# Association of a Novel IgG3 Allele With Malaria in Children From the Sepik Region of Papua New Guinea

## TL;DR

A new IgG3 antibody variant is found to be common in children in Papua New Guinea and is linked to fewer malaria infections, especially from Plasmodium vivax.

## Contribution

The discovery of a novel IgG3 allele (IGHG3*30) associated with reduced malaria infections in children from East Sepik, Papua New Guinea.

## Key findings

- 78% of children in the study had the IGHG3*30 allele, which is associated with fewer Plasmodium infections.
- Children with IGHG3*30 had on average one fewer Plasmodium vivax infection over 18 months.
- IGHG3*30 carriers had lower IgG levels to P. vivax vaccine candidate proteins.

## Abstract

Susceptibility to malaria can be influenced by host genetic factors, including immune response genes. Antibodies against Plasmodium antigens are known to play an important role in protection from clinical disease. Polymorphisms in these antibodies may result in different functional properties that could provide protection from malaria.

Immunoglobulin G1 (IgG1) and immunoglobulin G3 (IgG3) alleles and IgG3 hinge region were investigated by polymerase chain reaction and Sanger sequencing in a longitudinal cohort of children aged 1–3 years (N = 203) from the East Sepik region of Papua New Guinea. Linear regression was used to investigate associations between immunoglobulin alleles and Plasmodium infections.

Seventy-eight percent of the children were either heterozygous (n = 82 [40%]) or homozygous (n = 77 [38%]) for IGHG3*30 (G3m29), a novel IgG3 allele. G3m29 has a long hinge region of 4 exons. Significantly fewer Plasmodium spp infections were observed in children with the IGHG3*30 allele compared to children without the allele (β = −1.736 [95% confidence interval {CI}, −3.39, −.079]; P = .038). This effect was most noticeable for Plasmodium vivax asymptomatic infections as IGHG3*30 carriers had on average 1 fewer infection in the 18-month follow-up period compared with non-IGHG3*30 allele carriers (β = −1.06 [95% CI, −2.01, −.12]; P = .028). Additionally, IGHG3*30 allele carriers had significantly lower levels of IgG to P vivax vaccine candidate proteins compared to non-IGHG3*30 allele carriers.

The IGHG3*30 allele is highly prevalent in the East Sepik region and is associated with fewer Plasmodium spp infections.

A novel IgG3 allele (IGHG3*30) is highly prevalent in the East Sepik region of Papua New Guinea. IGHG3*30 is protective against Plasmodium spp infections, particularly P vivax asymptomatic infections, with a possible mechanism being antibody-dependent phagocytosis.