Fighting HIV Without Traditional Vaccines

Why can't scientists just develop a universal vaccine against HIV and the swine flu? Is it because the biopharm industry wants to make money each year off of a new vaccine?

The answer to the second question is a definite "no", but the answer to the first question is far more complicated....

The problem is that HIV, and in fact many viruses, do not play fair. Viruses, although not technically "alive", evolve over time. One way that viruses evolve is by changing the protein structure of their outer protein coat. This protein coat is responsible for the majority of the properties of a virus - for example what species and types of cell in infects. In viruses, the evolutionary rate of change is higher than that of living organisms, for several reasons, including the fact that viruses lack DNA repair mechanisms. This means that they accumulate mutations faster, and often these mutations change the outer structure of the virus. Since vaccines are prepared using purified outer proteins of a virus, you can see how as viruses evolve they make previous vaccines ineffective. Such is often the case in the flu vaccine, where the yearly vaccines are prepared from the previous year's flu viruses. Vaccines for HIV has so far met limited success, and epidemiologists balk at the idea of putting a vaccine on the market which would make people think that they are safe. Furthermore, HIV belongs to a class of viruses called the retroviruses, an especially nasty sub-set of viruses that accumulate mutations faster than most.

Vaccines, when introduced into the body, cause the immune system to target specific cells and proteins for destruction. This is called the specific immune response, and one of the ways that it works is to produce antibodies against the invading virus. Unfortunately, we all do not generate the same antibodies, meaning that a vaccine in one person might not have the same result as in another. Coupled with the high mutation rates of viruses, this causes real problems in developing a population-wide vaccine for highly mutable viruses.

But what if we could bypass the whole antibody-generation step and instead introduce virus-specific antibodies into the body. These antibodies could be designed to target a specific type of virus, and would actively recruit the cells of our immune system to destroy the virus before it caused significant damage. This type of procedure has just been reported for HIV-type infections in primates, and the initial results suggest that it might hold promise. And not only for HIV, but also for viruses such as H1H1 (swine flu) and H5N1 (avian flu). Both of these are now in the human population, and the development of an effective vaccine against them both is not soon forthcoming, so adding a new technique to our anti-viral arsenal is well advised.


For more information - see Jon Cohen's article in ScienceNow
"Designer Antibodies Derail Monkey AIDS Virus"

The Battle Against Viruses Heats Up

Viruses are nasty opponents, as anyone who has followed the battles against influenza, SARs and HIV/AIDS can attest. They are diverse and in many cases evolve at rates that confound efforts to contain them. Anyone who has gotten a flu shot, and then came down with the flu a few months later because the “strain” of virus that the vaccine was not the same as the “strain” that they were infected with, knows just how fast viruses can evolve. In many cases, medical professional never really know which virus has caused the symptoms in their patients, and this complicates treatment and often leads to the misuse of antibiotics, which, of course, are never effective against viruses.

At the ScienceWriters 2008 New Horizons in Science meeting at Stanford University (sponsored by CASW) this week, Dr. Joseph DeRisi of UCSF presented an interesting talk on his research to develop a new form of “chip” as a diagnostic tool for identifying the viral contributions to diseases. Gene chips are often used by molecular biologists to determine the relationship between a gene and an observed condition. Dr DeRisi's work takes this approach one step further.

What is interesting here is Dr. DeRisi’s application of evolutionary genomics to his work. Like microbiologists, virologists recognize that they have only identified a small fraction of the diversity of viruses that are out there in the natural world. Despite advances in sequencing technology, the ability to sequence every virus in a given environment, such as a fecal or nasal sample, is still not cost effective. However, what Dr DeRisi has done is to develop a “viral chip” that contains not the entire sequences of every virus, but rather the sequences of key genes that are evolutionarily important to certain families of viruses. When one of these viral chips is exposed to a sample, a computer program determines the level of similarity between the DNA (or RNA) in a virus and the sequence on the chip. For previously unknown viruses, this can allow a quick classification of the virus to a certain group, and has been proven to be very successful by Dr. DeRisi’s team in diagnosing diseases for which no known cause could be determined by diagnostic tools.

Furthermore, Dr DeRisi has proposed making these chips available at cost to the medical community through a non-profit organization. The availability of a new technology at an inexpensive cost would represent an important new development in the war against viruses, and would rapidly generate an increase in data for public health officials.

Additional Links

DeRisi Lab at UCSF

Good News, and Old News, about HIV

There were several important announcements in the HIV/AIDS battle this week. First was the awarding of the Nobel Prize in physiology or medicine to two French virologists,Françoise Barré-Sinoussi and Luc Montagnier, for discovering that the HIV virus causes AIDS. The side story here is the controversy that the American scientist Robert Gallo is credited by some as being the "first" to discover the virus. "First" is very important to scientists, therefore, there have been some pretty heated exchanges between Montagnier and Gallo in the past. If you are interested in some good drama, there are some decent books out there on the subject, including opposing views written by both Gallo and Montagnier.




The Nobel committee has attempted to end the dispute by announcing that Montagnier was the discoverer, a fact that is widely accepted by the scientific community, but given that there is no love lost between the Americans and the French, it is doubtful that this will die down soon.

The second announcement was that the HIV virus is probably much older than we originally thought. A discovery at the University of Arizona by Dr. Michael Worobey backs the date that the virus jumped from chimps to humans sometime around 1900 - at least 30 years earlier than originally thought.

This should not be treated as some sort of background story. In fact, it is probably the most important, and under-reported, story of the week. If you take a look at the map from the CDC below, you can see that the AIDS pandemic is showing no signs of abating.



By understanding when the virus actually made the jump from chimps to humans, we can get a better grasp on its rate of evolution. One of the biggest obstacles to the development of effective HIV vaccines has been the rapid mutation rate of the virus. As a virus mutates, it evolves, or changes, its associated proteins. Vaccines frequently target the unique proteins on the surface of a virus. Without an understanding of how this virus is continuing to evolve, the development of a vaccine could actually create more harm than good, since vaccinated people may feel that they are "safe" and can return to unsafe sexual practices and other risky behaviors. Worobey's work should provide some important insight into how HIV evolves. We should be seeing some interesting developments in the near future stemming from this discovery.