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Primate Studies Reveal Promising Vaccine Approach for HIV

| by darioringach

In the news today.

 

HILLSBORO, Ore. - Research conducted at Oregon Health & Science

University's Vaccine and Gene Therapy Institute (VGTI) has developed a

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vaccine candidate in non-human primates that may eventually lead to a

vaccine against Human Immunodeficiency Virus (HIV). Details of this

advance are published in the advance online edition of the journal Nature.

The paper will also be published in an upcoming print addition of the

journal.

 

The research team, led by Louis Picker, M.D., associate director of the

OHSU VGTI and director of the VGTI¹s vaccine program, produced a vaccine

candidate that programs the immune system of non-human primates to respond

more swiftly to the presence of a primate version of HIV than it normally

would. The team also included researchers from the National Cancer

Institute-Frederick and the International AIDS Vaccine Initiative.

 

The VGTI researchers tested their vaccine candidate in rhesus macaque

monkeys at the Oregon National Primate Research Center using a monkey form

of HIV called Simian Immunodeficiency Virus (SIV). Of the monkeys that

received the vaccine candidate, just more than half controlled replication

of the virus to the extent that even the most sensitive tests could not

detect signs of SIV.

 

To date, the vast majority of these animals have maintained control over

the virus for more than a year, gradually losing any signs that they had

ever been infected. In contrast, the macaques in the unvaccinated control

group developed the monkey form of AIDS.

 

The researchers say that their work suggests that the immune responses

elicited by this new vaccine candidate might completely clear SIV from

animals that were initially infected.  In comparison, antiretroviral

therapy is able to control the disease, but cannot clear the virus from

its hiding place within the immune systems own cells.

 

The VGTI team has been working for over ten years on its vaccine

candidate, which is unique in using Cytomegalovirus (CMV) as the transport

system used to introduce the vaccine into the body. CMV was chosen because

it is believed that most people are already infected with CMV, but for the

majority, the virus causes little or no symptoms. In addition, once a

person is infected with CMV, this virus remains in the body for life.

Picker and his team hypothesized that if such a persistent virus were used

as a vector it could create and maintain resistance against HIV by

programming a portion of the body¹s immune system called effector memory

T-cells to be constantly on the alert for the virus.

 

The next step in vaccine development is to test the vaccine candidate in

clinical trials in humans. For a human vaccine the CMV vector would be

weakened sufficiently so that it does not cause illness, but will still

protect against HIV, ² said Dr. Picker.

 

The National Institutes of Health and, the International AIDS Vaccine

Initiative provided funding for this research.