Anti-R7V antibodies prevalence in HIV-infected patients followed in the ambulatory care centre of a university hospital, Cotonou, Benin

Abstract number: P1008

Lafia E., Houeze M., Zannou M., Bigot A., Guedou F., Anagonou S., Zohoun I.

Background and Objectives: A cellular epitope (R7V) is acquired by HIV when the virus is released by budding. All known variants present this epitope at their external membrane. Induced anti-R7V antibodies were described in vitro to neutralise cell infection. Research also indicated an association between the slow or non progressor status of HIV infected patients and presence of anti-R7V Ab.

Objectives were to determine the prevalence of anti-R7V Ab in HIV patients followed in the Ambulatory Care Centre at the University Hospital of Cotonou, Benin, and to assess the relationship of the Ab with the clinical status of patients.

Methods: A cross-sectional study was carried out from May to November 2007. 131 consenting patients were enrolled (average age was 36 and sex ratio=0.5). Blood specimens were drawn at the inclusion visit; serum sample was collected, coded and stored at -20^°C until anonymous testing. Samples were tested for anti-R7V by ELISA (Ivagen, Bernis, France). The statistical Pearson chi2 test was used to compare the presence of anti-R7V Ab and the variables, clinical status of the patients and treatment.

Results: For 114 patients among the 131, date of HIV diagnosis ranged from February 1999 to August 2007. Mode of contamination was unknown for all patients.

Anti-R7V Ab were found in 90.4% of patients HIV-diagnosed in 2006, in comparison of whose diagnosed in 2004 (43.4%), p<0.01. The prevalence of Ab was also highly significant (p<0.01) in the group of 60 asymptomatic patients (83.3%) versus the group of 71 symptomatic patients (59.1%). Less anti-R7V positive results were observed for patients under ARV treatment (53.2%) than for naive patients (85.5%), p<0.001. No difference was shown between immunocompromised patients (CD4 200 cells/mm³) and patients with no decline of CD4 (500 cells/mm³).

Conclusion: Prevalence study of the anti-R7V Ab in 131 HIV-infected patients showed: i) ARV treatment decreased the level of the Ab, as previously described; ii) it seems that there is no relationship with the immunocompromised status and decrease in the presence of Ab; iii) anti-R7V Ab are highly more frequent in HIV patients always asymptomatic, for whom the detection of this humoral marker could be recommended.

A follow-up of the patients who tested positive for anti-R7V Ab will enable to determine whether the presence of Ab is predictive of a slower progression, or non progression toward AIDS.