Researchers at the University of Colorado Boulder have been studying a protein called Schlafen 11 (SLFN11), which was found to inhibit HIV-1 replication in the early stages of infection back in 2012. Although this protein caused a lot initial excitement, it has not been effective at eliminating HIV when present in human systems.
To find out why, researchers analyzed the human form of the protein and compared it to several primate versions. They found out that chimpanzees, orangutans, gibbons and marmosets have very potent SLFN11 action as compared to that of humans and gorillas. In the active versions of SLFN11, the antiviral had stronger blocking actions against production of HIV-1 proteins, and interestingly also reduced protein production of nonviral proteins like green fluorescent protein and host proteins like Vinculin and GAPDH. Researchers believe that SLFN11 may generally reduce protein production from non codon optimized transcripts, which would put the host in a constant antiviral state.
\Schlafen11 protein is likely interferon induced and human does not show the same powerful properties as some primate proteins. Researchers at Boulder believe this gives insight into the rapidly evolving nature of the immune system. Over time since our evolutionary divergence, primate SLFN11 has taken on a very important role in primate immunity, and has not had the same optimization in humans or gorillas. In fact, the researchers believe that the strong selection for the SLFN11 protein in most primates is more than would be selected for by HIV alone. There are likely other pathogenic agents that it acts against that are as of yet unknown.
Although human SLFN11 is not as potent as primate protein, the research bodes well for possible antiviral treatments and discovery in the future.
Humans and Viruses 16-17