Recombinants

Recombinant refers to a DNA molecule or an organism that contains genetic material from two or more sources that have been joined, either artificially or through natural processes. In genetics, recombinant DNA technology enables combining sequences from different organisms. In virology, recombinant viruses arise from genetic exchange between co-infecting strains.

Mechanisms of recombination include homologous recombination, where long identical stretches of DNA exchange segments; site-specific recombination, mediated by specialized enzymes at defined sequences; and non-homologous end joining, which joins ends without extensive sequence similarity. In nature, recombination contributes to genetic diversity during meiosis and to horizontal gene transfer in bacteria and archaea.

In biotechnology, recombinants are generated by inserting DNA fragments into vectors such as plasmids or viral genomes and introducing them into host cells to propagate or express the inserted genes. Recombinant proteins, including insulin and various growth factors, are produced in engineered organisms. Recombinant methods underpin gene cloning, functional genomics, and the development of many diagnostic tools and therapeutics, including some vaccines and gene therapies.

In viruses, recombination can give rise to new strains with altered properties, affecting pathogenicity, host range, or drug resistance. Examples include circulating recombinant forms of HIV-1 and other RNA viruses, though the significance and frequency of recombination vary by organism. Recombination also informs evolutionary studies and poses considerations for biosafety and vaccine design.

Applications span medicine, agriculture, and basic research. Recombinant DNA techniques enable dissection of gene function, production of biologics, and rapid development of vaccines. Regulatory and ethical frameworks govern their use to manage risks associated with foreign genetic material and potential environmental impacts.