Relationship between KIR genotypes and HLA-ligands with SARS-CoV-2 infection in the Saudi population

To ascertain whether killer cell immunoglobulin-like receptors (KIR) genes polymorphisms and HLA-I ligands are associated with COVID-19 in Saudi Arabia. Eighty-seven COVID-19 patients who tested positive for SARS-CoV-2 and onehundred and fourteen healthy controls were enrolled in this study for genotyping of the 16 KIR genes, HLA-C1 and -C2 allotypes and HLA-G 14-bp indels polymorphisms using the sequence specific primer polymerase chain reaction (SSP-PCR) method. KIR genotype frequency differences and combination KIR-HLA-C ligand were tested for significance. Framework genes KIR2DL4, KIR3DL2, KIR3DL3, and KIR3DP2 were present in all individuals. The frequencies of KIR2DL2 and KIR2D4 were higher in COVID-19 positive patients than in healthy individuals. The frequencies of the combination KIR2DL2-HLA-C2 was also significantly higher in patients affected by COVID-19 compared with healthy controls. It was found that the inhibitory KIR2DL2 gene in isolation or combined with its HLA-C2 ligand could be associated with susceptibility to COVID-19 in the Saudi population.