI), 5 might be HBV "window period" infective, moreover the HCV RNA and HIV RNA positive samples were not found.

CONCLUSIONTo avoid the missdiagnosis of donors with low level of virus, the nucleic acid test must be carried out after virus concentration of mixed samples when the blood test pattern of donors is nucleic acid test of mixed samples, otherwise the single nucleic acid test must be performed to obtain more high detected rate of virus nucleic acid. The HBcAb serologic test and physical examination of donors before blood donation must be enhanced on basis of serological test of HBsAg; for high risk people, the persuading no blood donation is simplest pattern.