Characterization of human IgM and IgG repertoires in individuals with chronic HIV-1 infection

Advancements in high-throughput sequencing(HTS)of antibody repertoires(Ig-Seq)have unprecedentedly improved our ability to characterize the antibody repertoires on a large scale.However,currently,only a few studies explored the influence of chronic HIV-1 infection on human antibody repertoires and many of them reached contradictory conclusions,possibly limited by inadequate sequencing depth and throughput.To better understand how HIV-1 infection would impact humoral immune system,in this study,we systematically analyzed the differences between the IgM(HIV-IgM)and IgG(HIV-IgG)heavy chain repertoires of HIV-1 infected patients,as well as between antibody repertoires of HIV-1 patients and healthy donors(HH).Notably,the public unique clones accounted for only a negligible proportion between the HIV-IgM and HIV-IgG repertoires libraries,and the diversity of unique clones in HIV-IgG remarkably reduced.In aspect of somatic mutation rates of CDR1 and CDR2,the HIV-IgG repertoire was higher than HIV-IgM.Besides,the average length of CDR3 region in HIV-IgM was significant longer than that in the HH repertoire,presumably caused by the great number of novel VDJ rearrangement patterns,especially a massive use of IGHJ6.Moreover,some of the B cell clonotypes had numerous clones,and somatic variants were detected within the clonotype lineage in HIV-IgG,indicating HIV-1 neutralizing activities.The in-depth characterization of HIV-IgG and HIV-IgM repertoires enriches our knowledge in the profound effect of HIV-1 infection on human antibody repertoires and may have practical value for the discovery of therapeutic antibodies.