VACCINES work simply by producing antibodies, right? Well, probably not. And
this misconception coupled with basic ignorance of how they do work is stalling
the urgent quest for an AIDS vaccine, claim leading HIV researchers. They say no
one has bothered to find out how highly successful vaccines like polio, measles
and hepatitis B actually protect people from disease.
鈥淚鈥檓 amazed by the amount of basic science we don鈥檛 know,鈥� Philippe
Kourilsky, director of the Paris-based Pasteur Institute, told the meeting:
鈥淲e鈥檝e had many successful vaccines over the past decades but we鈥檝e missed a
chance to see how these vaccines work. Each time a vaccine works the scientific
community wanders off and leaves it to the public health workers to use
it鈥攁nd fails to invest in the research. If we had done that we would have
been in a much better position to tackle the AIDS vaccine problem.鈥�
The assumption that successful vaccines work by simply producing antibodies
is almost certainly wrong, Neal Nathanson, director of the US Office of AIDS
Research, warns. 鈥淗epatitis B vaccine is a good example. It鈥檚 amazingly
effective but no one knows how it works. And what鈥檚 really interesting is it
does work, even though HBV is a persistent infection鈥攍ike HIV.鈥�
Advertisement
The vaccine probably stimulates some protective effect relying on killer T
cells. But no one knows how it does it or what exactly the process is鈥攅ven
though the vaccine has been widely used for nearly ten years. It鈥檚 a similar
story for other highly successful vaccines including polio, measles and
smallpox, he says. Ruth Ruprecht, a vaccine researcher and professor of medicine
at Harvard Medical School, points out it鈥檚 hard to get funding to research
vaccines that already exist. 鈥淚 always run into prejudice,鈥� she told New
快猫短视频. 鈥淭hey say: `It鈥檚 old. What good is it?'鈥�
Even if researchers can plug these huge gaps in their basic understanding,
they may face another obstacle in their pursuit of an AIDS vaccine. Inducing
antibodies against HIV might, in the initial stages of infection, do more harm
than good, claims Ron Montelaro of the University of Pittsburgh.
His studies of a HIV-related virus that infects horses, known as the equine
infectious anaemia virus, appears to confirm that the antibodies which initially
respond to an infection can help spread the viruses around the body. Some
vaccines designed to protect horses from infection make them die more quickly
than unvaccinated horses, he found.
This process, whereby antibody production helps rather than hinders
infectious agents, has been dubbed 鈥渆nhancement鈥�. Montelaro suggests that these
early enhancing antibodies actually help pull virus particles into the cells
they are trying to infect. 鈥淚t鈥檚 an issue people haven鈥檛 wanted to think about.
But we might have to,鈥� he says. Jay Levy of the University of California at San
Francisco, agrees: 鈥淓fforts to avoid these harmful consequences of HIV
immunisation must be given a high priority.鈥�
