CD8+ T cell-based strong selective pressure on multiple simian immunodeficiency virus targets in macaques possessing a protective MHC class I haplotype

The DRB3 gene of the bovine major histocompatibility complex: discovery, diversity and distribution of alleles in commercial breeds of cattle and applications for development of vaccines

The bovine Major Histocompatibility Complex (MHC), also known as the Bovine Leucocyte Antigen (BoLA) complex, is the genomic region that encodes the most important molecules for antigen presentation to initiate immune responses. The first evidence of MHC in bovines pointed to a locus containing 2 antigens, one detected by cytotoxic antiserum (MHC class I) and another studied by mixed lymphocyte culture tests (MHC class II). The most studied gene in the BoLA region is the highly polymorphic BoLA-DRB3, which encodes a β chain with a peptide groove domain involved in antigen presentation for T cells that will develop and co-stimulate cellular and humoral effector responses. BoLA-DRB3 alleles have been associated with outcomes in infectious diseases such as mastitis, trypanosomiasis, and tick loads, and with production traits. To catalog these alleles, 2 nomenclature methods were proposed, and the current use of both systems makes it difficult to list, comprehend and apply these data effectively. In this review we have organized the knowledge available in all of the reports on the frequencies of BoLA-DRB3 alleles. It covers information from studies made in at least 26 countries on more than 30 breeds; studies are lacking in countries that are important producers of cattle livestock. We highlight practical applications of BoLA studies for identification of markers associated with resistance to infectious and parasitic diseases, increased production traits and T cell epitope mapping, in addition to genetic diversity and conservation studies of commercial and creole and locally adapted breeds. Finally, we provide support for the need of studies to discover new BoLA alleles and uncover unknown roles of this locus in production traits.

Evolutionary pressures rendered by animal husbandry practices for avian influenza viruses to adapt to humans

Commercial poultry operations produce and crowd billions of birds every year, which is a source of inexpensive animal protein. Commercial poultry is intensely bred for desirable production traits, and currently presents very low variability at the major histocompatibility complex. This situation dampens the advantages conferred by the MHC’s high genetic variability, and crowding generates immunosuppressive stress. We address the proteins of influenza A viruses directly and indirectly involved in host specificities. We discuss how mutants with increased virulence and/or altered host specificity may arise if few class I alleles are the sole selective pressure on avian viruses circulating in immunocompromised poultry. This hypothesis is testable with peptidomics of MHC ligands. Breeding strategies for commercial poultry can easily and inexpensively include high variability of MHC as a trait of interest, to help save billions of dollars as a disease burden caused by influenza and decrease the risk of selecting highly virulent strains.

Late-phase dominance of a single epitope-specific CD8+ T-cell response in passive neutralizing antibody-infused simian immunodeficiency virus controllers

OBJECTIVE

Analysis of the quantity and quality of epitope-specific CD8+ T-cell responses is crucial for understanding the mechanism of HIV/simian immunodeficiency virus (SIV) replication control. We have previously shown that acute-phase passive infusion of neutralizing antibodies (NAbs) results in augmented broad T-cell responses and robust SIVmac239 control in rhesus macaques. Analyzing long-term dynamics of CD8+ T-cell responses in these SIV controllers provides important insights into designing lasting anti-HIV immunity.

DESIGN

We analyzed dynamics and metabolic/functional profiles of SIV-specific CD8+ T-cell responses in rhesus macaques that controlled SIVmac239 replication following acute-phase passive NAb infusion.

METHODS

SIV epitope-specific CD8+ T-cell responses in peripheral blood at multiple chronic-phase time points were investigated in four passive NAb-infused SIV controllers. In particular, expression patterns of Eomesodermin (Eomes), phosphorylated AMP kinase (pAMPK), CD28 and programmed death-1 (PD-1) were examined.

RESULTS

In the NAb-infused SIV controllers, a single epitope-specific CD8+ T-cell response detected from acute infection and maintaining low levels up to year 1 showed a surge thereafter, up to year 2 postchallenge. Retention of an effector-skewed and unexhausted Eomes-high/pAMPK-low/CD28-negative/PD-1-low subpopulation in these epitope-specific CD8+ T cells implicated their front-line commitment in residual viral replication control.

CONCLUSION

In long-term SIV control following acute-phase passive NAb infusion, a single-epitope, high-quality CTL response was dominantly induced in the chronic phase. These results likely describe one favorable pattern of immunodominant epitope-specific CD8+ T-cell preservation and suggest the importance of incorporating metabolic marker signatures for understanding NAb/T-cell synergism-based HIV/SIV control.