Vaccination against Strongyloides venezuelensis with homologue antigens using new immunomodulators.

Control of Strongyloides stercoralis infection is based on antihelminthic treatment. However, the development of an efficient vaccine is an important goal for more effectively managing this disease. Different Strongyloides spp. antigen preparations have been previously tested but without satisfactory results. In the present study, we evaluated whether the doxycholic acid extract of Strongyloides venezuelensis stage 3 larvae was able to protect CD1 mice against a homologue infection. Moreover, we included saponins from Quillaja saponaria (Qs) and immunomodulatory substances, i.e., Phlebodium pseudoaureum hydroalcoholic extract (PAL) or the amino alcohol AA0029, which has an aliphatic chain of 14 carbon atoms with a hydrophilic amino alcohol head, where the amino group is protected with a butoxycarbonyl group. The DOCSv antigen, together with the adjuvant components, was emulsified in a non-mineral water/oil emulsion. We performed duplicate experiments with each of the 2 immunomodulators. The DOCSv antigen used with Qs+PAL induced high levels of protection in terms of fecal egg count reduction (93.2-99.4%), 86-88% in adult worm recovery, and reduction in swelling of the small intestine. Mice vaccinated with the DOCSv antigen, together with Qs+AA0029, showed a 73.7-97.0% reduction in fecal egg count, with reduction in inflammation of the small intestine. High levels of IgG and IgG2a were observed in mice vaccinated with Qs+AA0029+DOCSv, indicating a Th1 immune response. Also, vaccinated mice recognized bands of 34, 39, 43, 95, and 170 kDa in a Western blot.

Induction of immunity by transcolostrally-passed Strongyloides ransomi larvae in neonatal pigs.

Earlier studies had suggested that neonatal pigs that acquire infections of Strongyloides ransomi via the sow's milk fail to expel intestinal worms normally. Adult worm recoveries were compared from the intestines of normal and transcolostrally-infected neonatal pigs after a subcutaneous challenge inoculation of third-stage larve (L3) to determine whether a direct intestinal infection (via sow's colostrum) might affect resistance. Additionally, transcolostrally-infected pigs that had received an additional subcutaneous inoculation of L3 were reinoculated with L3, and the adult worm recoveries were compared to those of pigs immunized with only one subcutaneous inoculation of L3 to determine the effect of initial transcolostral infection on the development of protective immunity by this established procedure. The results showed that intestinal worms obtained transcolostrally can induce high resistance in pigs to reinfection by S. ransomi, and they do not affect the enhancement of protective immunity by a subcutaneous inoculation of L3. However, peripheral blood lymphocytes obtained from transcolostrally-infected pigs did not respond to larval antigens in vitro until after a subsequent subcutaneous inoculation of L3.