Health In Focus
  • HIV is currently managed with a combination of anti-HIV medications
  • The medications are sometimes beyond the reach of those who need them
  • A vaccine could be a boon to several individuals exposed to this deadly viral infection

A new strategy of delivering the HIV vaccine could probably pave the way to the availability of a vaccine for the chronic immune disease. A study indicating the same was published in the Immunity.

Human immunodeficiency virus, the virus that causes AIDS, reduces the immunity to such an extent that the person becomes prone to various infections and cancers that are not as common in people with normal immunity. Two approaches were adopted to deal with the increasing number of HIV incidences. One approach was aimed at developing drugs that maintain the immunity levels in the individual after the patient was exposed to the virus. The second approach was to prevent the infection, through education, and the development of a vaccine. While the development of drugs has taken giant leaps and drug combinations have been able to prolong lives, the development of a vaccine has faced several hurdles, and has yet to see the light of day.
A Step Forward in HIV Vaccine Efficacy

One barrier to vaccine development was the inability of the tested vaccines to reliably generate neutralizing antibodies. Antibodies are proteins that develop after exposure to the viral protein, and protect against future infection. Neutralizing antibodies are antibodies that attach themselves to the invading virus and prevent them from establishing themselves in the body. The trimeric envelope immunogens used in the recent vaccines closely mimic the antigens on the HIV virus, and appear to produce good antibody response. However, the response produced is not reliable.

A research team from the Scripps Research Institute (TSRI) and the La Jolla Institute for Allergy and Immunology (LJI) claim that they might have found an answer to this problem of generating and maintaining neutralizing antibodies by altering the way the vaccine is administered.

The team conducted their studies in rhesus macaques. The macaques are considered a good model since their immune systems appear to be very similar to those of humans. The team tested various vaccines as well as different strategies of administration. They found that, by changing the strategies used to administer the vaccine, a good immune response could be achieved. These methods included:
  • Administering the vaccine subcutaneously, that is, just below the skin instead of the usual intramuscular route.
  • Increasing the time intervals between the first and second vaccination dosage from the usual 4 to 6 weeks to 8 weeks.
  • Administering the vaccine slowly and continuously over 2 weeks through osmotic pumps. However, this may not be a practical option.
The above strategies resulted in the development of the neutralizing antibodies after 10 weeks. This was in contrast to the development of antibodies after 3 to 6 months, as noted in HIV-infected individuals.

The research team also feel that the use of a stronger adjuvant and bilateral immunizations in the study could have also contributed to the better effectiveness of the vaccine.

Thus, by altering the way in which the vaccine is administered, one might arrive at a much better response. The use of such strategies might help to create a vaccine that could save millions, exposed to the deadly HIV virus in the near future.

Reference :
  1. Pauthner M et al. "Elicitation of robust Tier 2 neutralizing antibody responses in non-human primates by HIV envelope trimer immunization using optimized approaches." Immunity (2017). Doi: 10.1016/j.immuni.2017.05.007.
Source: Medindia

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