Jina Kook

Pathogenicity and lethality of a minute intestinal fluke, Neodiplostomum seoulense, to various strains of mice.

Pathogenicity and lethality of Neodiplostomum seoulense to various strains of mice (mast cell-deficient W/Wv, their normal littermate +/+, C57BL/6, BALB/cA, C3H/HeJ), and a hybrid (BALB/cA x C3H/HeJ)F1 were investigated. When the mice were infected orally each with 200 metacercariae, their abdomen became distended, and all mice died by day 23 postinfection (PI) except BALB/cA, which were severely weakened but recovered after 28 days. Even a smaller infection dose of 25 metacercariae was highly lethal to C3H/HeJ mice. Despite treatment with praziquantel (3 mg/mouse) on day 10 PI, 80% of C57BL/ 6 mice did not recover and died. After day 14 PI, the whole intestine of C57BL/6 mice was contracted and significantly shortened in length, and charcoal meal transit was significantly faster compared with uninfected controls. After incubation in papaverine, the contracted intestines of C3H/HeJ mice did not relax, suggesting that the change is irreversible. In conclusion, N. seoulense has the potential to kill most strains of mice by causing irreversible damage to their intestine. The effects of mucosal mast cells on the survival rate of mice were negligible, because both W/Wv and +/+ mice died around day 20 PI.

Suppressed Cytokine and Immunoglobulin Secretions by Murine Splenic Lymphocytes Infected In Vitro with Toxoplasma gondii Tachyzoites

Mechanisms of host immunosuppression after infection with Toxoplasma gondii are unclear. This study was performed to observe cytokine and immunoglobulin secretions by murine splenic lymphocytes infected in vitro with live, nonreplicating (irradiated) RH tachyzoites on stimulation with concanavalin A (Con A) or lipopolysaccharide (LPS). For lymphocyte cultivation, 3 groups were prepared: coculture with live nonirradiated tachyzoites separated by a transwell (group T), live irradiated tachyzoites without a transwell (group R), and no tachyzoites (group C). Compared with group T, groups R and C, on stimulation with Con A, revealed significantly (P < 0.05) lower levels of interleukin-2 (IL-2) and IFN-γ, but not IL-10. The levels of IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM were also significantly (P < 0.05) lower in groups R and C than in group T after stimulation with LPS. The results suggest that intracellular infection of murine splenic lymphocytes with T. gondii tachyzoites could impair their capacity to produce cytokine and immunoglobulin secretions.

Migration of Neodiplostomum Leei (Digenea:Neodiplostomidae) neodiplostomula to the livers of various mammals

Of morphologically indistinguishable small-sized neodiplostomula in the grass snake Rhabdophis tigrina in the Republic of Korea, some, such as Neodiplostomum seoulense, mature into adults in the intestines of rodents, whereas others, such as Neodiplostomum leei, migrate to rodent livers and mature in the intestines of chicks. In the present study, we aimed to observe in more detail the extraintestinal migration and development of N. leei by using various animal models, i.e., mice, rats, hamsters, rabbits, cats, and chicks. In mammals, small-sized neodiplostomula (N. leei) inoculated orally penetrated the intestinal wall, entered the peritoneal cavity, and oriented to the liver without passing through any other organ. In rodent livers, the neodiplostomula were surrounded by host inflammatory cells and fibrotic tissues from day 10 postinfection (PI); the worms were found dead by day 56 PI. When neodiplostomula from rodent livers were transferred orally to mammals, they reoriented to the liver, although they were able to develop into adults in the chick intestine by day 6–7 PI. The possibility of human infections, i.e., liver migration, by N. leei neodiplostomula, among snake consumers, warrants investigation.