Abstract
Maternal antibodies protect chicks from infection with pathogens early in life and may impact pathogen dynamics due to the alteration of the proportion of susceptible individuals in a population. We investigated the transfer of maternal antibodies against avian influenza virus (AIV) in a key AIV host species, the mallard (Anas platyrhynchos). Combining observations in both the field and in mallards kept in captivity, we connected maternal AIV antibody concentrations in eggs to (i) female body condition, (ii) female AIV antibody concentration, (iii) egg laying order, (iv) egg size and (v) embryo sex. We applied maternity analysis to the eggs collected in the field to account for intraspecific nest parasitism, which is reportedly high in Anseriformes, detecting parasitic eggs in one out of eight clutches. AIV antibody prevalence in free-living and captive females was respectively 48% and 56%, with 43% and 24% of the eggs receiving these antibodies maternally. In both field and captive study, maternal AIV antibody concentrations in egg yolk correlated positively with circulating AIV antibody concentrations in females. In the captive study, yolk AIV antibody concentrations correlated positively with egg laying order. Female body mass and egg size from the field and captive study, and embryos sex from the field study were not associated with maternal AIV antibody concentrations in eggs. Our study indicates that maternal AIV antibody transfer may potentially play an important role in shaping AIV infection dynamics in mallards.
Highlights
Maternal antibodies provide protection against pathogens in the early stages of a chick’s life [1]
In yellow-legged gulls (Larus michahellis), 81% of females had circulating avian influenza virus (AIV) antibodies and 51% of their eggs received these antibodies maternally [11]. In this species it was shown that maternal AIV antibodies in eggs reflected the circulating AIV antibodies of the laying females, and that the first-laid eggs received highest levels of maternal antibodies [12]. These findings in gulls indicate a considerable transfer of maternal AIV antibodies to eggs, raising the possibility that maternal antibody transfer might play a vital role in AIV infection dynamics in other host species
Only female AIV antibody concentration was correlated with AIV antibody concentration in egg yolk (Table 1): high antibody concentrations in females corresponded with high concentrations in eggs (Figure 1A)
Summary
Maternal antibodies provide protection against pathogens in the early stages of a chick’s life [1]. Maternal antibodies can be of crucial importance for a chick’s initial humoral defence and growth rate, potentially increasing its survival during the early stages of its life (for review see [6]). These maternal antibodies can have considerable impact on pathogen dynamics at the population level, reducing the proportion of susceptible individuals in a host population [1]. These findings in gulls indicate a considerable transfer of maternal AIV antibodies to eggs, raising the possibility that maternal antibody transfer might play a vital role in AIV infection dynamics in other host species
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