Pediatric undifferentiated soft tissue sarcomas represent a major challenge for pathologists and clinicians. The goal of this study was to identify cases that warranted this diagnosis by current standards of analysis and then determine if there are clinicopathological commonalities that may be useful for diagnosis, management, and prognosis. Eighteen potential patients were identified using the institutional pathology database. Three cases were reclassified as specific sarcomas, and 2 cases had insufficient material for molecular analysis, leaving 13 cases for pathological review and 12 patients for radiological and clinical review. There were 7 males and 6 females. The median age at diagnosis was 11 years (1 month to 16 years). Tumors commonly involved the trunk (7 of 13; 54%) and ranged in size from 1.7 to 14.5 cm (mean, 6.7 cm). Eleven patients received ifosfamide/etoposide chemotherapy and 4 received irradiation. Five-year event-free and overall survival (EFS and OS) rates were 54% and 74%, respectively. The predominant histological pattern was round to plump spindled cells forming sheets (9 of 13; 69%) and severe atypia was associated with decreased survival (P = 0.048). Immunohistochemistry showed positivity for vimentin (92%), CD117 (92%), and vascular endothelial growth factor (69%), and 8% to 23% showed focal positivity for epithelial, neural, or myogenic markers. Tumors were uniformly negative for translocations associated with pediatric sarcomas. The presence of certain common morphological and immunohistochemical features in the absence of specific molecular genetic abnormalities allows for a diagnosis of pediatric undifferentiated soft tissue sarcoma; however, whether this group of neoplasms forms a unique category of tumors or a common precursor pathway for a number of different sarcomas awaits further study.

Recombinant rabies virus glycoprotein (rRVGP) was expressed in Drosophila melanogaster Schneider 2 (S2) cells. The cDNA encoding the entire RVGP gene was cloned in an expression plasmid under the control of the constitutive actin promoter (Ac), which was co‐transfected into S2 cells together with a hygromycin selection plasmid. Selected S2 cell populations (S2AcRVGP) had a decreased ability to grow and consume substrates, when compared to the non‐transfected cells (S2). They were shown, by PCR, to express the RVGP gene and mRNA and, by immunoblotting, to synthesize the rRVGP in its expected molecular mass of 65 kDa. ELISA kinetic studies showed the rRVGP expression in cell lysates and supernatants attaining concentrations of 300 μg/L. By flow cytometry analysis, about 30% of the cells in the co‐transfected populations were shown to express the rRVGP. Cell populations selected by limiting dilution expressed higher rRVGP yields. Mice immunized with rRVGP were shown to synthesize antibodies against rabies virus and be protected against experimental infection with rabies virus. The data presented here show that S2 cells can be suitable hosts for the rRVGP expression, allowing its synthesis in a high degree of physical and biological integrity.

Hepatitis C virus (HCV) is a major cause of chronic hepatitis worldwide. Studies of the early steps of HCV infection have been hampered by the lack of convenient in vitro or in vivo models. Although several cell-surface molecules that mediate the binding of HCV envelope proteins to target cells have been identified, mechanisms of viral entry into human hepatocytes are still poorly understood. Vesicular stomatitis virus/HCV pseudotyped viruses expressing the HCV envelope glycoproteins on the viral envelope were generated and it was found that their entry into human hepatocytes required co-expression of E1 and E2 on the pseudotype surface. Neutralization of pseudotype infection by anti-HCV antibodies suggested that cellular entry was mediated by HCV envelope glycoproteins and by previously characterized cell-surface molecules, including CD81. An entry assay based on the release of a fluorochrome from labelled HCV pseudotypes provided evidence for a pH-dependent fusion of the pseudotype envelope with a cellular compartment. By using a panel of endocytosis inhibitors, it is postulated that penetration of HCV into primary cultures of hepatocytes takes place by clathrin-mediated endocytosis.

Special thanks are due to Viana do Castelo city for supporting our project. We are also grateful to Agostinho Costinha, the director of Descubra Minho, Lourenço Almada of Associação O Caminho do Garrano. We also thank the villagers in Montaria for their support during our stay, Tetsuro Matsuzawa for the generous guidance throughout the study, and Dora Biro and Valéria Romano for helpful comments on an earlier version of our manuscript. The study was financially supported by grants from the Japan Society for the Promotion of Science (JSPS core-to-core CCSN and JSPS-LGP-U04 to Tetsuro Matsuzawa, KAKENHI Nos. 15H01619 and 15H05309 to Shinya Yamamoto) and the Ministry of Education, Culture, Sports, Science, and Technology in Japan (MEXT No.16H06283 to Tetsuro Matsuzawa). We thank Lilly Gray and Adam Phillips, PhD from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.

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