The behavior and pathogenicity ofToxacara canis larvae in mice of different strains

Abstract

In the present study the behavior and pathogenicity of second-stage larvae of Toxocara canis were examined in different mouse strains with special emphasis on the major histocompatibility complex (MHC). Mice of the inbred strains BALB, C3H, C57BL, and DBA and the outbred strain NMRI were infected orally with 1000 second-stage larvae of T. canis. The clinical behavior of the animals; the numbers of larvae detected in the liver, lungs, brain, and musculature; the hematological and serological parameters; and histological sections were examined. In mice of the BALB strain, no death occurred during the entire period of the investigation and the pattern of body-weight development of infected and uninfected animals was almost identical. The highest larval counts in the brain of all strains were found in BALB mice. The percentage of eosinophils in the blood of BALB mice increased after the 8th week postinfection, whereas it decreased in the other strains. Histological and pathophysiological changes developed to a lesser extent in this strain than in the other strains. In mice of the strains C3H, C57BL, DBA, and NMRI, deaths occurred from the 4th week postinfection onward. The infected animals lost weight in comparison with the uninfected controls; the number of larvae found in the brains of infected mice of the above-mentioned strains were lower than those detected in the BALB strain. There is no evidence that mechanical damage caused by migrating larvae in the brain tissue is mainly responsible for symptoms of central nervous toxocariasis. Likewise, the assumption that the MHC is involved in the allergic-inflammatory response in the brain could not be proven: infected mice of the BALB and DBA strains reacted completely differently, although both are equipped with the same MHC haplotype.

Muscular strength decrease in Rattus norvegicus experimentally infected by Toxocara canis

“…Recently it was observed the presence of 3 rd stage larvae of T. canis in muscles of R. norvegicus from the 5 th at least the 60 th day after experimental infection with embryonated eggs of this ascarid and predominantly between the 10 th and the 30 th days after infection 10 , showing a migration larvae pattern similar of that found in other rodent species 1,8 ; corroborating the possibility of T. canis larval transference to carnivore animals by prey-predator relationship. On the other hand, there are some indications of muscle changes in humans infected by T. canis, resulting in the emergence of antistriational antibodies, suggesting the occurrence of anti-muscle autoimmune response 11 .…”

The significance of cerebral toxocariasis: a model system for exploring the link between brain involvement, behaviour and the immune response

“…Epe and colleagues infected four inbred strains of mice and one outbred strain and reported the presence of Toxocara larvae in the brains of all mice over the infection period, with the inbred BALB/c mice demonstrating the highest burdens (Epe et al, 1994). Investigating behaviour in inbred strains of mice is attractive as any infection-induced behavioural alterations that could be masked in heterogeneous outbred mice may appear more pronounced.…”

“…BALB/c mice were selected as the susceptible strain and NIH mice were deemed to be resistant. The choice of strains was supported by previous studies where BALB/c mice have been reported to be more susceptible to T. canis infection (Bardón et al, 1994;Epe et al, 1994) and NIH mice demonstrated a higher resistance to T. canis infection than outbred CD1 mice (Abo-Shehada and Herbert, 1989). Recently, Kolbeková and colleagues demonstrated an accelerated speed of migration to the brain in re-infected BALB/c mice (Kolbeková et al, 2011).…”

Isotype specific immune responses in murine experimental toxocariasis

“…This results might indicate that somatic products released from the dead larvae are responsible for IgG1 production observed in the C3H strain. However, Epe et al (1994) examined the behaviour and pathogenicity of second-stage larva (L2) of T. canis in different mouse strains. The highest larval counts in the brain of all strains were found in BALB mice.…”