The phase I clinical trials of the first preventative HIV vaccine were completed with no adverse effects on patients. Other HIV vaccines are developed to prevent an HIV-positive individual from transmitting the virus to others, or remove the virus from the individual’s blood altogether: this vaccine aims to stimulate an immune response in uninfected individuals to prevent HIV from taking hold. Developed by Dr. Chil-Yong Kang in partnership at the Schulich School of Medicine & Dentistry at the University of Western Ontario and Sumagen Canada, the vaccine SAV001-H is a genetically modified killed whole virus vaccine. The phase I clinical trials took place from March 2012 to August 2013.
To create the vaccine, healthy cells are infected with genetically modified HIV-1. The infected cells produce many viruses, which are collected, purified, and deactivated using radiation and chemicals so as to not cause AIDS in recipients but still trigger immune responses.
The vaccine was tested on 24 healthy men and women 18-50 years of age who were HIV-positive. 18 received the killed whole HIV-1 vaccine, and six received the placebo. Volunteers recorded the adverse effects after vaccination for seven days in a diary. Afterwards, the volunteers visited test sites for blood work, urine tests, and physical examination by the investigators. No adverse effects, including local reactions, symptoms, and laboratory toxicity were found.
The presence of HIV antibodies and surface antigens were also measured and found to have increased drastically. This bodes well for future clinical trials, since the increase in antibodies and antigens show that even subtherapeutic doses of the vaccine trigger strong immune responses from the human body.
SAV001-H is also the first killed whole virus vaccine, like that for polio, influenza, rabies, and hepatitis A. HIV vaccines are difficult to develop because the virus has a high degree of genetic divergence, a long latency period, and does not retain its antigenicity – the creation of antigens – when it is killed.
While a pronouncement of “probably harmless” doesn’t seem especially exciting, it is important to remember that not all HIV vaccines have been able to clear Phase I of clinical trials. In 2004, a 3000 participant clinical trial for V520, a Thai vaccine using a weakened adenovirus carrying three HIV gene segments to provoke a cellular immune response to kill HIV-infected cells was discontinued after the vaccine appeared to increase HIV infection in some volunteers. Which is why Phase I of a clinical trials determines whether or not a drug is safe to check for efficacy.
Phase II tests the drugs on patients to determine if the drug can have any efficacy at all. Phase III determines the drug’s therapeutic effects. Phase IV occurs after vaccine distribution, and determines the drug’s long term effects.
If further clinical trials are successful, Sumagen hopes to distribute the vaccine within five years.
HIV has killed 28 million people worldwide. 34 million individuals currently live with the infection.
Around two dozen other HIV vaccines are being tested worldwide.
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