Evaluation of crude adult Ascaris suum intestinal tract homogenate in inducing protective IgG production against A. suum larvae in BALB/c mice.

Globally, ascariasis ranks as the second leading intestinal helminth infection. However, progress in developing better control strategies, such as vaccines, remains slow-paced. This study aims to measure antibody production and parasite load in male BALB/c mice immunized with crude Ascaris suum intestinal tract homogenate. Thirty-two (32) mice were randomized into: (1) unvaccinated, uninfected (UU); (2) unvaccinated, infected (UI); (3) vaccinated, uninfected (VU); and (4) vaccinated, infected (VI) groups. A 100-μL vaccine containing 50 μg of homogenized A. suum intestines and Complete Freund's Adjuvant (1:1) were introduced intraperitoneally. Immunizations were done on days 0, 10, and 20. Oral gavage with 1000 embryonated eggs was done on day 30. Blood was obtained at day 40. To measure serum IgG levels, indirect ELISA was done. Microtiter plates were coated with 100 μg larval homogenate, and HRP-conjugated anti-mouse IgG was used as secondary antibody. Parasite load was measured in lung and liver tissues. Tukey's HSD of signal to cut-off ratios of absorbance readings obtained in indirect ELISA procedure for the 1:200 serum dilution showed statistically significant difference between the UU and VI (p = 0.026) as well as between UI and VI (p = 0.003) groups. No statistically significant difference in parasite load was observed in the lungs (p = 0.074), liver (p = 0.130), and both lungs and liver (p = 0.101). Immunization elicited a significant larva-directed IgG production. However, there is no significant difference in parasite loads in either lung or liver tissues across all treatment groups as the larval counts obtained from the study were very low and may not be indicative of the actual parasite load in mice.