The ability of a 3-gene host signature in blood to distinguish tuberculous meningitis from other brain infections.

BACKGROUND: Tuberculous meningitis (TBM) is difficult to diagnose. We investigated whether a 3-gene host response signature in blood can distinguish TBM from other brain infections. METHODS: The expression of 3 genes (Dual specificity phosphatase 3- DUSP3, Guanylate-binding protein- GBP5, Krupple-like factor 2- KLF2) was analysed by RNA sequencing of archived whole blood from four cohorts of Vietnamese adults: 281 with TBM; 279 with pulmonary tuberculosis; 50 with other brain infections; and 30 healthy controls. 'TB scores' (combined 3-gene expression) were calculated following published methodology and discriminatory performance compared using area under a receiver operator characteristic curve (AUC). RESULTS: GBP5 was upregulated in TBM compared to other brain infections (p < 0.001), with no difference in DUSP3 and KLF2 expression. The diagnostic performance of GBP5 alone (AUC 0.74 (95% CI 0.67-0.81)) was slightly better than the 3-gene TB score (AUC 0.66, 95% CI 0.58-0.73) in TBM. Both GBP5 expression and TB score were higher in HIV-positive participants (P < 0.001), with good diagnostic performance of GBP5 alone (AUC 0.86, 95% CI 0.80-0.93). CONCLUSION: The 3-gene host signature in whole blood has the ability to discriminate TBM from other brain infections, including in HIV-positive individuals. Validation in large prospective diagnostic study is now required.

Drosophila Claspin is required for the G2 arrest that is induced by DNA replication stress but not by DNA double-strand breaks.

ATR and Chk1 are protein kinases that perform major roles in the DNA replication checkpoint that delays entry into mitosis in response to DNA replication stress by hydroxyurea (HU) treatment. They are also activated by ionizing radiation (IR) that induces DNA double-strand breaks. Studies in human tissue culture and Xenopus egg extracts identified Claspin as a mediator that increased the activity of ATR toward Chk1. Because the in vivo functions of Claspin are not known, we generated Drosophila lines that each contained a mutated Claspin gene. Similar to the Drosophila mei-41/ATR and grp/Chk1 mutants, embryos of the Claspin mutant showed defects in checkpoint activation, which normally occurs in early embryogenesis in response to incomplete DNA replication. Additionally, Claspin mutant larvae were defective in G2 arrest after HU treatment; however, the defects were less severe than those of the mei-41/ATR and grp/Chk1 mutants. In contrast, IR-induced G2 arrest, which was severely defective in mei-41/ATR and grp/Chk1 mutants, occurred normally in the Claspin mutant. We also found that Claspin was phosphorylated in response to HU and IR treatment and a hyperphosphorylated form of Claspin was generated only after HU treatment in mei-41/ATR-dependent and tefu/ATM-independent way. In summary, our data suggest that Drosophila Claspin is required for the G2 arrest that is induced by DNA replication stress but not by DNA double-strand breaks, and this difference is probably due to distinct phosphorylation statuses.