Abstract
INTRODUCTION Differentiating between HIV-1 and HIV-2 infection is the first step to understanding HIV transmission, epidemiology and pathogenesis in geographical areas where both viruses circulate. In Cuba, positive results in mixed HIV-1/2 screening assays are confirmed by HIV-1 Western blot. Indeterminate results constitute the main limitation of this test and HIV-2 infection is among their possible causes; hence the importance of second-stage screening and confirmatory tests for HIV-2 infection. OBJECTIVE Investigate the contribution of HIV-2 antibodies to negative or indeterminate HIV-1 Western blot results in serum samples from 2005 through 2008 in Cuba. METHODS HIV-2 reactivity was studied using the ELISA DAVIH-VIH-2 diagnostic kit (Cuba) in 1723 serum samples with negative or indeterminate results for HIV-1 Western blot from January 2005 through December 2008. Duplicate sera reactive by ELISA were confirmed by HIV-2 Western blot, results interpreted according to WHO criteria. The epidemiological interview established by Cuba's National Program for Prevention and Control Sexually-Transmitted Diseases and HIV/AIDS was applied to HIV-2 Western blot-positive patients. RESULTS Among all sera studied, HIV-2 ELISA identified 12 reactive serum samples (0.70%) and 1711 non-reactive (99.30%). Western blot analysis of the 12 ELISA-reactive samples confirmed two positive samples (16.67%), 4 negative (33.33%) and 6 indeterminate (50%). Positive samples reacted against the p16, p26, gp36, p53, p56, p68 and gp105 proteins. All 12 ELISA-reactive samples belonged to the HIV-1 Western blot indeterminate group. The two HIV-2-positive samples showed well defined reactivity to gp160, p53, p55 and p34 of HIV-1. HIV-1 seroconversion was observed in all 10 remaining samples during serological followup. CONCLUSIONS Two new HIV-2 seropositive cases were diagnosed using DAVIH-VIH-2 and HIV-2 Western blot in indeterminate HIV-1 Western blot samples. Results support the recommendation that HIV-2 Western blot be included in the diagnostic algorithm for HIV-1/2 to followup negative or indeterminate HIV-1 Western blot results. KEYWORDS Diagnosis, laboratory techniques and procedures, antibodies, HIV-2, Western blot, enzyme-linked immunosorbent assay, algorithm, Cuba.
Highlights
INTRODUCTION Differentiating between HIV1 and HIV-2 infection is the first step to understanding HIV transmission, epidemiology and pathogenesis in geographical areas where both viruses circulate
Results support the recommendation that HIV-2 Western blot be included in the diagnostic algorithm for HIV-1/2 to followup negative or indeterminate HIV-1 Western blot results
Reported non-reactive tive samples are analyzed with the HIV-2 enzyme-linked immunosorbent assays (ELISA), DAVIH–VIH-2 (DAVIH Laboratories, Cuba); samples that are nonreactive by ELISA that were indeterminate by DAVIH–blot for HIV-1 lead to serological patient followup for at least one year
Summary
1 and HIV-2 infection is the first step to understanding HIV transmission, epidemiology and pathogenesis in geographical areas where both viruses circulate. In Cuba, positive results in mixed HIV-1/2 screening assays are confirmed by HIV-1 Western blot. Indeterminate results constitute the main limitation of this test and HIV-2 infection is among their possible causes; the importance of second-stage screening and confirmatory tests for HIV-2 infection. Infections HIV-2 and HIV-1 cause acquired immunodeficiency syndrome (AIDS). Clinical symptoms are similar in both cases, HIV-2 is less pathogenic; the latency period is longer than ten years; and case-fatality is estimated to be one half to one third that of HIV-1, possibly due to lower viral load.[1,2]. Most HIV infections are caused by HIV-1. HIV-2, initially restricted to West Africa,[3] has spread to all continents.[4,5,6] Most cases diagnosed outside western African countries are epidemiologically linked to persons in that region or native to it and have been found mainly in Portugal, France, Spain and southeast India.[7,8,9,10] Less frequently, cases have been reported in other European countries and in the Americas and Asia.[11,12,13]
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