Background: Infection with the protozoanToxoplasma gondiicauses serious public health problems and is of great economic importance worldwide. Protection from acute toxoplasmosis is known to be mediated by CD8+ T cells, but theT. gondiiantigens and host genes required for eliciting protective immunity have been poorly defined. TheT. gondiidense granule protein 6 (GRA6), recently proved to be highly immunogenic and produces fully immune protection inT. gondiiinfected BALB/c mice with an H-2L^dgene. The CD8+ T cell response of H-2L^dmice infected by theT. gondiistrain seemed to target entirely to a single GRA6 peptide HF10-H-2L^dcomplex.Results: To determine whether a GRA6-based DNA vaccine can elicit protective immune responses toT. gondiiin BALB/c mice, we constructed a eukaryotic expression vector pcDNA3.1-HisGRA6 and tested its immunogenicity in a mouse model. BALB/c mice were vaccinated intramuscularly with three doses of GRA6 DNA and then challenged with a lethal dose ofT. gondiiRH strain tachyzoites. All immunized mice developed high levels of serum anti-GRA6 IgG antibodies, andin vitrosplenocyte proliferation was strongly enhanced in mice adjuvanted with levamisole (LMS). Immunization with pcDNA3.1-HisGRA6 with LMS resulted in 53.3% survival of challenged BALB/c mice as compared to 40% survival of BALB/c without LMS. Additionally, immunized Kunming mice without an allele of H-2L^dfailed to survive.Conclusions: Our result supports the concept that the acquired immune response is MHC restricted. This study has a major implication for vaccine designs using a single antigen in a population with diverse MHC class I alleles.

Artificial insemination (AI) has been used globally as a routine technology in the swine production industry. However, genetic parameters and genomic prediction accuracy of semen traits have seldom been reported. In this study, we estimated genetic parameters and conducted genomic prediction for five types of sperm morphology abnormalities in a large Duroc boar population. The estimated heritability of the studied traits ranged from 0.029 to 0.295. In the random cross-validation scenario, the predictive ability ranged from 0.212 to 0.417 for genomic best linear unbiased prediction (GBLUP) and from 0.249 to 0.565 for single-step GBLUP (ssGBLUP). In the forward prediction scenario, the predictive ability ranged from 0.069 to 0.389 for GBLUP and from 0.085 to 0.483 for ssGBLUP. In conclusion, the studied sperm morphology abnormalities showed moderate to low heritability. Both GBLUP and ssGBLUP showed comparative predictive abilities of breeding values, and ssGBLUP outperformed GBLUP under many circumstances in respect to predictive ability. To our knowledge, this is the first time that the genetic parameters and genomic predictive ability of these traits were reported in such a large Duroc boar population.