immunology of infectious and parasitic diseases - XXXVII Congress ...

HUMORAL IMUNE RESPONSE OF BALB/C AND C57BL/6 CHRONICALY
INFECTED MICE AGAINST HSP70 OF Toxoplasma gondii
PAULO VICTOR CZARNEWSKI BARENCO 1 ; JAIR PEREIRA CUNHA
JÚNIOR 2 ; ELAINE VICENTE LOURENÇO 3 ; MARIA CRISTINA ROQUE-
BARREIRA 3 ; DEISE APARECIDA OLIVEIRA SILVA 2 ; JOSÉ ROBERTO
MINEO 2 ; NEIDE MARIA SILVA 1
1
Laboratório de Imunopatologia, ICBIM, Universidade Federal de Uberlândia,
Uberlândia, MG;
2
Laboratório de Imunoparasitologia, ICBIM, Universidade Federal de
Uberlândia, MG;
3
Laboratório de Glicobiologia, Faculdade de Medicina de Ribeirão Preto, USP,
Ribeirão Preto, SP;
Introduction: Toxoplasma gondii is an obligate protozoan parasite widely
distributed that may cause severe damages mainly in the central nervous
system (CNS) of immunocopromised hosts, among them HIV positive patients
and pregnant women. During its life cycle, T. gondii converts from tachyzoite to
bradyzoite stage and express the T.g.HSP70. The objective of this study was to
correlate the humoral immune response against T.g.HSP70, tissue pathology
and parasite load of infected mice.
Methods and Results: BALB/c and C57BL/6 mice were intraperitoneally
inoculated with 10 cysts of ME-49 T. gondii strain and sacrificed on 7 th (group
7doi), 32 th (32doi), and 56 th days of infection (56doi). Another additional group
was infected and treated for 24 days with dexamethasone (DXM) in drinking
water from 32 th to 56 th days of infection and then sacrificed (56doi DXM). During
treatment time, the mice were observed daily for the morbidity score. C57BL/6
and BALB/c loses weight and increased the morbidity score when treated with
the drug. The sera were analyzed by ELISA for detection of IgG antibodies
against T.g.HSP70. BALB/c mice produced higher titers of IgG antibodies
against T.g.HSP70 than C57BL/6 mice, although when both lineages were
treated with DXM, low antibodies titers against T.g.HSP70 were detected. The
C57BL/6 presented more severe tissue damage and parasite load in the course
of infection than BALB/c mice. However, DXM-treated and infected mice
presented lower tissue damage than untreated mice (56doi group).
Conclusion: These data suggests that the detection of IgG antibodies against
T.g.HSP70 is an alternative diagnostic tool for toxoplasmosis in resistant mice
lineages.
Finantial support: FAPEMIG, CNPq and CAPES