Brugia pahangi: in vivo tissue migration of early L3 alters gene expression.

Events occurring during early filarial nematode migrations are central to parasite establishment but rarely studied. Brugia pahangi larvae injected intradermal (ID) into the hind limb of the gerbil (Meriones unguiculatus) can be recovered from the popliteal lymph node (POP) at 3 days post-infection (DPI). They have been designated migrating larvae (IDL3). Alternatively, L3 recovered at 3DPI from the peritoneal cavity (IPL3) do not migrate. Subtracted cDNA libraries using IDL3 and IPL3 revealed distinct gene profiles between IDL3 and IPL3. Troponin-c was significantly upregulated in IDL3, while Cathepsin L was significantly increased in IPL3. Differences in mRNA levels were also observed with these and other genes between IDL3, IPL3 and L3 isolated from mosquitoes (VL3). These data suggest that migratory activity, exposure to potentially different host environments and/or host location may be important external factors in influencing larval gene expression.