Late-breaking Poster Asia-Pacific Vaccine and Immunotherapy Congress 2024

Role of IgG antibodies in protection from placental malaria birth outcomes (#150)

AKACHUKWU ONWUKA 1 , Elizabeth Aitken 1 2 , Wina Hasang 1 , Mwayiwawo Madanitsa 3 4 , Victor Mwapasa 5 , Kamija Phiri 6 , Feiko O ter Kuile 4 , Stephen Rogerson 1 7
  1. Department of Infectious Diseases, The Peter Doherty Institute of Infection and Immunity , University of Melbourne, Melbourne, Victoria, Australia
  2. Department of Microbiology and Immunology, UNIVERSITY OF MELBOURNE, melbourne, Victoria, Australia
  3. Department of Clinical Sciences, Academy of Medical Sciences, Malawi University of Science and Technology,, Thyolo, Malawi
  4. Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
  5. Department of Epidemiology and Biostatistics, School of Global and Public Health, Kamuzu, Blantyre, Malawi
  6. Training and Research Unit of Excellence, Blantyre, Malawi
  7. Department of Medicine (RMH), The Peter Doherty Institute of Infection and Immunity, University of Melbourne, Melbourne, Melbourne, Victoria, Australia

Placental malaria (PM) is a public health issue linked to poor pregnancy outcomes. Antibodies against VAR2CSA, a variant surface protein found on infected erythrocytes, protect against Plasmodium falciparum infections in pregnant women. This study aims to associate VAR2CSA antibody levels with poor pregnancy outcomes: low birthweight (LBW), preterm delivery, small for gestational age (SGA), and maternal anaemia. Pregnant Malawian women (n=466) were recruited at mid-pregnancy (16-28 gestation weeks). The pregnant women were subdivided into women infected at enrolment and infected later in pregnancy. Total IgG levels to recombinant VAR2CSA (DBL1X-ID2a) domains were measured at enrolment and delivery via indirect ELISA. The IgG antibody levels were log-transformed, and the arbitrary results (AU) were represented as mean + SEM. There were higher log IgG antibody levels in multigravid women who were infected at enrolment (3.50 ± 0.10 AU) than primigravid women (3.38 ±0.10 AU). Higher antibody levels were observed at enrolment (3.45 ±1.09 AU) compared to delivery (2.89 ± 0.97 AU). However, log IgG antibody levels measured at enrolment were not associated with reduced LBW (aOR=1.16, 95%CI 0.81-1.67, p= 0.4), preterm delivery (aOR=1.24, 95%CI 0.81-1.88, p=0.32), SGA (aOR=0.96, 95%CI 0.74-1.25, p=0.75) and maternal anaemia (aOR=1.08, 95%CI 0.84-1.40, p=0.55). This shows no significant associations between the antibody levels at enrolment with protection from poor pregnancy outcomes. The antibody responses to VAR2CSA are likely markers of placental malaria rather than protection from the infection.