Immunofluorescence assay in India for confirmation of HIV-1 infection using a T-cell line infected with defective HIV-1.
BACKGROUND
In India, the enzyme immunoassay (EIA)/rapid test is used for screening and confirmatory antibody testing of HIV infection, and all HIV reactive samples are further confirmed by two other rapid tests working on different principles; however, Western blotting (WB) and immunofluorescence (IF) assays are not routinely performed in this country.


METHODS
A total of 2104 sera from Indian subjects were tested for the presence of HIV-1 antibody using EIA/rapid tests, according to the guidelines of the National AIDS Control Organization of India, and were also subjected to IF test using L-2 cells persistently infected with defective HIV-1. WB and a nested reverse transcriptase polymerase chain reaction (RT-PCR) were performed on discrepant samples.


RESULTS
IF results were 100% concordant with EIA/rapid tests for 212 HIV-1-positive samples and 1889 HIV-1-negative samples. Interestingly, three (0.14%) samples negative by EIA/rapid tests were weakly or moderately positive (1+/2+) by IF test. All three of these samples were confirmed to be negative by WB (reactive with Gag/Pol, but not with Env), but positive by RT-PCR with primers targeting the C2-V5 fragment of the env gene. These three samples were from individuals who voluntarily reported for HIV testing because of high-risk practices, and they may have been at an early stage of HIV infection.


CONCLUSIONS
These results confirm that the IF test using L-2 cells is a sensitive and specific alternative method for confirmation of HIV-1 infection and could be included in the diagnostic algorithm in reference laboratories in developing countries.
Department of Virology, Research Institute for Microbial Diseases, Osaka University, 3-1, Yamadaoka, Suita, Osaka 565-0871, Japan.
Manju
M
Bala
Juan F
JF
Arias
Monorama
M
Deb
Kazuyoshi
K
Ikuta
D015492:AIDS Serodiagnosis / Q000379:methods*; D015153:Blotting, Western; D002460:Cell Line; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D015483:HIV Antibodies / Q000097:blood*; D015488:HIV Antigens / Q000276:immunology*; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007194:India; D008297:Male; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology / Q000821:virology*
D015483:HIV Antibodies; D015488:HIV Antigens; D011933:Reagent Kits, Diagnostic