Reading widely in journals allows random inputs that percolate in the interstices of the mind and eventually help solve problems. Reading journals may not seem as exciting as random inputs from wandering the streets of Rome or trekking through the Grand Tetons, but journals are handy, never-ending sources of stimulation. I realize that there is an opportunity cost to reading journals and learning about things that do not lead to a new grant or paying the rent. Nevertheless, I have always valued the time I spend bathing in the pure stimulation of science. A recent publication in JID stimulated me to think about parasitic diseases and their vectors (Gomes et al, 2012).
A purified sand-fly salivary gland protein was inoculated into mice and protected the mice when they were bitten by sandflies infected with Leishmania. The lymphocytes of Knock-out B-cell deficient mice lymphocytes received protection, but mice treated with anti-helper cell antibodies developed ulcerative leishmaniasis after being bitten. The protection by salivary protein inoculation was not complete, since Leishmania were present in the skin of protected mice. It has been known for about 15 years that mice bitten by sand-flies not carrying Leishmania are protected when subsequently bitten by infected sand-flies.
I doubt that this is a unique confluence of organism, vector, and host, and we can consider the described ”vaccination” to have broader protective mechanisms. Usually, vaccination is considered through the spyglass of specificity, aimed at the perfect immune response of the host. There may be other ways of skinning the infection cat that deserve contemplation; the protective response of vaccination deserves a wide-angle rather than a telescopic lens.
LJM11 the salivary protein that alters the immune response also generated antibodies that cross-react with the epithelial cell surface molecule desmoglein-1(DSG1) that is a target of of pathogenic molecules in Brazilian pemphigius foliiaceus (Qian et al, 2012). The common epitope for DSG-1 and LJM11 is conformational in nature and not determined by the amino acid sequences of the tqwo molecules. . Whether this finding has anything in common with the effect of LJM11 on lymphocytes remains to be determined.
Gomes R, Oliveira F, Teixeira C, et al (2012) Immunity to Sand Fly Salivary Protein LJM11 Modulates Host Response to Vector-Transmitted Leishmania Conferring Ulcer-Free Protection. J Invest Dermatol doi: 10.1038/jid.2012.205
Qian Y, Jeong JS, Maldonado M, et al (2012) Cutting edge:Brazilian pemphigus foliaceus anti-desmoglein I autoantibodies cross-react with Sand fly salivary LJM11 antigen. J Immunology 189:1535-1539