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Seronegativation in Early Treated HIV-Infected Infants: Frequency and Potential Implications on Care and Follow-up in a Resource-Limited Country

2011; Lippincott Williams & Wilkins; Volume: 58; Issue: 2 Linguagem: Inglês

10.1097/qai.0b013e31822d49f0

1944-7884

Anfumbom Kfutwah, Mathurin Cyrille Tejiokem, Francis Ndongo Ateba, Jean Audrey Ndongo, Calixte Ida Penda, Paul Alain Tagnouokam‐Ngoupo, Patrice Tchendjou, Gisèle Chewa, P. Boisier, Christine Rouzioux, Josiane Warszawski, Albert Faye,

HIV/AIDS drug development and treatment

To the Editors: INTRODUCTION Based on the high mortality rates observed in HIV-infected children during the first 2 years of life, the World Health Organization (WHO) recommends early diagnosis and early initiation of highly active antiretroviral therapy (HAART).1 A pediatric study (ANRS 12140-Pediacam) was launched in Cameroon in November 2007 with the aim to evaluate the feasibility and efficacy, in routine practice, of early HAART offered systematically to HIV-infected infants before 7 months of age. One of the Pediacam, HIV-infected early treated infant presenting with fever was examined, in an outpatient clinic, by a medical practitioner not informed of the therapeutic management and follow-up of the child. Considering the mother's HIV status and the fact that the child was 15 months old, the practitioner after emergency handling opted for a serological test to confirm the child's HIV status. The infant's HIV rological test result was negative, a situation that subsequently created some misapprehensions. We report this case and others in the Pediacam study, with an objective to assess the frequency of seronegativity among HIV-infected infants who were treated early with HAART. METHODS The ANRS-Pediacam study is coordinated by the Centre Pasteur of Cameroon and ongoing in 3 referral hospitals: the Mother and Child Centre of the Chantal Biya Foundation and the Essos Hospital Centre both in Yaounde and the Laquintinie Hospital in Douala. Four groups of children participate in this study, and among them, 3 groups are recruited from birth (or before the eighth day of life) and followed up according to the National Expanded Programme on Immunization schedule. These groups comprise HIV-infected children diagnosed at 6 weeks, HIV uninfected children born to HIV-positive mothers, and HIV-negative children born to HIV-negative mothers. The fourth group comprises HIV-infected children not followed up from birth but diagnosed before 7 months. Early HIV diagnosis was performed by real-time HIV-RNA PCR (Biocentric HIV Viral Load; Biocentric, Bandol, France) using an in-house protocol (ANRS AC 11/12 working group).2 A positive or indeterminate test result was confirmed with another sample. Systematic early initiation of HAART was offered to all HIV-infected infants identified. Consent from the infants' parents was obtained before inclusion. Ethical clearance was obtained from the Cameroon National Ethics Committee. HIV-infected children were tested at 15 months or above for the assessment of HIV circulating antibodies. This serological testing comprises a fourth-generation test (AxSYM HIV Ag/Ab Combo assay; Abbott Diagnostics, Wiesbaden, Germany) as the first test in the algorithm. Initial sample/cut-off values >1.00 are reactive, whereas values 0.90 to ≤1.00 are considered gray zone values. A result of <0.90 is considered negative, and no further testing is required. Therefore, in this study, seronegativity was defined as HIV-infected infants, aged 15 months or older, with AxSYM blood sample/cut-off values <0.90. Seronegative samples were also tested using the “2 rapid tests” algorithm recommended by the WHO in economic restraint countries.3 HIV-1 Western blot (Bio-Rad, Marnes-la-Coquette, France) was also used to characterize these samples. Repeated HIV seronegative samples were confirmed for HIV infections by HIV1-DNA PCR (Biocentric). RESULTS Among the 57 HIV-infected infants who initiated HAART at a median age of 3.7 months (interquartile range: 3.1-5.9) and tested serologically at a median age of 19.4 months (interquartile range: 18.1-21.9), 15 (26.3%, 95% confidence interval: 15.5 to 39.7) were seronegative with AxSYM and 6 (10.3%) were indeterminate for HIV antibody analysis. Testing these 15 seronegative samples with the 2 rapid tests algorithm, it was observed that in concordance with AxSYM, 6 of 15 infants were negative with both rapid tests used, and none of the samples could be concluded positive by Western blotting (Table 1). Others had equivocal results with at least one of the 2 rapid tests being negative (data not shown). In Table 1, we present the 6 children who were AxSYM negative and 2 rapid test negative. Serotyping of these samples before first HIV PCR diagnosis revealed that they were all of HIV-1 group M serotype. Results of viral load assays performed while children received HAART and a few months (mean 3.3 months) before serological testing showed that 5 of 6 infants had very low to undetectable viral loads ( 99.9%, respectively) has encouraged its widespread use in routine HIV diagnosis.8 In simulation of what could be obtained, if these children are consulted in a remote health facility, we diagnosed 6 unequivocal seronegative samples using the 2 rapid tests algorithm.3 Determine and Oraquick rapid tests used in this study meet the WHO standards of sensitivity and specificity.9,10. All samples in this study were serotyped as HIV-1 group M, that is, there were no divergent HIV strains that could lead to possible misdiagnosis. The viral loads of the 2 cases of HIV-positive seronegative infants already described4,5 were >6 and 5.8 log10 copies per milliliter at the age of 2 and 4 months, respectively. This profile combining high HIV viral load and seronegativity seem to be in agreement with only 1 infant in our study (infant 4: 18.8 months old, viral load of 5.9 log10 copies/mL). However, it should be noted that, in this study, viral load analysis was done on an average of 3 months before serological analysis and therefore does not exclude changes in viral load before serodiagnosis because the child is on HAART. Generally, seronegativity has been observed in patients presenting with symptoms that meet AIDS defining cases. Conversely, low/undetectable viral load and seronegativity observed by Luzuriaga et al6 are understandably in line with 5 of 6 seronegative infants in this study. In both studies, the role of HAART in drastically reducing the viral loads cannot be underestimated. Furthermore, some studies in adults have shown HIV patients treated early in the course of their infections with ARV therapy that became seronegative,11 a situation similar to ours, albeit in adults. We could postulate that the early exposure of these infants to HAART led to a rapid virological suppression and consequently the lack of viral antigen to illicit immune response. Similarities have been observed in the kinetics of plasma HIV-1-specific antibody clearance in infants who received early therapy and uninfected infants born to HIV-1-seropositive women, suggesting that these infants did not actively generate HIV-1-specific antibodies.4 Other immunological tests, especially antibody production assays and kinetics, in these infants could further elucidate this observation in our study sites. Western blotting showed that just 1 infant had an envelope glycoprotein band (gp160), whereas others had only 1 or 2 bands representing the internal proteins. The nonreactivity to serological tests could be due to the fact that these children did not have the circulating envelope proteins commonly used in serological tests such as gp41.5 Other studies have shown that the nonexpression of envelope glycoprotein in some patients could lead to the seronegativity observed in some rapid tests.12 Children in this study are undoubtedly infected with HIV as shown by HIV-RNA PCRs carried out before treatment and the HIV-DNA PCRs carried out concomitantly with HIV-specific antibody testing. Our observation of HIV seronegativation in 26.3% (15 of 57) of HIV-infected infants suggests that this phenomenon is not uncommon. This has been heightened by our experience of a known HIV-positive child on HAART that was tested seronegative in another hospital department and the ensuing misapprehensions that were generated. If caution is not exercised, the interpretation of such serological tests could be misleading in resource limited settings like ours. Importantly, in settings where virological tests are not available, WHO recommends an early presumptive therapy in infants based on clinical findings and a positive serological test with a serological confirmation of HIV infection after 15 months of age.1 Our data suggest that, this serological confirmation could be inappropriate even when performed above 15 months of age and could lead to inappropriate treatment interruptions in HIV-infected infants receiving early treatment. Anfumbom K. W. Kfutwah, PhD* Mathurin Cyrille Tejiokem, MD, MPH†,‡ Francis N. Ateba, MD§ Jean Audrey Ndongo, MD§ Ida Calixte Penda, MD‖,¶ Paul Alain T. Ngoupo, MSc* Patrice Tchendjou, MD, MPH† Gisele Chewa, MD# Pascal Boisier, MD, PhD† Christine Rouzioux, PharmD, PhD** Josiane Warszawski, MD, PhD††,‡‡ Albert Faye, MD, PhD§§,‖‖ ANRS 12140-Pediacam Study Group *Service de Virologie, Centre Pasteur du Cameroun, Membre du Réseau International des Instituts Pasteur, Yaoundé, Cameroun †Service d'Epidémiologie et de Santé Publique, Centre Pasteur du Cameroun, Membre du Réseau International des Instituts Pasteur, Yaoundé, Cameroun ‡Université Paris 11, Faculté de Médecine Paris-Sud, Paris, France §Centre Mère et Enfant de la Fondation Chantal Biya, Hôpital de Jour, Centre de Traitement Agrée Yaoundé, Cameroun ‖Hôpital de Jour, Hôpital Laquintinie, Douala, Cameroun ¶Université de Douala, Faculté de Médecine Douala, Cameroun #Service de Pédiatrie, Centre Hospitalier d'Essos, Yaoundé, Cameroun **Laboratoire de Virologie, Hôpital Necker, Paris, France and EA 3620 Université Paris 5 René Descartes, UFR de Médecine, Paris, France ††Equipe 4 (VIH et IST)—INSERM U1018 (CESP), Le Kremlin Bicêtre, France ‡‡Assistance Publique des Hôpitaux de Paris, Service d'Epidémiologie et de Santé Publique, Hôpital de Bicêtre, Paris, France §§Assistance Publique des Hôpitaux de Paris, Service de Pédiatrie Générale, Hôpital Robert Debré, Paris, France ‖‖Université Paris 7 Denis Diderot, Paris, France UFR de Médecine, Paris, France. ACKNOWLEDGMENTS The authors are grateful to all the members of the Pediacam study group for their untiring commitment to the success of this study. We thank all the children and their parents/guardians for accepting to be part of this great endeavor. We also thank Jean-Marc Reynes for useful discussions.