Comparative evaluation of an immunofluorescent antibody test, enzyme immunoassay and western blot for the detection of HIV-1 antibody

Western blot-indeterminate results in Nigerian patients HIV serodiagnosis: the clinical and public health implication

The clinical and public health implication of HIV Western blot (WB) indeterminate results is yet to be appraised in sub-Saharan Africa, including Nigeria. Using HIV Tri Line Test enzyme-linked immunosorbent assay (ELISA), 1286 patients (600 males and 686 females; age range, 5-60 years) with symptoms suggestive of HIV infection were screened. A total of 1020 (79.3%, 95% confidence interval [CI] 76.8-81.5) of the patients comprising of 514 (85.7%) males and 506 (73.8%) females were HIV seropositive and the difference was statistical significantly (chi(2) = 5.72, df = 1, p < 0.05). Western blot analysis of sera from the 1020 HIV-seropositive individuals using the BIO-RAD NEW LAV-BLOT I specifying World Health Organization (WHO) interpretive criteria, confirmed the HIV serostatus of 815 (79.9%, 95% CI, 77.4-82.4) of them with 205 (20.1%, 95% CI, 17.6-22.6) individuals having indeterminate results consisting of either; 1 env +/- gag +/- pol, gag + pol, gag only or pol only. Of these, 102 (19.8%) were males and 103 (20.4%) were females. Patients aged 11-20 years old recorded the highest percentage of indeterminate results (31.7%, 95% CI, 20.2-43.2) while those aged 21-30 years recorded the least (14.2%, 95% CI, 10.6-17.8) and the difference was statistically significant (chi(2) = 15.73, df = 5, p < 0.05). Result confirmed the limitation of Western blot assays in HIV confirmatory serodiagnosis. After obtaining HIV indeterminate Western blot result, clinicians should consider the total profile for the patient, reassess risk factors for HIV infection, perform a HIV retesting at 3-month intervals for 6 months or use an alternate HIV antibody confirmatory assay and running antibody tests for other human retroviruses.

Efficiency of indirect immunofluorescence assay as a confirmatory test for the diagnosis of human retrovirus infection (HIV-1 and HTLV-I/II) in different at risk populations

We compared the indirect immunofluorescence assay (IFA) with Western blot (Wb) as a confirmatory method to detect antibodies anti retrovirus (HIV-1 and HTLV-I/II). Positive and negative HIV-1 and HTLV-I/II serum samples from different risk populations were studied. Sensitivity, specificity, positive, negative predictive and kappa index values were assayed, to assess the IFA efficiency versus Wb. The following cell lines were used as a source of viral antigens: H9 ( HTLV-III b); MT-2 and MT-4 (persistently infected with HTLV-I) and MO-T (persistently infected with HTLV-II). Sensitivity and specificity rates for HIV-1 were 96.80% and 98.60% respectively, while predictive positive and negative values were 99.50% and 92.00% respectively. No differences were found in HIV IFA performance between the various populations studied. As for IFA HTLV system, the sensitivity and specificity values were 97.91% and 100% respectively with positive and negative predictive values of 100% and 97.92%. Moreover, the sensitivity of the IFA for HTLV-I/II proved to be higher when the samples were tested simultaneously against both antigens (HTLV-I-MT-2 and HTLV-II-MO-T). The overall IFA efficiency for HIV-1 and HTLV-I/II-MT-2 antibody detection probed to be very satisfactory with an excellent correlation with Wb (Kappa indexes 0. 93 and 0.98 respectively). These results confirmed that the IFA is a sensitive and specific alternative method for the confirmatory diagnosis of HIV-1 and HTLV-I/II infection in populations at different levels of risk to acquire the infection and suggest that IFA could be included in the serologic diagnostic algorithm.

Active replication of hepatitis B virus (HBV) in HIV type 1 and in HIV type 2 infected patients

To evaluate the effect of concurrent infection by HIV on HBV infection or immunity, we have studied a group of 66 HIV1+ symptomatic Caucasian patients and another of 38 African HIV2+ asymptomatic individuals, concerning their HBV status: serological markers of infection and presence of HBV-DNA in serum, the last taken as sign of hepatitis B virus active replication, were monitored. HIV+ groups were compared with seronegative controls, adequately matched for age, sex and ethnological background. HBV DNA was found in 7.6% of HIV1+ Caucasian patients and 3.2% of seronegative controls; in African HIV2+ individuals 2.6% were also HBV DNA+, a percentage close to that found in HIV2 seronegative controls (2.9%). No correlation was found between HIV infection and HBV active replication. Immunodepression that follows HIV infection over time may be compatible with a degree of T cell function capable of avoiding reinfection with or reactivation of HBV, even in symptomatic stages of acquired immunodeficiency syndrome. Our findings are relevant to the choice of preventive strategies in populations at risk for HIV and HBV infection.