We proposed a parsimonious hypothesis for the dynamics of the rabbit–nematode system where the seasonal dynamics of T. retortaeformis were driven primarily by the host acquired immune response affecting helminth development and fecundity (10,14,15), while G. strigosum was not constrained by immunity, so that parasite abundance increased exponentially

click here with host age (11). Previous studies supported the hypothesis of an immune-regulated T. retortaeformis infection and noted that third-stage larvae may enter arrested development under adverse immunological conditions (16). The tendency to arrest the development in the mucosa and the evidence of intestinal pathology were more recently confirmed in laboratory experiments (17,18). Laboratory infections of rabbits with G. strigosum showed a clear increase in serum

IgG but this was not sufficient to clear the infection, and high intensities were still observed 3 months after the initial challenge (19). Epacadostat in vivo No clinical symptoms but chronic asthenic gastritis were also reported in rabbits exposed to different infection doses (20). Overall, these studies indicate that rabbits develop different immune responses against T. retortaeformis and G. strigosum, which can explain the different patterns of infection observed in free-living rabbit populations. The identification of the processes affecting host–parasite interactions can be challenging in natural animal systems if more than one mechanism is taking place and, even more, when there are confounding variables that

cannot be ruled out (10,21). Motivated by our epidemiological work and to gain a better understanding of the immuno-parasitological mechanisms influencing the interaction between the host and its parasites, we undertook a comprehensive study to quantify changes in the rabbit’s immunological components and associated helminth intensities, during a primary infection of T. retortaeformis and G. strigosum. Laboratory infections were performed, wherein rabbits were challenged with third-stage larvae (L3) and the dynamics of the systemic and local immune response quantified for 120 days post-challenge. Our prediction was that the immune response to the two helminths differed fundamentally in the intensity but not the about type of components activated, so that T. retortaeformis would elicit a stronger response than G. strigosum, and this would lead to the clearance of the first but not the second nematode. The ultimate goal of this study was twofold: first, to identify the most common immunological processes and essential components affecting the epidemiology of these gastrointestinal infections and second, to highlight the immunological differences between these helminths and discuss how they can explain the epidemiology of infection in free-living rabbit populations. Trichostrongylus retortaeformis and G.