A peptide enzyme linked immunosorbent assay (ELISA) for the detection of human immunodeficiency virus type-2 (HIV-2) antibodies: an evaluation on polymerase chain reaction (PCR) confirmed samples.
BACKGROUND
HIV-1 and HIV-2 infections differ in prognosis, and may also require different prevention and/or treatment approaches. Thus, estimating the true prevalence of HIV-1 and HIV-2 infections, as well as co-infections, is a critical step in controlling the disease. There are a few commercial ELISA and immunoblot kits, which can differentiate between HIV-1 and HIV-2 infections. However, some of these assays overestimate the prevalence of dual infection. Hence, it is necessary to develop assays capable of discriminating between the two infections.


OBJECTIVE
To develop a synthetic HIV-2 env based peptide ELISA for the detection of HIV-2 specific antibodies and evaluate its performance on samples from HIV positive individuals previously tested by HIV-1 and HIV-2 PCR and HIV seronegative individuals.


METHODS
We studied 45 HIV seronegative and 63 HIV infected individuals, including 30 HIV-1 PCR and immunoblot positives, 19 HIV-2 PCR and immunoblot positives, five HIV-1 and two PCR and dual immunoblot positives, two PCR negative but positive for HIV-2 by immunoblot and seven dual immunoblot positives who were only positive for HIV-1 by PCR.


RESULTS
All 24 HIV-2 PCR positive samples tested were positive by the peptide assay. Among 30 HIV-1 PCR and immunoblot positive samples, only one (3.3%) showed an absorbance value above the cut off level. The seven dual positive samples by immunoblot (only positive for HIV-1 by PCR) were negative by the HIV-2 peptide ELISA. There was a 100% concordance between HIV-2 PCR and peptide ELISA. The sensitivity, specificity, and the likelihood ratio for the peptide ELISA were 100,94.9, and 19.5, respectively when compared against the PCR findings.


CONCLUSIONS
This ELISA, using a specific immunodominant epitope (11 amino acids) from the transmembrane (gp36) portion of the HIV-2 envelope glycoprotein showed a high concordance with PCR findings. This can be considered as a highly sensitive, specific and economically feasible assay for the discrimination of HIV-1 and HIV-2, and may serve as an alternative to HIV-2 PCR in epidemiological studies.
Kannangai
R
R
Department of Clinical Virology, Christian Medical College Hospital, 632 004, Vellore, India.
Ramalingam
S
S
Prakash
K J
KJ
Abraham
O C
OC
George
R
R
Castillo
R C
RC
Schwartz
D H
DH
Jesudason
M V
MV
Sridharan
G
G
D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D015686:Gene Products, env / Q000276:immunology; D015483:HIV Antibodies / Q000097:blood* / Q000276:immunology; D015658:HIV Infections / Q000097:blood / Q000276:immunology / Q000821:virology*; D015497:HIV-1 / Q000235:genetics; D015498:HIV-2 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D010455:Peptides / Q000276:immunology; D016133:Polymerase Chain Reaction / Q000379:methods
D015686:Gene Products, env; D015483:HIV Antibodies; D010455:Peptides