Early infections by myxoma virus of young rabbits (Oryctolagus cuniculus) protected by maternal antibodies activate their immune system and enhance herd immunity in wild populations.

Stéphane Marchandeau,Jacky Aubineau,Alain Roobrouck,Brigitte Peralta,Dominique Pontier,David Fouchet,Stéphane Bertagnoli,Jean-Sébastien Guitton,Francis Berger,Yves Léonard,Jérôme Letty,Jacqueline Gelfi

doi:10.1186/1297-9716-45-26

Abstract

The role of maternal antibodies is to protect newborns against acute early infection by pathogens. This can be achieved either by preventing any infection or by allowing attenuated infections associated with activation of the immune system, the two strategies being based on different cost/benefit ratios. We carried out an epidemiological survey of myxomatosis, which is a highly lethal infectious disease, in two distant wild populations of rabbits to describe the epidemiological pattern of the disease. Detection of specific IgM and IgG enabled us to describe the pattern of immunity. We show that maternal immunity attenuates early infection of juveniles and enables activation of their immune system. This mechanism associated with steady circulation of the myxoma virus in both populations, which induces frequent reinfections of immune rabbits, leads to the maintenance of high immunity levels within populations. Thus, myxomatosis has a low impact, with most infections being asymptomatic. This work shows that infection of young rabbits protected by maternal antibodies induces attenuated disease and activates their immune system. This may play a major role in reducing the impact of a highly lethal disease when ecological conditions enable permanent circulation of the pathogen.

Highlights

A same infectious agent may induce in vertebrates a large range of clinical signs from asymptomatic to a severe disease that may even lead to death
Maternal immunity may have long-term effects: even in the absence of early infection, individuals born with maternal antibodies may display an enhanced immune response when infection occurs after maternal immunity has waned [23,24,25]
Maternal immunity may even have positive trans-generational effects on offspring of females having received maternal antibodies from their own mother [25]. Most of these studies on maternal immunity have focused on the individual level but little is known about the potential effect of maternal immunity on disease dynamics and impact at the population level

Summary

Introduction

A same infectious agent may induce in vertebrates a large range of clinical signs from asymptomatic to a severe disease that may even lead to death. Several studies have demonstrated that maternal antibodies block the infection in the case of an early exposure to the parasite and inhibit the offspring immune response [12]. This blocking effect is responsible for unsuccessful vaccination in newborns [13,14,15]. Maternal immunity may even have positive trans-generational effects on offspring of females having received maternal antibodies from their own mother [25] Most of these studies on maternal immunity have focused on the individual level but little is known about the potential effect of maternal immunity on disease dynamics and impact at the population level

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Conclusion