Two recent articles on chickens report some amazing and unexpected results. First, in a study published online on July 10 in Proceedings of the National Academy of Science (PNAS) scientists report on an antibacterial substance found in chickens (as well as in humans and swine) with previously unknown anti-cancer activity. Then, a second study, published online on July 13 in the journal Science, found that recombination between two viral strains, used in vaccines designed to prevent a type of herpes virus, has resulted in a new and deadly disease.
The PNAS report, led by researchers from Texas A&M University, USA together with researchers from Seoul National University, South Korea, have isolated the gene coding for NK-Lysin, a small protein that can be found in a variety of tissues in White Leghorn and Cornish chickens. NK-Lysin is a member of the so-called Anti-Microbial Peptides or AMP, which have an important role defending animals against pathogens. By isolating the DNA sequences that code for NK-Lysin they were able to identify 2 variations from the "normal" sequence, which were found to inhibit the growth of bacteria and cancer cells at extremely low concentrations. The two NK-Lysin variants differed both in their potencies and targets, one being more effective against microbes, whereas the other excelled against cancer cells. Future work with these variants will attempt to identify them in other species, such as cattle. It is known that inherited variations of AMPs can affect susceptibility to disease, and future research will seek to determine whether the variations found in the NK-Lysin gene are linked to the observed differences in resistance to either bacterial infection or cancer.
The Science article reports on research from the University of Melbourne, Australia, suggesting that two viral strains found in vaccines intended to prevent a deadly type of Chicken herpesvirus known as ILTV, have recombined to form a new and deadly strain of the virus. One vaccine, commonly found on the Australian market for prevention of ILTV, contained viral particles weakened by mutations in their DNA sequence. The virus retained the ability to multiply, but was no longer able to cause disease. In 2006, Australia purchased a new European vaccine and two years later, new and deadly strains of ITLV were isolated, which dominated previous strains. DNA sequencing of the new isolates revealed that the new viruses were a patchwork of European and Australian vaccines. The hypothesis is that recombination between the two viruses led to the "overwriting" of the mutations responsible for rendering the viruses innocuous.