Immunologists have identified two bigÂ groups of TÂ cells:Â “helper” CD4+ cells and “killer” CD8+ cells.* The helper cells can produce immune regulatory molecules and promote antibody responses, while the killer cells recognize and destroy virally-infected cells.
A vaccine against a virus that stimulatesÂ only helper CD4+ cells leads to uncontrolled lethalÂ inflammation in mice once the animals are challenged with the virus, a recent paper in Science shows. Emory Vaccine Center director Rafi Ahmed is a co-author.
Senior author Dan Barouch, from Harvard/Beth Israel Deaconess Medical Center, tellsÂ The Scientist that CD4+ cells are like generals directing the battleÂ of the immune system and “if you just have strategic generals and no soldiers,Â it turns out to be worse than having no army at all.” Rebalancing the system with antiviral CD8+ T cells or antibodies helps limit the problems.
The findings mesh with work by Yerkes investigators [Guido Silvestri and colleagues]Â suggestingÂ that HIV vaccines that boost CD4+ cells in gateway mucosal tissues lead to higher rates of infection. In both cases, the lesson is: having more helper CD4+ T cells aroundÂ actually does not help. Read more
Emory Vaccine Center director Rafi Ahmed, is a co-author on a recent Science paper advocating a â€œHuman Vaccines Projectâ€. Wayne Koff, chief scientific officer of IAVI (International Aids Vaccine Initiative) is lead author and several other vaccine experts are co-authors.
The idea behind a â€œHuman Vaccine Projectâ€ is to combine efforts at developing vaccines for major (but very different) diseases such as influenza, dengue, HIV, hepatitis C, tuberculosis and malaria, with the rationale that what scientists working on those diseases have in common is the Ray Ban outlet challenge of working with the human immune system.
Technology has advanced to the point where whole genome-type approaches can be brought to bear on vaccine problems. The authors cite work by Bali Pulendranâ€™s laboratory on â€œsystems vaccinologyâ€ and their analysis of the yellow fever vaccine as an example.
One major puzzle confronting vaccine designers is to coax the immune system into producing broadly neutralizing antibodies against a rapidly mutating virus, whether it is Gafas Ray Ban outlet influenza or HIV. Our own Cynthia Derdeyn has been analyzing this problem through painstaking work following how the immune system pursues a twisting and turning HIV.
An interesting related tidbit:
There are hints that the reverse engineering of vaccines has taken a leap forward in the case of RSV (respiratory syncytial virus): Scientists at Scripps Research Institute have designed vaccine components by computer and have used them to provoke neutralizing antibodies in monkeys.
Also check out Mike Kingâ€™s feature in Emory Health on HIV vaccine research.