Giardia duodenalis: Kinetics of cyst elimination and the systemic humoral and intestinal secretory immune responses in gerbils (Meriones unguiculatus) experimentally infected

• Published in: Experimental parasitology Vol. 125; no. 3; pp. 297 - 303
• Main Authors: Amorim, R.M.R., Silva, D.A.O., Taketomi, E.A., Morato, M.G.V.A., Mundim, M.J.S., Ribeiro, D.P., Oliveira, T.C., Viana, J.C., Gomes, M.A., Cury, M.C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.07.2010; Elsevier
• Subjects: Animals; Antibodies, Protozoan - biosynthesis; Antibodies, Protozoan - blood; Biological and medical sciences; Feces - chemistry; Feces - parasitology; Female; Fundamental and applied biological sciences. Psychology; Gerbillinae; Giardia duodenalis; Giardia lamblia - immunology; Giardiasis - immunology; Immune response; Immunoglobulin A, Secretory - analysis; Immunoglobulin A, Secretory - biosynthesis; Immunoglobulins - biosynthesis; Immunoglobulins - blood; Kinetics; Life cycle. Host-agent relationship. Pathogenesis; Male; Meriones unguiculatus; Protozoa; Specific Pathogen-Free Organisms; Trophozoites - immunology; Meriones unguiculatus; Immune response; Giardia duodenalis; Protozoa; Rodentia; Elimination; Parasite; Diplomonadida; Organism defense; Systemic; Vertebrata; Mammalia; Cyst; Gerbil
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2010.02.007

This study aimed to determine the pre-patent period and to evaluate the kinetics of cyst elimination and the systemic humoral (IgA, IgG1, IgG2a, IgM, IgE) and intestinal secretory (IgA) immune responses in gerbils (Meriones unguiculatus) experimentally innoculated with different doses of Giardia duodenalis trophozoites. Forty-eight animals aged 6–8weeks were used, equally distributed among six groups, five groups innoculated with different doses of trophozoites (101, 102, 103, 104, 105) and one control (non-infected) group. Coproparasitological examinations were carried out daily up to 91days after inoculation (d.a.i.) to determine the pre-patent period and the kinetics of cyst elimination. Blood and stool samples were weekly collected for antibody assays. The pre-patent period was observed from the 9 d.a.i. onwards, with intermittent elimination of variable quantities of cysts up to 27 d.a.i.. All infected gerbils, irrespective of the dose received, were able to mount systemic humoral immune responses as evidenced by specific IgM titers from 7 to 28 d.a.i., corresponding to the peak of cyst elimination, followed by high and persistent IgG1 titers. Intestinal secretory responses were also seen with two peaks of fecal IgA titers, corresponding to IgM and IgG1response peaks, respectively. In conclusion, systemic and intestinal humoral immune responses were related to the control of giardiasis in this experimental model.