If you are expecting to live past 40, or are there already, chances are you have modern vaccines, in part, to thank. Since Edward Jenner introduced the idea of vaccination in the 18th century vaccines have become the most effective means of fighting infectious disease worldwide. Smallpox is now eradicated worldwide, wild polio is nearly gone and deaths from diseases such as measles and tetanus have plummeted.
New vaccines are hard to find and expensive to test however. Human testing is unethical in some diseases, such as HIV. New and emerging diseases are often dangerous to work with and have no animal models.
What’s needed, say Joseph Legutki and Stephen Johnston, is a way to evaluate vaccines in natural hosts without vaccinating, then attempting to infect a healthy population. These Arizona State University researchers detail a chip-based method for quickly and automatically screening for vaccine efficacy in PNAS Early Edition.
For the past several years Legutki and Johnston have used microarrays to detect the presence of antibodies circulating in an organism. Their chips, CIM10Ks, were developed at the Center for Innovations in Medicine at the Biodesign Institute at ASU. CIM10Ks hold arrays of 10 thousand peptides, each 20 amino acid lengths long. Based on their binding preference, antibodies attach to one or more of the segments. There is enough variation in the peptide sequences, they say, to get a complete readout of all present antibodies. This produces “a true signature of an individual’s reactivity profile, including any disease or vaccine they have had,” they write.
In their most recent work, Legutki and Johnston use “immunosignatures” to look for correlates that predict how well a vaccine works. By comparing the immune response to two kinds of vaccines, one affording complete protection, the other partial, the immunosignatures could distinguish which was most effective. Individuals vary in how they respond to the same diseases — viruses that kill one person (or mouse) will only make another sick. Immunosignatures, the researchers found, could be used to predict that variability. They were also interested in using the microarrays to find which protective antigens were fighting the disease (a mouse virus in this case). Potentially that could provide a basis for building the best vaccines. Using microarrays in these ways will, they hope, significantly shrink the expense and time needed to test new vaccines.
Beyond vaccine development, they write, the ability to predict if an individual will survive an infection could help direct who gets vaccines during times of shortage. Also, the most protective vaccine could be selected, they write, by comparing the immunosignatures of survivors to the immunosignatures of stockpiled vaccines in the event of a pandemic.