(P34) Antibody responses to PCV-10 and Streptococcus pneumoniae nasal carriage in HIV infected children in Ethiopia

Författare/Medförfattare

Mahlet Lemma [1,2,3], Yonas Bekele [1], Stefan Petkov [1], Rawleigh Howe [2], Francesca Chiodi [1]

Affiliates

[1]. Department of Microbiology, Tumor and Cell Biology at Biomedicum, Karolinska Institutet, Stockholm, Sweden [2]. Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia [3]. Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia

Abstract

Background:
WHO recently reported 515 000 deaths related to Streptococcus pneumoniae diseases in 2015 in children under 5 years of age. Additionally, 23 300 mortality cases were recorded globally in HIV infected children. A ten valent pneumococcal vaccine (PCV-10) was incorporated in 2011 in the Ethiopian immunization program and administered in 3 primary doses with no booster (3+0) starting at 6 weeks of age. No previous studies have addressed the responses to PCV-10 in Ethiopian children. We aimed at measuring PCV-10 responses in treated HIV-infected children and age-matched controls; moreover, the nasal carriage of S. pneumoniae was determined in both groups.

Methods:
HIV-infected children (n=50; age range 48-70 months) receiving ART and vaccinated with PCV-10 were recruited from ALERT and Zewditu Memorial hospitals in Addis Ababa. Age-matched non-HIV infected controls (, n=59; age range 56-63 months) with a similar vaccination status were enrolled from Woreda 03 Health center. Vaccination history was confirmed using a vaccination card record. Plasma and nasal swabs were collected and frozen until further analyses were conducted.
Serotype-specific IgG concentration against the serotypes incorporated in PCV-10 were measured in plasma by ELISA according to the WHO 2008 guidelines; the pneumococcal polysaccharide antigens were donated from SSI Diagnostica, Denmark. Culture-based identification of S. pneumoniae isolates was performed; DNA from the isolates was prepared and the Clinical Genomics SciLifelab performed whole genome sequencing (WGS).

Results:
No difference was detected in the proportion of HIV infected and control children presenting with an adequate (>1.32 g/ml) IgG concentration to vaccine serotypes. The largest proportion of controls and HIV infected responded to serotypes 1 (86% and 90%, respectively), 6B (68 and 66%), 14 (80 and 78%) and 19F (88 and 80%). Between 10-36% of the individuals in both groups showed a response to serotypes 4, 5, 7F and 18 C. Protective antibody levels to more than 5 serotypes were found in 62% of HIV infected and 60% of control children.
Pneumococcal carriage was detected in 52% of HIV infected children and 22% of controls. Among the isolates, 22 known and 11 novel sequence types were detected. Resistance genes to various antibiotics commonly used for the treatment of S.pneumoniae were detected in 5 isolates from controls and 8 isolates from HIV infected children.

Conclusions:
Comparable response to PCV-10 vaccination was detected in the infected and control group. S.pneumoniae carriage was more frequent in the HIV-infected children; WGS analysis will provide insights on the serotype of isolates obtained from nasal swabs of vaccinated children in Ethiopia, instructing the need for future vaccines.

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