Illustration of the reconstruction process of HERV Env proteins.
The first step was to extract env genes for both endogenous and exogenous retroviruses from Literature, Dfam, NCBI, Uniprot, and PDB (complete env sequence as well as defective env genes). Second, we performed group specific alignments for all the ERV sequences with Mafft and further divided the sequences into subtypes based on the alignments, as in case of HERV3 and HML3. Then, we translated the sequences into three forward frames in the alignment and extracted only the translated portions that did not have any stop codons. Lastly, the extracted aa portions were aligned to the reference sequence of each group and hence, a reconstructed env sequence was generated for HERV groups as mentioned in Table 1.