Ribonucleotide reductases (RRs) are evolutionarily-conserved enzymes that catalyze the rate-limiting step during dNTP synthesis in mammals. RR consists of both large (R1) and small (R2) subunits, which are both required for catalysis by the R12R22 heterotetrameric complex. Poxviruses also encode RR proteins, but while the Orthopoxviruses infecting humans [e.g. vaccinia (VACV), variola, cowpox, and monkeypox viruses] encode both R1 and R2 subunits, the vast majority of Chordopoxviruses encode only R2 subunits. Using plaque morphology, growth curve, and mouse model studies, we investigated the requirement of VACV R1 (I4) and R2 (F4) subunits for replication and pathogenesis using a panel of mutant viruses in which one or more viral RR genes had been inactivated. Surprisingly, VACV F4, but not I4, was required for efficient replication in culture and virulence in mice. The growth defects of VACV strains lacking F4 could be complemented by genes encoding other Chordopoxvirus R2 subunits, suggesting conservation of function between poxvirus R2 proteins. Expression of F4 proteins encoding a point mutation predicted to inactivate RR activity but still allow for interaction with R1 subunits, caused a dominant negative phenotype in growth experiments in the presence or absence of I4. Co-immunoprecipitation studies showed that F4 (as well as other Chordopoxvirus R2 subunits) form hybrid complexes with cellular R1 subunits. Mutant F4 proteins that are unable to interact with host R1 subunits failed to rescue the replication defect of strains lacking F4, suggesting that F4-host R1 complex formation is critical for VACV replication. Our results suggest that poxvirus R2 subunits form functional complexes with host R1 subunits to provide sufficient dNTPs for viral replication. Our results also suggest that R2-deficient poxviruses may be selective oncolytic agents and our bioinformatic analyses provide insights into how poxvirus nucleotide metabolism proteins may have influenced the base composition of these pathogens.

Background: Small intestine adenocarcinoma is a rare cancer. The current study aims to determine the outcomes of patients with small intestine adenocarcinoma in a Canadian province. Methods: This retrospective population-based cohort study assessed patients with small intestine adenocarcinoma who were diagnosed from 2008 to 2017 in Saskatchewan. A Cox proportional multivariate regression analysis was performed to determine the correlation between survival and exploratory factors. Results: 112 eligible patients with a median age of 73 years and M:F of 47:53 were identified. Overall, 75% had a comorbid illness, and 45% had a WHO performance status >1. Of the 112 patients, 51 (46%) had early-stage disease and 61 (54%) had advanced-stage disease. The median overall survival (mOS) was as follows: stage one, 59 months; stage two, 30 months; stage three, 20 months; and stage four, 3 months (p < 0.001). The median disease-free survival of patients with stage three disease who received adjuvant chemotherapy was 26 months (95% CI:23.1–28.9) vs. 4 months (0.0–9.1) with observation (p = 0.04). Patients who received chemotherapy for advanced disease had a mOS of 10 months (3.5–16.5) vs. 2 months (0.45–3.6) without chemotherapy (p < 0.001). In the multivariate analysis, stage four disease, hazard ratio (HR), 3.20 (1.84–5.40); WHO performance status >1, HR, 2.22 (1.42–3.45); lack of surgery, HR, 2.10 (1.25–3.50); and a neutrophil:lymphocyte ratio of >4.5, HR, 1.72 (1.10–2.71) were significantly correlated with inferior survival. Conclusions: Most patients with small intestine adenocarcinoma were diagnosed with advanced-stage disease. Advanced-stage disease, poor performance status, lack of surgery and a baseline neutrophil:lymphocyte ratio >4.5 were correlated with inferior survival.

Abstract:The H1N1 viral envelope protein neuraminidase encoded by NA gene plays a key role in the pathogenesis of swine flu. The active site of the neuraminidase protein is targeted by presently available antiviral drugs. The influenza virus often proves to be resistant to currently available drugs, due single amino acid substitutions conferred by the mutations in the gene coding for neuraminidase protein. The latest Influenza A virus A/Perth/262/2009(H1N1) sequence with accession number ADJ67981 was selected from NCBI. The BLAST program was used to identify the best template structure, which was found to be 3NSS_A. Sequence alignment was carried out with the template and query sequence, the identity and similarity was found to be 81.9% and 82.6% respectively. Homology modeling was performed using Accelrys Discovery Studio 3.5 software, the model with the lowest energy was then assessed for stereochemical quality and side-chain environment. The PDF energy and DOPE score of the best modeled structure was 2090.1682 and -43752.3632 respectively. Further active site optimization of the modeled protein was performed by molecular dynamics. The key active site residues which are crucial for further docking studies were ascertained.

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