ype="table"}). The two markers analyzed had intermediate allelic frequencies, with MAF close to 0.40 ([Table 4](#viruses-11-00706-t004){ref-type="table"}). The odds ratios of aborting versus not aborting during an outbreak were 2.3 to 4 times greater in sows of the rs325981825 GG genotype than in the other genotypes ([Table 5](#viruses-11-00706-t005){ref-type="table"}). The probability of abortion followed an additive pattern, similar to GBP5_rs340943904, where the presence of the A allele raised the probability of abortion from 16% in GG sows to 27% and 40% in AG and AA animals, respectively ([Figure 1](#viruses-11-00706-f001){ref-type="fig"}). Given the intermediate frequencies, this marker responded better to selection than the other three favorable alleles did, which were present at a much lower frequency.

5. Conclusions {#sec5-viruses-11-00706}
==============

In conclusion, we bring here the first evidence that mutations in the host genome can predispose or protect from complete reproductive failure in sows infected with a field strain of PRRSV. Although transcriptomic and genomic scans have studied the genetic component of spontaneous abortions in pigs \[[@B41-viruses-11-00706]\] and cattle \[[@B42-viruses-11-00706]\], abortion as an outcome of an infectious disease has not been explored from a genetic point of view in pigs. The low or intermediate allelic frequency of some protective alleles and potential interactions between some of them will need to be tackled in future studies.

The authors would like to acknowledge the support and generosity of the veterinarians and farmers involved in this study.

The following are available online at <https://www.mdpi.com/1999-4915/11/8/706/s1>, Table S1: Primers and probes used in the genotyping experiment; Table S2: Primers used to sequence the *HDAC6* promoter and coding regions; Table S3: Comparison of the probability of abortion during a PRRSV outbreak by marker genotype in the sow population studied.

###### 

Click here for additional data file.

Conceptuali