Mutations in modified virus Ankara protein 183 render it a non-functional counterpart of B14, an inhibitor of nuclear factor κB activation

Vaccinia virus (VACV) encodes multiple proteins to evade host innate immunity, including B14, a virulence factor that binds to the inhibitor of κB kinase β (IKKβ) and blocks nuclear factor κB (NF-κB) activation. B14 shares 95 % amino acid identity with the 183 protein encoded by modified virus Ankara (MVA), an attenuated VACV strain being developed as a vaccine vector. To evaluate whether the immunogenicity of MVA might be increased by manipulation of MVA immunomodulatory proteins, the MVA counterpart of B14, protein 183, was characterized. Unlike B14, protein 183 was unstable in eukaryotic cells unless proteasome-mediated protein degradation was inhibited. Furthermore, 183 did not inhibit NF-κB activation in response to cytokine stimulation, and did not restore the virulence of VACV strain Western Reserve lacking gene B14R. The instability and non-functionality of 183 are probably explained by a deletion of 6 aa within α-helix 6 of the B14 crystal structure

A mechanism for the inhibition of DNA-PK-mediated DNA sensing by a virus

The innate immune system is critical in the response to infection by pathogens and it is activated by pattern recognition receptors (PRRs) binding to pathogen associated molecular patterns (PAMPs). During viral infection, the direct recognition of the viral nucleic acids, such as the genomes of DNA viruses, is very important for activation of innate immunity. Recently, DNA-dependent protein kinase (DNA-PK), a heterotrimeric complex consisting of the Ku70/Ku80 heterodimer and the catalytic subunit DNA-PKcs was identified as a cytoplasmic PRR for DNA that is important for the innate immune response to intracellular DNA and DNA virus infection. Here we show that vaccinia virus (VACV) has evolved to inhibit this function of DNA-PK by expression of a highly conserved protein called C16, which was known to contribute to virulence but by an unknown mechanism. Data presented show that C16 binds directly to the Ku heterodimer and thereby inhibits the innate immune response to DNA in fibroblasts, characterised by the decreased production of cytokines and chemokines. Mechanistically, C16 acts by blocking DNA-PK binding to DNA, which correlates with reduced DNA-PK-dependent DNA sensing. The C-terminal region of C16 is sufficient for binding Ku and this activity is conserved in the variola virus (VARV) orthologue of C16. In contrast, deletion of 5 amino acids in this domain is enough to knockout this function from the attenuated vaccine strain modified vaccinia virus Ankara (MVA). In vivo a VACV mutant lacking C16 induced higher levels of cytokines and chemokines early after infection compared to control viruses, confirming the role of this virulence factor in attenuating the innate immune response. Overall this study describes the inhibition of DNA-PK-dependent DNA sensing by a poxvirus protein, adding to the evidence that DNA-PK is a critical component of innate immunity to DNA viruses

Vaccinia virus protein C16 acts intracellularly to modulate the host response and promote virulence

The vaccinia virus (VACV) strain Western Reserve C16 protein has been characterized and its effects on virus replication and virulence have been determined. The C16L gene is present in the inverted terminal repeat and so is one of the few VACV genes that are diploid. The C16 protein is highly conserved between different VACV strains, and also in the orthopoxviruses variola virus, ectromelia virus, horsepox virus and cowpox virus. C16 is a 37.5 kDa protein, which is expressed early during infection and localizes to the cell nucleus and cytoplasm of infected and transfected cells. The loss of the C16L gene had no effect on virus growth kinetics but did reduce plaque size slightly. Furthermore, the virulence of a virus lacking C16L (vΔC16) was reduced in a murine intranasal model compared with control viruses and there were reduced virus titres from 4 days post-infection. In the absence of C16, the recruitment of inflammatory cells in the lung and bronchoalveolar lavage was increased early after infection (day 3) and more CD4+ and CD8+ T cells expressed the CD69 activation marker. Conversely, late after infection with vΔC16 (day 10) there were fewer T cells remaining, indicating more rapid clearance of infection. Collectively, these data indicate that C16 diminishes the immune response and is an intracellular immunomodulator

Laparoscopic resection of intra-abdominal metastasis from intracranial hemangiopericytoma

Introduction: Hemangiopericytoma (HPC) is a rare mesenchymal tumor derived from capillary and postcapillary pericytes that often has an indolent course and occasionally presents with abdominal metastasis. Presentation of case: Twenty-three years after the initial resection of an intracranial HPC located in the right frontoparietal region and left lateral ventricle, a 63-year-old man experienced dull abdominal pain and early satiety and had a palpable epigastric mass. Computed tomography indicated a suspected metastasis of HPC to the left upper abdomen. On laparoscopic exploration, the tumor was found in the falciform ligament and was excised laparoscopically per request of the patient. He had a fast recovery and experienced good relief of his pain and satiety. The patient had 2 additional metastases at his 12-month follow-up, both in the right retroperitoneum, and he again underwent laparoscopic resection. At his next annual follow-up, new metastases were identified in his liver, small-bowel mesentery, and peritoneal surface, prompting a trial of systemic chemotherapy. Because of progress of a left lower abdominal preperitoneal metastasis on follow-up at 3 years, the patient underwent a further successful laparoscopic exploration. Postoperatively, systemic chemotherapy was maintained. Discussion: We report the recurrent laparoscopic resection of peritoneal metastases of primary intracranial HPC with good symptom control and fast recovery. Both the patient and the referring physician requested a minimally invasive surgical approach. Conclusion: Laparoscopic resection is a feasible treatment strategy for intraperitoneal metastases and is effective in symptom palliation

Omphalocele with intestinal prolapse through a patent omphalomesenteric duct: A case report

Introduction: The combination of a patent omphalomesenteric duct in the setting of an omphalocele is rare and has an unusual physical appearance on presentation. Case presentation: We share the case of a neonate who presented with omphalocele and a concurrent patent omphalomesenteric duct with intestinal prolapse. We report the early diagnosis and operative management of this presentation with intestinal resection and anastomosis, and primary closure of the omphalocele. The patient had no other abnormalities and after uncomplicated recovery, was able to discharge uneventfully tolerating oral feeds. Conclusion: Because the initial appearance of a patent omphalomesenteric duct in an omphalocele is unusual with visible bowel mucosa and an intact omphalocele membrane, this variation of an abdominal wall defect is at risk of being misdiagnosed as a ruptured omphalocele, gastroschisis, or another complex abdominal wall defect. Expeditious surgical management is indicated

Surgical management of acutely ruptured hepatoblastoma with definitive oncologic resection

Hepatoblastoma is the most common liver tumor in childhood. In a minority of cases, hepatoblastomas can present with tumor rupture and hemorrhage, particularly in the setting of rapid tumor growth or rapid necrosis after the initiation of chemotherapy. While surgical resection is the mainstay of definitive care in treatment of nonruptured lesions, rupture presents unique challenges in terms of emergent interventions as well as definitive oncologic care. Management of a patient with a symptomatic ruptured hepatoblastoma involves either i) emergent control of hemorrhage with embolization (or operative control of bleeding) followed by adjuvant chemotherapy and definitive resection at a later date, or ii) emergent oncologic resection at presentation followed by adjuvant chemotherapy. We report the case of a 19 month old child with recently diagnosed hepatoblastoma who presented with tumor rupture and hemorrhage shortly after the initiation of chemotherapy. She underwent emergency definitive oncologic resection and recovered well to resume and complete chemotherapy

A mechanism for the inhibition of DNA-PK-mediated DNA sensing by a virus.

The innate immune system is critical in the response to infection by pathogens and it is activated by pattern recognition receptors (PRRs) binding to pathogen associated molecular patterns (PAMPs). During viral infection, the direct recognition of the viral nucleic acids, such as the genomes of DNA viruses, is very important for activation of innate immunity. Recently, DNA-dependent protein kinase (DNA-PK), a heterotrimeric complex consisting of the Ku70/Ku80 heterodimer and the catalytic subunit DNA-PKcs was identified as a cytoplasmic PRR for DNA that is important for the innate immune response to intracellular DNA and DNA virus infection. Here we show that vaccinia virus (VACV) has evolved to inhibit this function of DNA-PK by expression of a highly conserved protein called C16, which was known to contribute to virulence but by an unknown mechanism. Data presented show that C16 binds directly to the Ku heterodimer and thereby inhibits the innate immune response to DNA in fibroblasts, characterised by the decreased production of cytokines and chemokines. Mechanistically, C16 acts by blocking DNA-PK binding to DNA, which correlates with reduced DNA-PK-dependent DNA sensing. The C-terminal region of C16 is sufficient for binding Ku and this activity is conserved in the variola virus (VARV) orthologue of C16. In contrast, deletion of 5 amino acids in this domain is enough to knockout this function from the attenuated vaccine strain modified vaccinia virus Ankara (MVA). In vivo a VACV mutant lacking C16 induced higher levels of cytokines and chemokines early after infection compared to control viruses, confirming the role of this virulence factor in attenuating the innate immune response. Overall this study describes the inhibition of DNA-PK-dependent DNA sensing by a poxvirus protein, adding to the evidence that DNA-PK is a critical component of innate immunity to DNA viruses