<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">On Apr 29, 2020, at 19:23, Michael Paoli <<a href="mailto:Michael.Paoli@cal.berkeley.edu" class="">Michael.Paoli@cal.berkeley.edu</a>> wrote:<br class=""><div><blockquote type="cite" class=""><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">(I recall hearing several examples, AIDs</span><br style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class=""> being just one such example ... body builds anti-bodies, but not</span><br style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class=""> immunity (with possibly some very rare exceptions? ... I heard several</span><br style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class=""> other common examples, but forget specifically what they were).</span></div></blockquote><div><br class=""></div>Immunity isn’t always a binary either.<br class=""><br class=""></div><div>1. Human herpesviruses, as DNA viruses, don’t have full immunity as those become part of the infected cells for life and part of the host cell's chromosomes. This is why the chickenpox vaccine (preventing the infection from taking hold) is different from the shingles vaccine (preventing reactivation of a latent infection years or decades later).</div><div><br class=""></div><div>2. HIV, special case of the DNA virus because it’s an RNA->DNA virus (and then analogous to above re chromosomes) and does some mojo. It’s particularly complex. Worth ten minutes: <a href="https://www.youtube.com/watch?v=5g1ijpBI6Dk" class="">https://www.youtube.com/watch?v=5g1ijpBI6Dk</a></div><div><br class=""></div><div>Why HIV is so particularly deadly: it targets the helper cells that help the immune system fight off infections and the virus sits there in the nucleus…until that cell is activated. Then when it’s activated, *boom*.</div><div><br class=""></div><div>3. Dengue, where you do create antibodies, and you might have immunity…or anti-immunity, depending on a) strain you had vs. strain you have next; b) how strong an immune memory you have on subsequent exposure; c) whether or not the immune response *itself* causes the virus to gain entry into the cells more readily.</div><div><br class=""></div><div><a href="https://www.nature.com/scitable/topicpage/host-response-to-the-dengue-virus-22402106/" class="">https://www.nature.com/scitable/topicpage/host-response-to-the-dengue-virus-22402106/</a></div><div><br class=""></div><div>I tried to find a good video about ADE in dengue and found…nothing that was useful to a layperson and under 15 minutes. :P</div><div><br class=""></div><div>That said, both of these are short and interesting and about viral replication of dengue and cool animations in their own right.</div><div><br class=""></div><div><a href="https://www.youtube.com/watch?v=3LhWuaTRCME" class="">https://www.youtube.com/watch?v=3LhWuaTRCME</a></div><div><br class=""></div><div><a href="https://www.youtube.com/watch?v=g8hLI3lXE38" class="">https://www.youtube.com/watch?v=g8hLI3lXE38</a></div><div><br class=""></div><div>The special point about #2 and #3 in particular is that the virus specifically targets cells that are part of the immune system (or in #3 *can* target them), which is not typically true of viruses. It’s why they’re sort of an extra special effect, if you will.</div><div><br class=""></div><div>Why this is a concern with all viruses/vaccines, though is that almost all cells have *some* antibody signaling proteins on them, and we need to understand how the virus gains entry both under regular circumstances and under special circumstances (e.g., ADE) to make sure that special case doesn’t happen as a result of a vaccine.</div><div><br class=""></div><div>Deirdre</div></body></html>