Mutual effect of HIV/HCV Co-infection on laboratory diagnosis

Objective To investigate the mutual effect of HIV/HCV Co-infection on their testing or diagnosis.Methods The 300 participants of HIV infection were confirmed WB.All of them were tested for HCV antibody by EIA and CD_4/CD_8 count by cytoflowmetry; A subgroup of 197 participant were further tested for HCV viraemia by RT-PCR, HCV genotyping by RFLP and HIV load by NASBA. Testing results were compared between coinfection group and HIV monoinfection group and among different HCV genotype groups.Result Effect on HCV diagnosis: 8 of the 41 HCV antibody negative patients were HCV RNA positive , and false negative rate is 19.5% . Statistical analysis shows that HCV RNA positive, 1b+2a genotype and genotype 1b were independently associated with higher A and S/CO value of HCV EIA testing. Effect on HIV diagnosis: HIV ELISA A value 3 of coinfection group and HIV monoinfected group were 4/265 and 5/41 respectively (P0.01) ; Adjusting for CD4 and comparing the 77 HIV WB band result, the coinfected patients has statistically more P55 band presence (P0.01),while the difference on other band was not found.Conclusion The false HCV Ab negative result due to the immune dysfunction by HIV was comparably very high in our studied HIV infected population. HCV RNA qualitive testing was highly recommended for this population. HIV/HCV coinfection may impact the humoral immune response and increase the HIV antibody titer, which lead to the higher A value of HIV ELISA and more P55 band presence. HCV RNA positive,1b+2a genotype and genotype 1b are independent determinant for S/CO value of HCV EIA testing.