Protective Effect of Humus Extract Against Trypanosoma brucei Infection in Mice

Abstract

ABSTRACT. Humic substances are formed during the decomposition of organic matter in humus, and are found in many natural environments in which organic materials and microorganisms are present. Oral administration of humus extract to mice successfully induced effective protection against experimental challenge by the two subspecies, Trypanosoma brucei brucei and T. brucei gambiense. Mortality was most reduced among mice who received a 3% humus extract for 21 days in drinking water ad libitum. Spleen cells from humus-administered mice exhibited significant non-specific cytotoxic activity against L1210 mouse leukemia target cells. Also, spleen cells produced significantly higher amounts of Interferon-γ when stimulated in vitro with Concanavalin A than cells from normal controls. These results clearly show that administration to mice of humus extract induced effective resistance against Trypanosoma infection. Enhancement of the innate immune system may be involved in host defense against trypanosomiasis.

Protection against Flavobacterium psychrophilum Infection (Cold Water Disease) in Ayu Fish (Plecoglossus altivelis) by Oral Administration of Humus Extract

“…The survival rates of the humustreated groups were significantly higher than in the untreated control fish group. The survival rate of fish receiving 10% of humus extract was lower than in groups treated with 5 or 1%, implying an optimal concentration for administration of the extract to animals as we reported previously [8]. In the present study, no F. psychrophilum was re-isolated from fish after the challenge, but A. hydrophila (rather than F. psychrophilum) was isolated from part of the fish, indicating changes of the bacterial population during the progression of skin lesions [7].…”

“…In previous studies we demonstrated the protective effect of humus extract against ulcer disease in carp (caused by atypical Aeromonas salmonicida) [7], experimental trypanosomiasis in mice [8], and anti-tumor effect in mice [6]. The humus extract showed its effect when administered orally to animals with food or drinking water.…”

“…The fish were fed pellets containing humus extract twice daily (total 2% of fish body weight per day) for 30 days prior to challenge by F. psychrophilum, and for the 21 days immediately after bacterial challenge. The concentrations of humus extract adopted in the present study were selected according to the effective concentrations obtained in the previous experiments [6][7][8]. Control fish were fed the dry pellet without humus extract.…”

Expression of HPV6b L1/EBV LMP2 multiepitope and immunogenicity in mice

“…Two weeks after the third immunization, blood samples collected from the orbital sinus of individual mouse were used to determine antibody responses. Spleen removed from the sacrificed mice was then used for preparing T lymphocytes for cytotoxic assays [22].…”

Immune response of mice to a latency membrane protein 2 multiepitope antigen of Epstein-Barr virus applied as DNA vaccine and/or peptide vaccine

“…Single lymphocyte suspensions from spleen were prepared for cytotoxic assay (Kodama et al, 2008). The cytotoxic activity of T lymphocytes was determined by lactate dehydrogenase (LDH) release assay using CytoTox 96w nonradioactive cytotoxicity assay (Promega, USA).…”