Relationship between infective dose of larvae on pathology and antibody response in experimental toxocarosis in mice
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Date
2019-12
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Abstract
Toxocara canis, a cosmopolitan parasite of canines and the major causative agent
of human toxocariasis, constitutes a serious epidemiologic problem in many countries.
In the present study, the dynamics of IgG antibody production, larval distribution and
pathological changes were evaluated after experimental infection of BALB/c mice with
two doses of embryonated eggs of T. canis. The mice were divided into 3 groups; Group
I, infected with 100 eggs; Group II, infected with 1000 eggs and Group III, uninfected
control mice. The mice were bled at 0, 7, 14, 28, 45, 60, 90, 120 and 150 days post infection
(dpi). Indirect ELISA was performed for detecting IgG antibody response. On each date,
one mouse from each group was sacrificed for larval recovery from lung, liver, brain,
eye and musculature and for histopathology. The IgG antibodies in both the infected
groups were detected from 7 dpi which increased gradually and peak at 60 dpi. After,
90 dpi, the IgG antibody response began to decline but it was detected until the end of
the experiment. The IgG antibody response of group II mice was significantly higher
than the group I mice throughout the observation period. Statistically highly significant
difference was observed between the infected groups (P<0.01) from 7-150 dpi. These
results showed that the magnitude of the anti-Toxocara antibody response was directly
proportional to the dose of the inocula. In the lung and liver, larvae were found in both
the infected groups from 7 to 21 dpi where as in the brain and musculature, these were
recovered in both the groups from 7 to 150 dpi. The group inoculated with 1000 eggs
showed a greater number of larvae in the brain. It was found that the degree of larval
recovery was dependent on the size of the infecting dose. Histopathological examination
revealed inflammatory infiltrate and haemorrhages in the lung and liver parenchyma
from 7 to 60 dpi of both the infected groups except brain. Granulomas were seen around
the larvae in the section of lung and liver from 28 to 60 dpi. However, in the section of
brain, the larvae were seen from 14 to 150 dpi but in the eye, the larva was seen from 90
and 120 dpi without inflammatory reaction surrounding the larvae.
Description
TNV_JVP_2019_33(2)13-23
Keywords
Veterinary Science