Science: inducing too many Th1 cells to produce will destroy the efficacy of HIV vaccine

November 22, 2019 / Biovalley BIOON / - -- if HIV vaccine causes the wrong immune response, the vaccination may be counterproductive Now, in a new study, researchers from the University of Emory and other research institutions in the United States have collected evidence from several non-human primate studies using SIV viruses closely related to HIV virus that building too many soft targets can weaken vaccination aimed at providing protection against virus infection HIV targets and replicates helper T cells (Th cells) that help the body produce an antiviral immune response They found it was crucial that vaccines against HIV did not create more safe havens for the virus The relevant research results were published in the Journal of Science Translational Medicine on November 20, 2019, with the title of "strong Th1 biased CD4 T cell responses are associated with determined SIV vaccine efficiency" The picture is from cc0 public domain The good news is that scientists can find early signs of a faulty immune system, said Dr Rama Rao Amara, co-author of the paper and a researcher at the Yerkes National Primate Research Center at Emory University Dr Eric hunter, co-author of the paper, said: "in order to induce a strong immune response, the vaccine should stimulate the production of an appropriate amount of Th cells If it stimulates the production of an excessive amount of Th cells, it will increase the sensitivity to the virus." Problems arise when vaccination produces too many specific types of type I helper T cells (Th1 cells) These cells migrate to mucosal tissues, such as the rectum, cervix and vagina In most infections, HIV / SIV first enters the body from mucosal tissue These Th1 cells are like the first responders to zombie attacks They initially fight HIV, but then they are taken over by the virus What people need is TFH cells, which stay in the lymph nodes and help the immune system produce antibodies against the virus, Amara said "We're not saying that Th1 cells are bad," he said However, if you have too many Th1 cells, they will make the vaccine unable to produce effective protection " Immunologists speculate that HIV vaccination may backfire The HVTN 502 / step clinical trial (2004-2007) seems to be stranded for this reason But since then, scientists in this field have learned a lot Looking forward to the future, following the successful RV144 clinical trial in Thailand ten years ago, scientists in the field of HIV vaccine are optimistic and conducting large-scale clinical trials Amara, "we need to get information about how adjuvants can lead immune responses into future clinical studies The effectiveness of a vaccine depends not only on the level of the immune response, but also on its quality " Adjuvants are vaccine components that enhance immune response, and some HIV vaccine studies are currently underway that combine adjuvants with synthetic copies of a part of HIV In this new paper, the researchers collected information from four studies in rhesus monkeys vaccinated with SIV or SHIV Depending on the study, vaccinated monkeys are attacked by SIV or SHIV in the vagina or rectum, the two most common routes of infection in humans For example, in the case of the intravaginal SHIV study, monkeys inoculated with high levels of antiviral Th1 cells did not delay SHIV infection compared to unvaccinated monkeys However, monkeys inoculated with lower levels of Th1 cells were somewhat immune to SHIV infection - two out of seven monkeys remained uninfected after eight SHIV attacks A similar effect was achieved in the intrarectal SIV study: only monkeys inoculated with lower levels of Th1 cells were well protected Th1 cells identified as destructive are more likely to persist in mucosal tissue than in blood, where they are sometimes difficult to detect Amara said scientists working on human HIV vaccine candidates should study whether they will produce too many Th1 cells It would be troublesome if people had to get samples of mucosal tissue from study participants "After a few months of vaccination, we found that Th1 cells are difficult to see in the blood compared to mucosal tissue," Amara said But a week after the initial vaccination, we can observe the gene expression characteristics of Th1 cells in the blood, which allows us to predict the future situation of mucosal tissue " He said the information could help immunologists design vaccines that are more reliable against HIV infection (BIOON Com) reference: 1 Venkateswarlu chamcha El Al Strong Th1 biased CD4 T cell responses are associated with divided SIV vaccine efficiency Science Translational Medicine, 2019, doi:10.1126/scitranslmed.aav1800 2.Creating viral targets can weaken HIV vaccination https://medicalxpress.com/news/2019-11-viral-weaken-hiv-vaccination.html