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A new study published in The Lancet shows that an experimental HIV-1 vaccine regimen is well tolerated and produces comparable and robust immune responses against HIV in healthy adults and adults. rhesus monkeys. In addition, the candidate vaccine has protected against infection with an HIV-like virus in monkeys.
Based on the results of this phase 1 / 2a clinical trial involving nearly 400 healthy adults, a phase 2b trial was initiated in southern Africa. determine the safety and efficacy of the HIV-1 vaccine candidate in 2,600 women at risk of contracting HIV. This is one of five experimental designs of HIV-1 vaccines that have progressed toward efficacy trials in humans over the 35 years of the global HIV / AIDS epidemic. AIDS.
world. The experimental designs tested in this study are based on "mosaic" vaccines that take pieces of different HIV viruses and combine them to trigger immune responses against a wide variety of HIV strains
. "These results represent a milestone. that the ad26 prime mosaic, Ad26 plus gp140 boost candidate HIV vaccine induces robust immune responses in humans and monkeys with comparable magnitude, kinetics, phenotype and durability and 67% protection against viruses in monkeys ", explains Professor Dan Barouch of the Center for Research in Virology and Vaccines at the Beth Israel Deaconess Medical Center and Professor of Medicine at Harvard Medical School in Boston, USA, who led the study
He adds: "These results should be interpreted with caution, an HIV vaccine is unprecedented, and the ability to induce responses Immunity specific to HIV does not necessarily indicate that a vaccine will protect humans from HIV infection. We look forward to the results of the Phase 2b efficacy trial called HVTN705, or "Imbokodo", which will determine whether this vaccine will protect humans against HIV infection or not.
Nearly 37 million people are living with HIV / AIDS, with an estimated 1.8 million new cases each year, a safe and effective preventative vaccine is urgently needed to stem the HIV pandemic.
In the 35 years of the HIV epidemic, only four HIV vaccine concepts were tested. one provided proof of protection in an efficacy test – a premium canarypox vector, gp120 boost vaccine tested in the RV144 trial in Thailand reduces the human infection rate of 31 %, but the effect was considered too low to advance the common vaccine
A major obstacle to the development of HIV vaccine was the lack of direct comparability between clinical trials and preclinical studies To address these issues Methodologists, Barouch and colleagues evaluated ding mosaic adenovirus candidate HIV-1 vaccines based on serotype 26 (Ad26) in parallel clinical and preclinical studies to identify the optimal vaccine regimen against HIV in order to progress in clinical trials Efficiency
adults (aged 18 to 50 years) from 12 clinics in East Africa, South Africa, Thailand and the United States between February 2015 and October 2015. The will Areas were randomly badigned to receive one of seven vaccine combinations or a placebo. Immunizations over a 48-Week Period
To stimulate or "prime" an initial immune response, each volunteer received an intramuscular injection of Ad26.Mos.HIV at the beginning of the study and again 12 weeks later. The vaccine containing the HIV Env / Gag / Pol "mosaic" antigens was created from numerous HIV strains, delivered with the aid of a non-replicating common cold virus (Ad26).
To boost the body's immune response level two additional vaccinations at weeks 24 and 48 using various combinations of Ad26.Mos.HIV or a different vaccine component called Modified Vaccinia Ankara (MVA) with or without two different doses of envelope protein gp140 clade C HIV containing aluminum adjuvant.
The results showed that all vaccine regimens tested were able to generate anti-HIV immune responses in healthy individuals and were well tolerated, with a similar number of local and systemic reactions reported in all groups, including severity. was mild to moderate. Five participants reported at least one vaccine-related Grade 3 adverse event, such as abdominal pain and diarrhea, postural dizziness, and back pain. In a parallel study, the researchers evaluated the immunogenicity and protective efficacy of the same Ad26-based mosaic vaccine regimens in 72 rhesus monkeys using a series of repeated challenges with the HIV virus. Simian-human immunodeficiency. (SHIV) – a virus similar to HIV that infects monkeys.
The Ad26 / Ad26 plus gp140 vaccine candidate induces the greatest immune responses in humans and also offers the best protection in monkeys – providing complete protection against SHIV infection in humans. two-thirds of animals vaccinated after six challenges
The authors note several limitations, including the fact that the relevance of vaccine protection in rhesus monkeys to clinical efficacy in humans remains unclear. They also note that there is no definitive immunological measurement known to predict protection against HIV-1 in humans.
Writing in a related commentary, Dr. George Pavlakis and Dr. Barbara Felber of the National Cancer Institute in Frederik, Maryland, USA say: "Efficacy studies are needed to determine the protective capacity in humans and also for the discovery of correlates of protection and to determine if the same or different immune correlates apply to different vaccine regimens It remains to be determined if an improved efficacy on RV144 will be The new concepts and vectors of vaccines are under development and can evolve towards efficacy trials, which is an important process since the development of an AIDS vaccine remains urgent.P prophylaxis, the number of people living with HIV continues to increase in n a moderately effective HIV vaccine, and existing HIV prevention and treatment strategies should greatly contribute to l & # 39; evolution of the HIV / AIDS. It is therefore essential that a commitment to pursue multiple vaccine development strategies continues at all stages. "
SOURCE: The function of the Lancet
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