NIH Scientists Identify Antibody That Neutralizes Nearly All HIV Strains
I read through the original paper (<a href="https:&#x2F;&#x2F;dx.doi.org&#x2F;10.1016&#x2F;j.immuni.2016.10.027" rel="nofollow">https:&#x2F;&#x2F;dx.doi.org&#x2F;10.1016&#x2F;j.immuni.2016.10.027</a>, paywalled).<p>In essence, an antibody called N6 was extracted from an HIV patient.  The patient is a long-term nonprogressor who has had HIV for 21 years, but an exceptionally low viral load of &lt;1000&#x2F;mL and normal CD4 T-cell count. This indicates that his immune system has kept the virus at bay for all these years with essentially no ill effect.<p>HIV viruses have a surface protein complex called Env, which binds to the CD4 surface protein to gain entry to T-cells (part of the immune system). HIV cannot transmit without this protein complex, and so certain parts of the complex are very well conserved across different HIV strains.<p>N6 binds to this part of Env, in some sense &quot;simulating&quot; CD4. However, because it&#x27;s just an antibody and not a cell, once Env is bound it cannot infect anything. This is what makes N6 a neutralizing antibody.<p>The thing that makes N6 special (more potent and more broadly applicable) is that it is able to avoid the parts of Env that HIV doesn&#x27;t need for replication. Imagine Env as a wrench. The head of the wrench is a specific hex shape to mate with CD4 and can&#x27;t change. Antibodies can grab on to the wrench handle to prevent infection. But the handle can change, and HIV regularly mutates this part to avoid being caught - adding side branches, changing the shape, and so forth. N6 is cleverly arranged so that it can strongly bind to the wrench without grabbing the handle too strongly - in other words, it tightly binds the head of the wrench like a person wrapping a thumb and index finger around it (this hand analogy appears in the paper). The result is that HIV has a much harder time getting out from under the antibody, since mutating itself to alter the head shape would also affect infectivity.<p>Now that larger HIV screening trials are done, and the technology has advanced to better detect such super-antibodies, more of these clever antibodies may be discovered. We may yet have a good shot at defeating this tricky virus!