Abstract:
The most commonly used markers for monitoring efficacy of anti-retroviral therapy in
Human Immunodeficiency Virus (HIV) infected individuals are the viral load and CD4+
cell counts. Viral load monitoring is limited in resource limited countries due to its high
cost, therefore leaving the use of CD4+ T cell counts as the only alternative for
evaluating HIV infected individuals. CD4+ cell counts is an unreliable predictor of
disease progression even though it is cheaper and most readily available in these
settings. There is therefore a need to develop more sensitive and less costly alternative
techniques for the detection of treatment failure which can be of utmost importance in
these resource limited settings. This study sought to evaluate the feasibility of using
Dipeptidyl peptidase IV (DPPIV) in plasma as a novel marker for the clinical evaluation
of efficacy of treatment in young HIV infected individuals. DPPIV is an enzyme that
cleaves N-terminal dipeptides next to an alanine or proline residues. Blood samples were
collected from HIV positive young individuals (n=76) before and after initiation of ART,
then assessed for HIV RNA (viral load), CD4+ T cell count and DPPIV levels. Roche
Amplicor HIV-1 Monitor Test kit was used to analyse viral load levels while the BD
FACS Calibur flowcytometer was used to analyse the levels of CD 4+ T cell counts with
the Human DPPIV Quantikine ELISA kit (R&D Systems, Minneapolis MN) used to
analyse DPPIV levels. The levels of plasma DPPIV increased significantly in study
participants after ART initiation (p = 0.017), while the levels of viral load declined after
ART initiation with an increase in CD4+ cell counts. There was a weak correlation
(r=0.26) between the change in DPPIV after ART to the change in viral load after ART
while there was a no correlation (r=0.14) between the change in DPPIV levels after ART
to the the change in CD 4+ cell counts after ART. There was no statistically significant
difference in DPPIV (p=0.7460), viral load (p=0.9875), and CD 4+ cell counts (p=
0.548) with gender. The findings further showed a significant inverse relationship
between the DPPIV levels (p=0.0017 increase after ART) and HIV viral load levels (p=0.0001 decrease after ART) and the presence of a direct relationship of DPPIV levels
(p=0.0017 increase after ART) to the CD4+ Cell counts levels (p=0.0001 increase after
ART). The latter suggesting a potential for DPPIV use as a more cost effective and a
sensitive alternate surrogate marker for the evaluation of HIV disease progression in
young individuals on HIV treatment.