TMPRSS2 usage by SARS-CoV-2 Omicron impacts tropism and fusogenicity
Here we show that Omicron spike has higher affinity for ACE2 compared to Delta as well as a marked change of antigenicity conferring significant evasion of therapeutic monoclonal and vaccine-elicited polyclonal neutralising antibodies after two doses. mRNA vaccination as a third vaccine dose rescues and broadens neutralization.Importantly, antiviral drugs remdesivir and molnupiravir retain efficacy against Omicron BA.1. Replication was similar for Omicron and Delta virus isolates in human nasal epithelial cultures.
However, in lower airway organoids, lung cells, and gut cells, Omicron demonstrated lower replication. Omicron spike protein was less efficiently cleaved compared to Delta. Replication differences mapped to entry efficiency using spike pseudotyped virus (PV) assays. The defect for Omicron PV to enter specific cell types effectively correlated with higher cellular RNA expression of TMPRSS2, and knock down of TMPRSS2 impacted Delta entry to a greater extent than Omicron.
Furthermore, drug inhibitors targeting specific entry pathways3 demonstrated that the Omicron spike inefficiently utilises the cellular protease TMPRSS2 that promotes cell entry via plasma membrane fusion, with greater dependency on cell entry via the endocytic pathway. Consistent with suboptimal S1/S2 cleavage and inability to utilize joplink CYR61 Antibody TMPRSS2, syncytium formation by the Omicron spike was markedly impaired compared to the Delta spike. Omicron’s less efficient spike cleavage at S1/S2 is associated with shift in cellular tropism away from TMPRSS2 expressing cells, with implications for altered pathogenesis.
A subpopulation of green turtle suprabasal epidermal cells are Langerin+ and migrate under in vitro stimulation of the chemokine CCL21
Dendritic cells form the link between the innate and adaptative immune response, particularly on mucosal and epidermal surfaces. The Langerhans, an epidermal dendritic cell subpopulation, play a key role in the skin immune response across several species. Scarse immune cell subpopulations, including Langerhans-like cells, have been identified in endangered green turtles thereby complicating the understanding of the pathogenesis of diseases such as fibropapillomatosis, which induces skin tumours in this species worldwide.
In biopsies from green turtle skin, we demonstrated that the polyclonal anti-human Langerin antibodies strongly stained a Langerin+ cell population in epidermal sheets, the suprabasal layer of the epidermis in cryosections and in cells from cytospin preparation of migration assays. The morphology of these cells was round to amoeboid in normal skin; however, in skin with ulcerative dermatitis, Langerin+ cells aggregated around ulcers and adopted a more pleomorphic morphology. To our knowledge, this is the first identification of Langerin+ cells with a molecular marker in a reptile species.
Immunohistochemical diagnosis of human infectious diseases: a review
Background: Immunohistochemistry (IHC) using monoclonal and polyclonal antibodies is a useful diagnostic method for detecting pathogen antigens in fixed tissues, complementing the direct diagnosis of infectious diseases by PCR and culture on fresh tissues. It was first implemented in a seminal publication by Albert Coons in 1941.
Main body: Of 14,198 publications retrieved from the PubMed, Google, Google Scholar and Science Direct databases up to December 2021, 230 were selected for a review of IHC techniques, protocols and results. The methodological evolutions of IHC and its application to the diagnosis of infectious diseases, more specifically lice-borne diseases, sexually transmitted diseases and skin infections, were critically examined.
A total of 59 different pathogens have been detected once in 22 different tissues and organs; and yet non-cultured, fastidious and intracellular pathogens accounted for the vast majority of pathogens detected by IHC. Auto-IHC, incorporating patient serum as the primary antibody, applied to diseased heart valves surgically collected from blood culture-negative endocarditis patients, detected unidentified Gram-positive cocci and microorganisms which were subsequently identified as Coxiella burnetii, Bartonella quintana, Bartonella henselae and Tropheryma whipplei. The application of IHC to ancient tissues dated between the ends of the Ptolemaic period to over 70 years ago, have also contributed to paleomicrobiology diagnoses.
Conclusion: IHC plays an important role in diagnostic of infectious diseases in tissue samples. Paleo-auto-IHC derived from auto-IHC, is under development for detecting non-identified pathogens from ancient specimens.
Phosphorylation of hTERT at threonine 249 is a novel tumor biomarker of aggressive cancer with poor prognosis in multiple organs
Recent evidence indicates that RNA-dependent RNA polymerase (RdRP) activity of human telomerase reverse transcriptase (hTERT) regulates expression of target genes and is directly involved in tumor formation by telomere independent manner. Non-canonical function of hTERT has been considered as a therapeutic target for cancer therapy. We have previously shown that hTERT phosphorylation at threonine 249 (p-hTERT), which promotes RdRP activity, is an indicator of an aggressive phenotype and poor prognosis in liver and pancreatic cancers, using two cohorts with small sample sizes with polyclonal p-hTERT antibody.
- To clarify the clinical relevance of p-hTERT, we developed a specific monoclonal antibody and determined the diagnostic and prognostic value of p-hTERT in cancer specimens using a large cohort.
- A monoclonal antibody for phosphorylated hTERT (p-hTERT) at threonine 249 was developed and validated. The antibody was used for the immunohistochemical staining of formalin-fixed paraffin-embedded specimens from 1,523 cases of lung, colon, stomach, pancreatic, liver, breast, and kidney cancers.
- We detected elevated p-hTERT expression levels in cases with a high mitotic activity, high pathological grade, and high nuclear pleomorphism. Elevated p-hTERT expression was an independent prognostic factor for lung, pancreatic, and liver cancers.
- Furthermore, p-hTERT expression was associated with immature and aggressive features, such as adenosquamous carcinoma (lung and pancreas), invasive type of cancer (lung), high serum alfa-fetoprotein level (liver), and triple-negative status (breast).
- In conclusion, RdRP activity indicated by p-hTERT expression predicts aggressive cancer phenotypes in various types of cancer. Thus, p-hTERT is a novel biomarker for the diagnosis of aggressive cancers with a poor prognosis. This article is protected by copyright.
Antibodies directed towards neuraminidase restrict influenza virus replication in primary human bronchial epithelial cells
Influenza neuraminidase (NA) is implicated in various aspects of the virus replication cycle and therefore is an attractive target for vaccination and antiviral strategies. Here we investigated the potential for NA-specific antibodies to interfere with A(H1N1)pdm09 replication in primary human airway epithelial (HAE) cells. Mouse polyclonal anti-NA sera and a monoclonal antibody could block initial viral entry into HAE cells as well as egress from the cell surface.
The NA-specific polyclonal serum also reduced virus replication across multiple rounds of infection. Restriction of virus entry correlated with the ability of the serum or monoclonal antibody to mediate neuraminidase inhibition (NI). Finally, human sera with NI activity against the N1 of A(H1N1)pdm09 could decrease H6N1 virus infection of HAE cells, highlighting the potential contribution of anti-NA antibodies in the control of influenza virus infection in humans.