Comparison of HIV positive results between ELISA screening and western blot test

Objective To compare human immunodeficiency virus(HIV)positive results between enzyme linked immunosorbent assay(ELISA)/Electro selenium screening and western blot(WB)test and to study the relationship between the results of screening and WB among the examinees in Putuo district of Zhoushan city,Zhejiang province.Methods Using methods described in the“National Guideline for Detection of HIV/acquired immunodeficiency syndrome(AIDS)”,185 positive specimens ascertained by HIV antibody screening were confirmed by WB test.Results Of all the samples,160(86.49%) were confirmed to be positive,13(7.03%) samples negative and 12(6.49%) samples uncertain by WB test.The positive coincidence rates of ELISA/Electro selenium method with WB were 88.89%and 89.89%(P>0.05).The mean value of signal to cutoff(S/c.o)of WB confirmation test were 15.76±7.42,5.48±2.17 and 6.83±3.06 for positive,negative and uncertain samples,respectively(P<0.05).For the 11 samples with the S/c.o values of equal to or more than 1 and less than 6,the positive coincidence rate with WB was 18.18%;for 17 samples with the S/c.o value of equal to or more than 6 and less than 10,the positive coincidence rate was 70.59%;and for 151 samples with the S/c.o value of more than 10,the positive coincidence rate was 96.69%.The appearance rates of gp¹⁶⁰,gp¹²⁰,gp⁴¹,p⁶⁶,p⁵¹,p⁵⁵,p²⁴ reactive bands were all over 95%in WB confirmed HIV-1 antibody positive samples.Conclusion There are some false positive results in HIV screening test,suggesting the final HIV antibody test result must be confirmed by WB test,but WB test also has limitation for uncertain samples.