Low levels of HIV-1 plasma viral load in patients infected with HIV-1 subtype b and advanced immunosuppression.
OBJECTIVE
Some HIV-1 infected patients show low levels of viraemia despite having advanced immunosuppression. Cases with falsely undetectable viraemia by conventional PCR have been reported when patients were infected with non-B subtypes. The aim of this study was to investigate whether this immunovirological discordance can be due to the presence of HIV-1 non-B subtypes, and whether a modified PCR procedure can yield different HIV viraemia values in these cases.


METHODS
Fifteen HIV-infected patients either naive for antiretroviral drugs or under treatment, with HIV plasma viraemia below 1000 copies/mm(3)and CD4+ cell counts lesser than 500 or 300 cells/mm(3), respectively, were included. Serotyping, genotyping and HIV plasmatic viraemia determinations were performed in all individuals.


RESULTS
In five out of six treatment-naive patients the virus was categorized as non-B subtype by serotyping, although only one case was confirmed by genotyping as HIV-2. Eight out of nine patients under antiretroviral therapy were subtype B carriers by serotyping and confirmed by genotyping. The remaining patient was determined as a subtype A carrier by both procedures. A modified PCR procedure (Amplicor HIV Monitor Test version 1.5) did not yield higher viral load levels than the former version.


CONCLUSIONS
The presence of HIV-1 subtypes non-B can explain a minority of cases of this immunovirological discordance, but in most of them the reason is still unknown. Likewise, a PCR procedure adapted for detecting HIV-1 non-B subtypes fails to find higher plasma viraemia in patients with such a discordance.
Department of Internal Medicine, Virgen del Rocio University Hospital, Seville, Spain.
R
R
de la Rosa
M
M
Leal
J A
JA
Pineda
U
U
Dietrich
J
J
Delgado
J
J
Macías
A
A
Rubio
A
A
Sánchez-Quijano
E
E
Lissen
D000328:Adult; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000276:immunology / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000502:physiology; D006801:Humans; D007108:Immune Tolerance; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D012703:Serotyping; D019562:Viral Load; D014766:Viremia / Q000175:diagnosis / Q000276:immunology / Q000821:virology*