A macaque clonal hematopoiesis model demonstrates expansion of TET2-disrupted clones and utility for testing interventions

Individuals with age-related clonal hematopoiesis (CH) are at greater risk for hematologic malignancies and cardiovascular diseases. However, predictive preclinical animal models to recapitulate the spectrum of human CH are lacking. Through error-corrected sequencing of 56 human CH/myeloid malignancy genes, we identified natural CH driver mutations in aged rhesus macaques matching genes somatically mutated in human CH, with DNMT3A mutations being the most frequent. A CH model in young adult macaques was generated via autologous transplantation of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9-mediated gene-edited hematopoietic stem and progenitor cells (HSPCs), targeting the top human CH genes with loss-of-function (LOF) mutations. Long-term follow-up revealed reproducible and significant expansion of multiple HSPC clones with heterozygous TET2 LOF mutations, compared with minimal expansion of clones bearing other mutations. Although the blood counts of these CH macaques were normal, their bone marrows were hypercellular and myeloid-predominant. TET2-disrupted myeloid colony-forming units isolated from these animals showed a distinct hyperinflammatory gene expression profile compared with wild type. In addition, mature macrophages purified from the CH macaques showed elevated NLRP3 inflammasome activity and increased interleukin-1 beta (IL-1 beta) and IL-6 production. The model was used to test the impact of IL-6 blockage by tocilizumab, documenting a slowing of TET2-mutated expansion, suggesting that interruption of the IL-6 axis may remove the selective advantage of mutant HSPCs. These findings provide a model for examining the pathophysiology of CH and give insights into potential therapeutic interventions.N

Uniformity of rotavirus strain nomenclature proposed by the Rotavirus Classification Working Group (RCWG)

In April 2008, a nucleotide sequence-based, complete genome classification system was developed for group A rotaviruses (RVs). This system assigns a specific genotype to each of the 11 genome segments of a particular RV strain according to established nucleotide percent cut-off values. Using this approach, the genome of individual RV strains are given the complete descriptor of Gx-P[x]-Ix-Rx-Cx-Mx-Ax-Nx-Tx-Ex-Hx. A Rotavirus Classification Working Group (RCWG) was formed by scientists in the field to maintain, evaluate, and develop the RV genotype classification system, in particular to aid in the designation of new genotypes. Since its conception, the group has ratified 50 new genotypes: as of January 2011, new genotypes for VP7 (G20–G26), VP4 (P[28]–P[35]), VP6 (I12–I16), VP1 (R5–R9), VP2 (C6–C9), VP3 (M7–M8), NSP1 (A15–A16), NSP2 (N6–N9), NSP3 (T8–T12), NSP4 (E12–E14), and NSP5/6 (H7–H11) have been defined for RV strains identified in humans, cows, pigs, horses, mice, South American camelids (guanaco and vicuña), chickens, turkeys, pheasants, and bats. With increasing numbers of complete RV genome sequences becoming available, a standardized RV strain nomenclature system is needed and the RCWG proposes that individual RV strains are named as follows: RV group/species of origin/country of identification/common name/year of identification/G- and P-type. In collaboration with the National Center for Biotechnology Information (NCBI), the RCWG is also working on developing a RV-specific resource for the deposition of nucleotide sequences. This resource will provide useful information regarding RV strains, including but not limited to, the individual gene genotypes, epidemiological, and clinical information. Together, the proposed nomenclature system and the NCBI RV resource will offer highly useful tools for investigators to search for, retrieve, and analyze the ever-growing volume of RV genomic data