Immune response to fleas in a wild desert rodent: effect of parasite species, parasite burden, sex of host and host parasitological experience

Abstract

SUMMARY We studied immune responses of the jird Meriones crassus to different flea species belonging to the same family. We used jirds maintained in an outdoor enclosure (enclosure; N=18) and parasitized by fleas Xenopsylla conformis mycerini and Xenopsylla ramesis, and also jirds born in the laboratory to previously parasitized mothers(laboratory animals; N=23). We asked (i) whether cross-immunity to different fleas occurs, (ii) whether there is a sex difference in immune responses to flea parasitism and (iii) whether the severity of the immune responses depends on parasite load. In the enclosure animals, immune response to antigen from the unfamiliar flea Synosternus cleopatrae pyramidisdid not differ from those to antigens from the familiar fleas. In contrast,laboratory rodents demonstrated no difference in the immune response between S. c. pyramidis antigen and either the phytohemagglutinin treatment or controls, although their responses to antigens of fleas familiar to their mothers (X. c. mycerini and X. ramesis) were significantly higher than those to antigen of S. c. pyramidis and phytohemagglutinin. The results clearly demonstrated that (i) cross-reactivity in rodent responses to different flea species occurred for enclosure but not for laboratory jirds and (ii) immune-naïve animals whose mothers were parasitized by fleas had some degree of immunity against fleas. The only sex difference in immunological parameters was the higher level of circulating immune complexes in females than in males. Only phagocytic activity was affected by flea burden, decreasing with an increase in flea numbers.

Is the feeding and reproductive performance of the flea,Xenopsylla ramesis, affected by the gender of its rodent host,Meriones crassus?

“…Khokhlova complexes than males (Khokhlova et al, 2004). This indicates a higher synthesis of antibodies and clearance of the antigen through complexation in females.…”

“…Two weeks prior to experiments, each animal was exposed three times to 30 (10 males and 20 females) fleas (Xenopsylla ramesis Rothschild) once every two days, for 2 h each time. This was done to allow rodents to develop similar degrees of acquired resistance against fleas (see Khokhlova et al, 2004). The strongest host response to flea bites was reported to occur 7-14 days after flea feeding began (Hudson at al., 1960), although this period can probably be characterized by rapid changes and, therefore, relatively low stability of immune system function.…”

Reproductive success in two species of desert fleas: density dependence and host effect

“…Average body mass of an adult M. crassus is about 80·g, whereas that of an adult G. dasyurus is about 22·g. In addition, M. crassus possesses 'pre-invasive' immune responses against fleas and maintains a certain degree of immunological 'readiness' (Khokhlova et al, 2004b), whereas G. dasyurus mounts the immune response against fleas only after being attacked (Khokhlova et al, 2004a). Consequently, we predict that negative relationship between reproductive parameters and density will be manifested in G. dasyurus more so than in M. crassus.…”

Differential Influence of Seabuckthorn on the In vivo and In vitro Cell-Mediated Immune Responses in Chickens with Gumboro Disease

“…Wattle thickness was measured before and 24, 48 and 72 hours post injection and rejection indices were calculated as a percentage of the measurements. Leukocyte blast transformation test 12 . An in vitro blast transformation test was carried out on heparinized blood using the sea-buckthorn extract in whole blood cultures.…”