Summary of the article Induction of Heterologous Tier 2 HIV-1-Neutralizing and Cross-Reactive V1/V2-Specific Antibodies in Rabbits by Prime-Boost Immunization. Samantha Townsley, Zeinab Mohamed, Wenjin Guo, Jennifer McKenna, Brad Cleveland, Celia LaBranche, David Beaumont, Xiaoying Shen, Nicole L Yates  4 , Abraham Pinter  5 , Georgia D Tomaras  4 , Guido Ferrari  4 , David C Montefiori, Shiu-Lok Hu. 2016 Sep 12;90(19):8644-60.  JVirol  doi: 10.1128/JVI.00853-16. Print 2016 Oct 1. PMID: 27440894 PMCID: PMC5021413 https://pubmed.ncbi.nlm.nih.gov/27440894/

HIV, the virus responsible for the AIDS disease, comes in two forms: a sensitive “tier 1” and a more resistant form, called “tier 2”. The latter form dominates the circulating strains.

There exists a trial of a vaccine against HIV, called RV144, which is the only immunization approach so far that has shown a modest level of protection against HIV. However, this vaccine works only against the sensitive (tier 1) forms; the “tier 2” forms remain free and active.

This study focused on developing antibodies against the “tier 2” form using a strategy of immunization where the component in the prime vaccine is slightly different from the component used in the booster vaccine.

With this immunization strategy applied to rabbits, the researchers generated antibodies capable of neutralizing HIV. These antibodies neutralized more than half of “tier 2” virus strains tested, but not all of them. The results indicate that it is possible to use this immunization strategy to produce antibodies against HIV, and that improvements to neutralize all “tier 2” types are achievable by changing the priming and boosting components.

These results shed light on the search for antibodies that can offer protection against HIV acquisition in humans and raise hope that one day a vaccine against HIV with very high efficacy will be produced.