Rabbit Anti-Human BST2 Polyclonal antibody

Viruses must negotiate cellular antiviral responses in order to replicate. Human cytomegalovirus (HCMV) is a prevalent betaherpesvirus that encodes a number of viral gene products that modulate cellular antiviral signaling. The HCMV U(L)26 gene has previously been found to attenuate cytokine-activated NF-kappa B signaling, yet the role that U(L)26 plays in modulating the host cell's global transcriptional response to infection is not clear. Here, we find that infection with a U(L)26 deletion virus (Delta U(L)26) induces a proinflammatory transcriptional environment that includes substantial increases in the expression of cytokine signaling genes relative to wild-type HCMV. These increases include NF-kappa B-regulated genes as well as interferon-stimulated genes (ISGs), such as ISG15 and bone marrow stromal cell antigen 2 (BST2). The Delta U(L)26 mutant-mediated induction of ISG15 expression was found to drive increases in global protein ISGylation during Delta U(L)26 mutant infection. However, short hairpin RNA (shRNA) and CRISPR-mediated targeting of ISG15 indicated that its induction does not restrict HCMV infection. In contrast, shRNA-mediated targeting of BST2 demonstrated that BST2 restricts HCMV cell-to-cell spread. In addition, the increased expression of both of these ISGs and the global enhancement in protein ISGylation were found to be dependent on the activity of the canonical inhibitor of NF-kappa B kinase beta (IKK beta). Both CRISPR-based and pharmacologically mediated inhibition of IKK beta blocked the induction of ISG15 and BST2. These results suggest significant cross-talk between the NF-kappa B and interferon signaling pathways and highlight the importance of IKK signaling and the HCMV U(L)26 protein in shaping the antiviral response to HCMV. IMPORTANCE Modulation of cellular antiviral signaling is a key determinant of viral pathogenesis. Human cytomegalovirus (HCMV) is a significant source of morbidity in neonates and the immunosuppressed that contains many genes that modulate antiviral signaling, yet how these genes contribute to shaping the host cell's transcriptional response to infection is largely unclear. Our results indicate that the HCMV U(L)26 protein is critical in preventing the establishment of a broad cellular proinflammatory transcriptional environment. Further, we find that the host gene IKK beta is an essential determinant governing the host cell's antiviral transcriptional response. Given their importance to viral pathogenesis, continuing to elucidate the functional interactions between viruses and the cellular innate immune response could enable the development of therapeutic strategies to limit viral infection.

The current availability of five complete genomes of different primate species allows the analysis of genetic divergence over the last 40 million years of evolution. We hypothesized that the interspecies differences observed in susceptibility to HIV-1 would be influenced by the long-range selective pressures on host genes associated with HIV-1 pathogenesis. We established a list of human genes (n = 140) proposed to be involved in HIV-1 biology and pathogenesis and a control set of 100 random genes. We retrieved the orthologous genes from the genome of humans and of four nonhuman primates (Pan troglodytes, Pongo pygmaeus abeli, Macaca mulatta, and Callithrix jacchus) and analyzed the nucleotide substitution patterns of this data set using codon-based maximum likelihood procedures. In addition, we evaluated whether the candidate genes have been targets of recent positive selection in humans by analyzing HapMap Phase 2 single-nucleotide polymorphisms genotyped in a region centered on each candidate gene. A total of 1,064 sequences were used for the analyses. Similar median K-A/K-S values were estimated for the set of genes involved in HIV-1 pathogenesis and for control genes, 0.19 and 0.15, respectively. However, genes of the innate immunity had median values of 0.37 (P value = 0.0001, compared with control genes), and genes of intrinsic cellular defense had K-A/K-S values around or greater than 1.0 (P value = 0.0002). Detailed assessment allowed the identification of residues under positive selection in 13 proteins: AKT1, APOBEC3G, APOBEC3H, CD4, DEFB1, GML, IL4, IL8RA, L-SIGN/CLEC4M, PTPRC/CD45, Tetherin/BST2, TLR7, and TRIM5 alpha. A number of those residues are relevant for HIV-1 biology. The set of 140 genes involved in HIV-1 pathogenesis did not show a significant enrichment in signals of recent positive selection in humans (intraspecies selection). However, we identified within or near these genes 24 polymorphisms showing strong signatures of recent positive selection. Interestingly, the DEFB1 gene presented signatures of both interspecies positive selection in primates and intraspecies recent positive selection in humans. The systematic assessment of long-acting selective pressures on primate genomes is a useful tool to extend our understanding of genetic variation influencing contemporary susceptibility to HIV-1.