The existence of an antisense Open Reading Frame (ORF) that encodes a putative AntiSense
Protein (ASP) on the proviral genome of Human Immunodeficiency Virus type 1 (HIV-1) was a source of debate for 30 years. During the last years, some progresses have been made to characterize the cellular immune response against ASP in HIV-1 seropositive patients. However, no tools were available for the detection of
antibodies to ASP in the plasma of HIV-1-infected patients during the natural course of the
infection. The aim of our study was to develop a
Luciferase Immuno-Precipitation System (LIPS) to monitor the quantitative detection of ASP-specific
antibodies in the plasma of HIV-1-infected patients [antiretroviral
therapy (ART) naive-patients, patients under ART and HIV-1 controllers], patients who discontinued antiretroviral drugs (ARV). We further used this approach to delineate the
epitopes of ASP targeted by
antibodies.
Antibodies directed against ASP were detected in 3 out of 19 patients who discontinued ARV (15%) and in 1 out of 10 ART-naive patients (10%), but were neither detected in HIV-1 infected patients under ART nor in HIV-1 controllers. Individual variations in levels of ASP-specific
antibodies were detected overtime. Both the conserved prolin-rich motif and the core 60-189 region of ASP were found to be essential for antibody recognition in the four patients tested positive for anti-ASP
antibodies, who were all untreated at the time of sampling. Moreover, for two of these patients, increased levels of ASP-specific
antibodies were observed concomitantly to
viremia declines. Overall, our method may represent a useful tool to detect a humoral response to ASP in HIV-1-infected patients, which allowed us to confirm the expression of ASP during the course of HIV-1
infection. Further studies will be needed to fully characterize the humoral response to ASP in HIV-1-infected patients.