A Canadian-made HIV vaccine has cleared a major hurdle. Scientists announced on Tuesday that initial results from human clinical trials show no adverse effects and significantly boosted immunity.

Developed by researchers at Western University in London, Ont., it’s the first and only preventative HIV vaccine based on a genetically modified killed whole-virus. It has shown promising results after Phase 1 trials.

“These are very exciting results,” said Dr. Chil-Yong Kang, professor of virology at the university’s Schulich School of Medicine and Dentistry. “It is, really, a major milestone.”

Last year, the United States Food and Drug Administration approved human clinical trials on the vaccine, called SAV001-H.

It’s the only HIV vaccine being developed in Canada. Currently, there are more than 30 HIV vaccines being tested in human clinical trials worldwide, according to International AIDS Vaccine Initiative (IAVI), a global not-for-profit organization.

Kang’s vaccine is unique in that it uses a killed whole HIV-1 virus to activate immune response — a strategy used to develop successful vaccines for influenza, polio, rabies and hepatitis A.

The human immunodeficiency virus used in the vaccine is genetically altered so that it’s nonpathogenic, or unable to cause disease, and can be produced in large quantities. Chemicals and radiation are also used to further inactivate the virus.

Phase 1, designed to see if the vaccine was safe for humans, began in March, with 24 HIV-positive volunteers at two Los Angeles clinics. Participants, men and women aged 18 to 50, were divided into two groups, with 18 people receiving the vaccine and six given a placebo.

“There were no adverse effects,” said Kang, who developed the vaccine for a decade.

Participants have undergone monthly checkups and to date, there have been no local reactions, signs or symptoms since the injection. The biggest complaint was a sore arm — but that only lasted a day and is to be expected with any shot, said Kang.

“And after the vaccination, the level of (HIV-1) antibodies increased significantly. That means our vaccine is working to stimulate the immune responses.”

Researchers were expecting a two or threefold increase in the level of HIV-1 antibodies, but were pleasantly surprised when one individual showed a 32-fold increase, and another a 10-fold increase.

“Phase 1 was the biggest hurdle,” said Kang, adding this success paves the way for upcoming clinical trials.

Dr. Jonathan Angel, an infectious disease specialist and president of the Canadian Association for HIV Research, said Tuesday’s announcement is “encouraging but very, very preliminary.”

According to IAVI, developing an effective vaccine is challenging because the virus has developed ways to evade the body’s defences, targets the very cells that co-ordinate immune response to viral infections and has an extraordinary ability to mutate.

HIV is the cause of acquired immunodeficiency syndrome (AIDS), which has killed about 28 million people worldwide. Advances in treatment have largely transformed HIV from a fatal to chronic disease, with about 34 million people currently living with the infection.

Phase 2, to begin next year, will entail testing the vaccine on 600 HIV-negative volunteers at high risk for infection so researchers can measure immune response. It will take about a year.

Phase 3 involves testing 6,000 HIV-negative men and women at high risk for infection. Researchers will determine whether the vaccine successfully prevents infection.

The second and third phases will be carried out in Canada, the United States and in Europe. The CIHR Canadian HIV Trials Network, which facilitates HIV clinical trials, has shown interest in testing the vaccine in the upcoming trials, said Kang.

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“In order to make enough volunteers available for the vaccination I think we need to have this trial available in many different countries,” said Kang.

If the vaccine proves effective, it could be on the market in about five years, he said. It would be given to high-risk groups such as sex workers, men who have sex with men, injection drug users and hemophiliacs.

Sumagen Canada, a company that was created in 2008 to support the vaccine’s development, has provided funding. It’s a subsidiary of Sumagen Co. Ltd., a Korean-based pharmaceutical venture company.