RESUMO
The COVID-19 pandemic has caused an unprecedented global public health and economy crisis. The origin and emergence of its causal agent, SARS-CoV-2, in the human population remains mysterious, although bat and pangolin were proposed to be the natural reservoirs. Strikingly, comparing to the SARS-CoV-2-like CoVs identified in bats and pangolins, SARS-CoV-2 harbors a polybasic furin cleavage site in its spike (S) glycoprotein. SARS-CoV-2 uses human ACE2 as its receptor to infect cells. Receptor recognition by the S protein is the major determinant of host range, tissue tropism, and pathogenesis of coronaviruses. In an effort to search for the potential intermediate or amplifying animal hosts of SARS-CoV-2, we examined receptor activity of ACE2 from 14 mammal species and found that ACE2 from multiple species can support the infectious entry of lentiviral particles pseudotyped with the wild-type or furin cleavage site deficient S protein of SARS-CoV-2. ACE2 of human/rhesus monkey and rat/mouse exhibited the highest and lowest receptor activity, respectively. Among the remaining species, ACE2 from rabbit and pangolin strongly bound to the S1 subunit of SARS-CoV-2 S protein and efficiently supported the pseudotyped virus infection. These findings have important implications for understanding potential natural reservoirs, zoonotic transmission, human-to-animal transmission, and use of animal models. ImportanceSARS-CoV-2 uses human ACE2 as primary receptor for host cell entry. Viral entry mediated by the interaction of ACE2 with spike protein largely determines host range and is the major constraint to interspecies transmission. We examined the receptor activity of 14 ACE2 orthologues and found that wild type and mutant SARS-CoV-2 lacking the furin cleavage site in S protein could utilize ACE2 from a broad range of animal species to enter host cells. These results have important implications in the natural hosts, interspecies transmission, animal models and molecular basis of receptor binding for SARS-CoV-2.
RESUMO
C3A is a sub-clone of human hepatoblastoma HepG2 cell line with the strong contact inhibition of growth. We fortuitously found that C3A was more susceptible to human coronavirus HCoV-OC43 infection than HepG2, which was attributed to the increased efficiency of virus entry into C3A cells. In an effort to search for the host cellular protein(s) mediating the differential susceptibility of the two cell lines to HCoV-OC43 infection, we found that ADAP2, GILT and LY6E, three cellular proteins with known activity of interfering virus entry, expressed at significantly higher levels in HepG2 cells. Functional analyses revealed that ectopic expression of LY6E, but not GILT or ADAP2, in HEK 293 cells inhibited the entry of HCoV-OC43. While overexpression of LY6E in C3A and A549 cells efficiently inhibited the infection of HCoV-OC43, knockdown of LY6E expression in HepG2 significantly increased its susceptibility to HCoV-OC43 infection. Moreover, we found that LY6E also efficiently restricted the entry mediated by the envelope spike proteins of other human coronaviruses, including the currently pandemic SARS-CoV-2. Interestingly, overexpression of serine protease TMPRSS2 or amphotericin treatment significantly neutralized the IFITM3 restriction of human coronavirus entry, but did not compromise the effect of LY6E on the entry of human coronaviruses. The work reported herein thus demonstrates that LY6E is a critical antiviral immune effector that controls CoV infection and pathogenesis via a distinct mechanism. ImportanceVirus entry into host cells is one of the key determinants of host range and cell tropism and is subjected to the control by host innate and adaptive immune responses. In the last decade, several interferon inducible cellular proteins, including IFITMs, GILT, ADAP2, 25CH and LY6E, had been identified to modulate the infectious entry of a variety of viruses. Particularly, LY6E was recently identified as host factors to facilitate the entry of several human pathogenic viruses, including human immunodeficiency virus, influenza A virus and yellow fever virus. Identification of LY6E as a potent restriction factor of coronaviruses expands the biological function of LY6E and sheds new light on the immunopathogenesis of human coronavirus infection.
RESUMO
<p><b>OBJECTIVE</b>The purpose of our study was to evaluate the predictive factors of the presence of invasive carcinoma associated with intraductal papillary mucinous neoplasm (IPMN) of the pancreas on MDCT and MRI.</p><p><b>METHODS</b>Preoperative MDCT or/and MRI of 27 consecutive patients (19 men, 8 women, mean age 61.3 years) who had undergone surgical resection and had a pathological diagnosis of IPMN were retrospectively assessed. The type of ductal involvement, solid appearance of the lesion, location, tumor size of branch duct type and combined type lesions, maximum diameter of the tumor, caliber of the main pancreatic duct and the extent of the common bile duct dilatation were assessed on CT and MRI and correlated with the pathological findings of the invasive carcinoma. Two abdominal radiologists reviewed all the images, and when discrepancies of the findings were found, the consensus was reached by discussion.</p><p><b>RESULTS</b>Pathological analysis revealed carcinoma in situ in two patients and invasive carcinoma in 19 patients arising from the IPMN. The type of ductal involvement (P = 0.038), a solid mass (P = 0.003) and the common bile duct dilatation ( ≥ 15 mm, P = 0.004) were correlated with the presence of associated invasive carcinoma. For the finding of solid and cystic mass in predicting invasive IPMN, the sensitivity was 66.7% (8/12) and specificity was 100.0% (8/8), and for bile duct diameter ≥ 15 mm, the sensitivity was 47.4% (9/19) and specificity was 100.0% (8/8). However, no association was found between the location of the lesion and associated invasive carcinoma. The caliber of the main pancreatic duct of patients with associated invasive carcinoma was significantly larger than that in the cases without invasive carcinoma (8.07 ± 2.23 mm vs. 4.86 ± 1.86 mm, P = 0.002). When using the main pancreatic duct dilatation ≥ 4 mm as the threshold, the sensitivity and specificity in predicting invasive IPMN were 94.7% (18/19) and 37.5% (3/8), respectively. For the branch duct type and combined type, the size of the tumor with associated invasive carcinoma was significantly larger than these without invasive carcinoma (41.35 ± 12.58) mm vs. (23.76 ± 8.06) mm (P = 0.003). When the maximum diameter was ≥ 40 mm, the sensitivity and specificity in predicting invasive IPMN were 50.0% (6/12) and 87.5% (7/8), respectively.</p><p><b>CONCLUSIONS</b>The findings of CT and MRI are helpful to predict invasive carcinoma associated with IPMN, which may play an important role in the preoperative evaluation, surgical planning and predicting the prognosis of IPMN.</p>
