(P34) Antibody responses to PCV-10 and Streptococcus pneumoniae nasal carriage in HIV infected children in Ethiopia
Mahlet Lemma [1,2,3], Yonas Bekele , Stefan Petkov , Rawleigh Howe , Francesca Chiodi 
. Department of Microbiology, Tumor and Cell Biology at Biomedicum, Karolinska Institutet, Stockholm, Sweden . Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia . Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
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.
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).
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.
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.