MHC-genotype of progeny influenced by parental infection

Abstract

In a previous series of in vitro fertilization experiments with mice we found non-random combination of major histocompatibility complex (MHC) haplotypes in the very early embryos. Our results suggested that two selection mechanisms were operating: (i) the eggs selected speci¢c sperm; and (ii) the second meiotic division in the eggs was in£uenced by the type of sperm that entered the egg. Furthermore, the proportion of MHC-heterozygous embryos varied over time, suggesting that non-random fertilization was dependent on an external factor that changed over time. As a higher frequency of heterozygous individuals correlated with an uncontrolled epidemic by MHV (mouse hepatitis virus), we suggested that MHV-infection might have in£uenced the outcome of fertilization. Here, we present an experiment that tests this hypothesis. We infected randomly chosen mice with MHV and sham-infected control mice ¢ve days before pairing. We recovered the two-cell embryos from the oviduct, cultured them until the blastocyst stage, and determined the genotype of each resulting blastocyst by polymerase chain reaction. We found the pattern that we expected from our previous experiments: virus-infected mice produced more MHC-heterozygous embryos than sham-infected ones. This suggests that parents are able to promote speci¢c combinations of MHC-haplotypes during fertilization according to the presence or absence of a viral infection.

Sexual selection for genetic compatibility: the role of the major histocompatibility complex on cryptic female choice in Chinook salmon (Oncorhynchus tshawytscha)

“…Thus, the observed mate compatibility, which explains roughly 44% of the variation in sperm velocity (42-45% across models), appears to be characterized by factors other than MHC, potentially by other peptides identified in the ovarian fluid of Chinook salmon (Johnson et al, 2014). MHC-dependent fertilization success was reported in mice (Wedekind et al, 1996;Rülicke et al, 1998) and the red jungle fowl (Løvlie et al, 2013), but the mechanisms by which such a non-random gamete fusion occurs are yet unknown. In this study, we observed an MHC class II-based fertilization success, but our data suggests that this bias is achieved via mechanisms other than MHC-based sperm velocity in ovarian fluid.…”

“…Potentially, MHC-dependent CFC could also arise after the sperm has entered the egg and before the pronucleus fusion (Yeates et al, 2009). MHC-based CFC was uncovered in the red jungle fowl (Løvlie et al, 2013) and in vitro fertilization experiments in MHC-congenic mice revealed an MHC-dependent gamete fusion (Wedekind et al, 1996;Rülicke et al, 1998).…”

The evolutionary ecology of the major histocompatibility complex

“…A number of adaptive hypotheses, which are not necessarily mutually exclusive, have been proposed to explain how MHC could influence mating behaviour and reproductive success. Those that have received most attention are: (1) MHC-related selective fertilisation (Wedekind et al, 1996;Rulicke et al, 1998;Wedekind et al, 2004); (2) MHC-dependent selective abortion (Alberts and Ober, 1993); (3) disassortative matings based on MHC genotype (Penn and Potts, 1999). Here, we focus on the latter, as this has been the primary focus for studies in non-model vertebrates.…”

MHC-based patterns of social and extra-pair mate choice in the Seychelles warbler

“…Under a good-genes model, if females preferentially mate with superior-condition males that are relatively disease resistant, they may provide their offspring with 'good' MHC haplotypes associated with improved resistance to pathogens within the current environment, or avoid 'bad' MHC haplotypes associated with deleterious effects (Abplanalp et al 1992;Wedekind et al 1996;Rulicke et al 1998). In this scenario, males with a greater diversity of MHC alleles should, through either heterozygote advantage or from an increased chance of having specific resistant alleles, be in better condition and, therefore, be preferred by females.…”