Sequencing of Sylvilagus VDJ genes reveals a new VHa allelic lineage and shows that ancient VH lineages were retained differently in leporids

Antigen recognition by immunoglobulins depends upon initial rearrangements of heavy chain V, D, and J genes. In leporids, a unique system exists for the VH genes usage that exhibit highly divergent lineages: the VHa allotypes, the Lepus sL lineage and the VHn genes. For the European rabbit (Oryctolagus cuniculus), four VHa lineages have been described, the a1, a2, a3 and a4. For hares (Lepus sp.), one VHa lineage was described, the a2L, as well as a more ancient sL lineage. Both genera use the VHn genes in a low frequency of their VDJ rearrangements. To address the hypothesis that the VH specificities could be associated with different environments, we sequenced VDJ genes from a third leporid genus, Sylvilagus. We found a fifth and equally divergent VHa lineage, the a5, and an ancient lineage, the sS, related to the hares’ sL, but failed to obtain VHn genes. These results show that the studied leporids employ different VH lineages in the generation of the antibody repertoire, suggesting that the leporid VH genes are subject to strong selective pressure likely imposed by specific pathogens.This work was partially funded by FEDER (Fundo Europeu de Desenvolvimento Regional) funds through the Programa Operacional Factores de Competitividade (COMPETE program; FCOMP-01-0124-FEDER-028286) and Portuguese national funds through FCT (Fundação para a Ciência e a Tecnologia; research project PTDC/BIO-ANM/3963/2012)—Quadro de Referência Estratégico Nacional (QREN) funds from the European Social Fund and Portuguese Ministério da Educação e Ciência. FCT also supported the doctoral grant of AP (ref.: SFRH/BD/71252/2010) and the FCT Investigator grant of JA (ref.: IF/01396/2013) and the Post-Doctoral grant of JMF (ref.: SFRH/BPD/43264/2008). “Genomics Applied to Genetic Resources” co-financed by North Portugal Regional Operational Programme 2007/2013 (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF), also supported this work.Peer Reviewe