A natural variation in the RNA polymerase of severe fever with thrombocytopenia syndrome virus enhances viral replication and in vivo virulence

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease with high mortality in Eastern Asia. The disease is caused by the SFTS virus (SFTSV), also known as Dabie bandavirus, which has a segmented RNA genome consisting of L, M, and S segments. Previous studies have suggested differential viral virulence depending on the genotypes of SFTSV; however, the critical viral factor involved in the differential viral virulence is unknown. Here, we found a significant difference in viral replication in vitro and virulence in vivo between two Korean isolates belonging to the F and B genotypes, respectively. By generating viral reassortants using the two viral strains, we demonstrated that the L segment, which encodes viral RNA-dependent RNA polymerase (RdRp), is responsible for the enhanced viral replication and virulence. Comparison of amino acid sequences and viral replication rates revealed a point variation, E251K, on the surface of RdRp to be the most significant determinant for the enhanced viral replication rate and in vivo virulence. The effect of the variation was further confirmed using recombinant SFTSV generated by reverse genetic engineering. Therefore, our results indicate that natural variations affecting the viral replicase activity could significantly contribute to the viral virulence of SFTSV.

Virus blocking textile for SARS-CoV-2 using human body triboelectric energy harvesting

Effective mitigation technology to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is required before achieving population immunity through vaccines. Here we demonstrate a virus-blocking textile (VBT) that repulses SARS-CoV-2 by applying repulsive Coulomb force to respiratory particles, powered by human body triboelectric energy harvesting. We show that SARS-CoV-2 has negative charges, and a human body generates high output current of which peak-to-peak value reaches 259.6 μA at most, based on triboelectric effect. Thereby, the human body can sustainably power a VBT to have negative electrical potential, and the VBT highly blocks SARS-CoV-2 by repulsion. In an acrylic chamber study, we found that the VBT blocks SARS-CoV-2 by 99.95%, and SARS-CoV-2 in the VBT is 13-fold reduced. Our work provides technology that may prevent the spread of virus based on repulsive Coulomb force and triboelectric energy harvesting.

Enhanced eosinophil-mediated inflammation associated with antibody and complement-dependent pneumonic insults in critical COVID-19

Despite the worldwide effect of the coronavirus disease 2019 (COVID-19) pandemic, the underlying mechanisms of fatal viral pneumonia remain elusive. Here, we show that critical COVID-19 is associated with enhanced eosinophil-mediated inflammation when compared to non-critical cases. In addition, we confirm increased T helper (Th)2-biased adaptive immune responses, accompanying overt complement activation, in the critical group. Moreover, enhanced antibody responses and complement activation are associated with disease pathogenesis as evidenced by formation of immune complexes and membrane attack complexes in airways and vasculature of lung biopsies from six fatal cases, as well as by enhanced hallmark gene set signatures of Fcγ receptor (FcγR) signaling and complement activation in myeloid cells of respiratory specimens from critical COVID-19 patients. These results suggest that SARS-CoV-2 infection may drive specific innate immune responses, including eosinophil-mediated inflammation, and subsequent pulmonary pathogenesis via enhanced Th2-biased immune responses, which might be crucial drivers of critical disease in COVID-19 patients.

Severe Fever with Thrombocytopenia Syndrome Virus Infection or Mixed Infection with Scrub Typhus in South Korea in 2000-2003

Severe fever with thrombocytopenia syndrome is a tick-borne viral disease, with a high mortality rate that was first reported in China in 2009. Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi, a bacterium transmitted to humans through chigger mite bites. Severe fever with thrombocytopenia syndrome and scrub typhus are endemic to South Korea. To investigate evidence of severe fever with thrombocytopenia syndrome virus (SFTSV) infection or mixed infection with scrub typhus in South Korea, we examined 2,329 sera samples collected from patients presenting from November 1, 2000, to November 1, 2003, for the diagnosis of rickettisal diseases at Seoul National University, Seoul, South Korea. We found retrospective evidence of SFTSV infection or mixed infection with scrub typhus in South Korea in 2000-2003. Severe fever with thrombocytopenia syndrome virus infections in South Korea occurred before previously reported cases and were more concurrent with those in China. It is important to consider SFTSV infection in patients with scrub typhus.

A case of combined gastrojejunal and gastrocolic fistula secondary to gastric cancer

A rare case of gastric cancer associated with gastrojejunal and gastrocolic fistula is presented. A 56-year-old man who had been diagnosed with advanced gastric cancer(Borrmann's type III) 5 months previously was admitted due to watery diarrhea and frequent vomiting for 2 weeks. Fluoroscopic examination was visualized two abnormal passage of contrast medium from the stomach, one to the colon, and the other to the jejunum. Gastrofiberscopy revealed that the tumor on the great curvature of the body appeared to penetrate into the colon, while the other one on the antrum directly invaded into the jejunum. The patient was treated conservatively with total parenteral nutrition and pain control.

MR imaging of tubo-ovarian abscess

PURPOSE AND MATERIAL AND METHODS: MR findings of 9 surgically proven tubo-ovarian abscesses were analyzed in 8 patients. The images were evaluated for signal intensity characteristics and morphologic appearance of the mass, and presence of secondary changes in adjacent pelvic organs and structures.

RESULTS

The signal intensity of the lesions on T1-weighted images was hypointense to the surrounding muscle and myometrium in 5 patients, isointense in 3 and hyperintense in 1. On T2-weighted images the signal intensity was hyperintense (n = 6) or heterogeneous (n = 3). A thin rim (1-3 mm) with hyperintensity on T1-weighted images was noted in the innermost aspect of the masses. Other findings were ill-defined margin, thickened wall, multiple internal septa, shading and gas collection. "Mesh-like" linear strands were noted in the pelvis in all patients, with involvement of adjacent pelvic organs in 7 and lymphadenopathy in 3.

CONCLUSIONS

In this limited number of cases MR imaging showed great potential for demonstrating the extent of the disease, characterizing the lesions and making a specific diagnosis.

Abdominal actinomycosis: CT findings in 10 patients

OBJECTIVE

The purpose of this study was to analyze the CT findings in 10 patients with abdominal actinomycosis to determine the appearance of lesions and the pattern of spread of the disease.

MATERIALS AND METHODS

We retrospectively reviewed the CT findings in 10 patients with pathologically proved actinomycosis. Involved areas were the pelvis (n = 4), greater omentum (n = 3), liver (n = 2), and kidney (n = 1). Contrast-enhanced (oral and IV) CT scans were available in all patients. Unenhanced CT scans were also available in six patients.

RESULTS

CT scans showed mostly solid masses with focal areas of diminished attenuation in seven patients and mostly cystic masses with thickened walls in three. CT findings confirmed the infiltrative nature of the disease, showing its tendency to invade across tissue planes and boundaries. Dense inhomogeneous contrast enhancement in the walls or solid components of masses was seen in eight patients. Minimal lymphadenopathy was seen in only two patients.

CONCLUSION

Although nonspecific, actinomycosis should be included in the differential diagnosis when CT scans show an infiltrative mass with unusual aggressiveness and dense inhomogeneous contrast enhancement, especially in patients with fever, leukocytosis, or long-term use of intrauterine contraceptive devices.