Jacent Nassuuna Poster 2023

Ms Jacent Nassuuna

MRC/UVRI and LSHTM Uganda Research Unit, Uganda

Effect of Intensive Treatment For Schistosomiasis, and of The Rural-Urban Environment, on Vaccine-Specific Immune Responses in Ugandan Adolescents

Poster Abstract

Gyaviira Nkurunungi1,2, Ludoviko Zirimenya1,4, Jacent Nassuuna1, Agnes Natukunda1, Emily L Webb3, Alison M Elliott1,4

  1. Immunomodulation and Vaccines Programme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda.
  2. Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom.
  3. MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom.
  4. Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, United Kingdom

Background. Rural-urban variations in vaccine-specific immune responses have been observed in tropical settings. Immunomodulating disease agents prevalent in rural settings, such as helminths, are implicated. We hypothesise that helminth infections contribute to impaired vaccine-specific responses and that their treatment could improve these responses.

Methods and analysis. We conducted a randomised trial of intensive versus standard praziquantel treatment amongst adolescents (9-17 years) from a rural Schistosoma mansoni-endemic Ugandan setting. Intensive arm participants received three praziquantel doses, each two weeks apart before vaccine administration while standard arm participants received praziquantel after vaccination. Participants in a separate, but linked, clinical trial from an established urban birth cohort in a lower-helminth exposure setting were enrolled for comparison. For both trials, five vaccines – BCG on day ‘zero’; yellow fever (YF-17D), oral typhoid (Ty21a), and human papillomavirus (HPV) vaccines at week 4; and HPV and tetanus/ diphtheria (Td) booster vaccine at week 28, were administered. Primary outcomes were BCG-specific interferon-γ ELISpot responses 8 weeks post-BCG vaccination and for other vaccines, antibody responses to key vaccine antigens 4 weeks post-YF-17D, Ty21a and HPV and 24 weeks post-Td vaccination. Schistosomiasis infection was determined retrospectively using the CAA assay.

Results. We enrolled 478 participants, 239 in each arm. Intensive treatment significantly reduced infection intensity by week 0 (median [IQR] CAA concentration, pg/ml, 29[7;226] vs 1527 [317;9105] in the standard arm), and significantly improved the week 8 BCG-specific IFN-γ response (p=0.027). There was no effect on YF-17D and Td-specific response. There were significant urban-rural differences in BCG-specific IFN- γ at week 0 (P=0.03) and week 52 (p=0.008) and tetanus-specific IgG (p=0.001) and YF-17D-specific neutralizing antibody titers (p=0.001). Data on responses to HPV and Ty21a vaccines are being generated.

Conclusion. Urban-rural differences were observed for all vaccines, but treating schistosomiasis improved responses only for BCG.

 

Biography

I am a Senior Laboratory Technologist with MRC/UVRI Uganda Research Unit and a Laboratory Manager for the Immunomodulation and Vaccine Programme laboratories under Prof. Alison Elliott. I have a Master of Science Degree in Immunology and Clinical Microbiology from Makerere University and a Bachelor of Science Degree from Mbarara University of Science and Technology. Since 2016, I have worked as a Senior Laboratory Technologist in the Programme and in 2017, I was promoted to the position of Laboratory Manager but still retained my role as senior technologist giving me the opportunity to still participate in different research projects. I have an interest in vaccine design and development and to contribute to this, I seek to understand factors that affect vaccine immunogenicity and efficacy in populations residing in low and middle-income countries, specifically in sub-Saharan Africa where they are most needed