Powerful HIV vaccine being tested on humans

By Dr. Ananya Mandal, MDSep 29 2011

Spanish researchers have developed a prototype of a vaccine against the AIDS-causing HIV virus that is “much more powerful” than those made to date.

Mariano Esteban, of the National Biotechnology Center of Spain's CSIC research council; Felipe Garcia, with Barcelona's Clinic Hospital; and Juan Carlos Lopez Bernaldo de Quiros, with Madrid's Gregorio Marañon Hospital form the team that developed the vaccine.

After showing a high level of efficiency in mice and monkeys, testing was begun in humans a year ago and during the first phase the vaccine was administered to 30 healthy people selected from among 370 volunteers.

The study was “random and double blind,” that is to say that researchers did not decide which subjects would receive the vaccine and which would receive the placebo, and the people in the study also did not know which one they were receiving, said Lopez Bernaldo de Quiros.

Six people received the placebo and 24 the vaccine. The latter experienced “limited” and “slight” secondary effects (headaches, pain in the injection area or general discomfort), and so it can be confirmed that “the vaccine is safe for continuing with the clinical development of the product,” the researcher said.

Ninety-five percent of the patients who received the vaccine developed bodily defenses - although the normal rate for prior HIV vaccines has been 25 percent - and also, whereas other vaccines stimulate the production of cells or antibodies, this prototype “managed to stimulate both,” Felipe Garcia emphasized. In 85 percent of the patients, the defenses generated were maintained for at least a year, “which in this field is enough time,” he added.

Professor Mariano Esteban, head researcher on the project at the National Biotech Centre in Madrid, said of the jab, “It is like showing a picture of the HIV so that it is able to recognize it if it sees it again in the future.” The injection contains four HIV genes which stimulate T and B lymphocytes, which are types of white blood cells. Prof Esteban explained, “Our body is full of lymphocytes, each of them programmed to fight against a different pathogen. Training is needed when it involves a pathogen, like the HIV one, which cannot be naturally defeated.”

B cells produce antibodies which attack viruses before they infect cells, while T cells detect and destroy infected cells. The study showed that almost three-quarters of participants had developed HIV-specific antibodies 11 months after vaccination. Over a third developed one type of T cell that fights HIV, called CD4+, while over two-thirds developed another, called CD8+.

The researchers will now perform a new clinical trial, this time with volunteers infected with HIV, with the aim of learning if the vaccine, in addition to preventing AIDS can also be used to treat it.

The vaccine prototype, patented by the CSIC, is designed to combat HIV's subtype B, the one that is most prevalent in Europe, the United States, South and Central America and the Caribbean. The strain that is most widely spread in Africa and Asia is subtype C.

Other vaccines are in development. One, called the HIV-v vaccine, developed by British researchers, resulted in a 90 per cent reduction in viral count in HIV-infected people. Most trials so far have been small scale. There have also been many false starts with prospective HIV vaccines. Jason Warriner, clinical director for the Terrence Higgins Trust, described the Spanish project as “a step in the right direction”.