Replication of Epstein-Barr virus primary infection in human tonsil tissue explants

Modulation of cytokeratin and cytokine/chemokine expression following influenza virus infection of differentiated human tonsillar epithelial cells

The tonsils have been identified as a site of replication for Epstein-Barr virus, adenovirus, human papillomavirus, and other respiratory viruses. Human tonsil epithelial cells (HTECs) are a heterogeneous group of actively differentiating cells. Here, we investigated the cellular features and susceptibility of differentiated HTECs to specific influenza viruses, including expression of avian-type and mammalian-type sialic acid (SA) receptors, viral replication dynamics, and the associated cytokine secretion profiles. We found that differentiated HTECs possess more abundant α2,3-linked SA (preferentially bound by avian influenza viruses) than α2,6-linked SA (preferentially bound by mammalian strains). This dual receptor expression suggests a role in influenza virus adaptation and tropism within the tonsils by facilitating the binding and entry of multiple influenza virus strains. Our results indicated the susceptibility of differentiated HTECs to a wide range of influenza viruses from human, swine, and avian hosts. Virus production for most strains was detected as early as 1 day post-infection (dpi), and typically peaked by 3 dpi. However, pandemic H1N1 virus showed remarkably delayed replication kinetics that did not peak until at least 7 dpi. Notably, influenza virus infection impacted the expression of cytokeratins in HTEC cultures, which correlated with altered cytokine secretion patterns. These patterns varied within the strains but were most distinct in swine H3N2 infection. In conclusion, differentiated HTECs exhibited a strain-specific pattern of influenza virus replication and innate immune responses that included changes in cytokeratin and cytokine expression. These studies shed light on the complex interplay between influenza viruses and host cells in the tonsils.

IMPORTANCE

To develop effective interventions against influenza, it is important to identify host factors affecting pathogenesis and immune responses. Tonsils are lymphoepithelial organs characterized by infiltration of B and T lymphocytes into the squamous epithelium of tonsillar crypts, beneath which germinal centers play key roles in antigen processing and the immune response. Influenza virus tropism in the human upper respiratory tract is a key determinant of host-range, pathogenesis, and transmission. Accordingly, experimental models using primary cells from the human respiratory tract are relevant for assessing virus tropism and replication competence. Our study addresses the dynamics of influenza virus replication in HTECs, including cellular tropism, infectivity, and cytokeratin and cytokine expression. The results of this study highlight the complex interplay between structural proteins and immune signaling pathways, all of which provide valuable insights into host-virus interactions.

Mapping and modelling human B cell maturation in the germinal centre

The maturation of B cells within the germinal centre (GC) is necessary for antigen-specific immune responses and memory. Dysfunction in the GC can lead to immunodeficiencies, autoimmune diseases, or lymphomas. Here we describe how recent advances in single-cell and spatial genomics have enabled new discoveries about the diversity of human GC B cell states. However, with the advent of these hypothesis-generating technologies, the field should now transition towards testing bioinformatic predictions using experimental models of the human GC. We review available experimental culture systems for modelling human B cell responses and discuss the potential limitations of different methods in capturing bona fide GC B cell states. Together, the combination of cell atlas-based mapping with experimental modelling of lymphoid tissues holds great promise to better understand the maturation of human B cells in the GC response and generate new insights into human immune health and disease.

Modelling human papillomavirus biology in oropharyngeal keratinocytes

Most human papillomavirus (HPV) positive head and neck cancers arise in the tonsil crypts; deep invaginations at the tonsil surface that are lined with reticulated epithelium infiltrated by immune cells. As in cervical HPV infections, HPV16 is the most prevalent high-risk type in the oropharyngeal cancers, and a genital-oral route of infection is most likely. However, the natural history of HPV-driven oropharyngeal pathogenesis is an enigma, although there is evidence that it is different to that of cervical disease. It is not known if the virus establishes a productive or abortive infection in keratinocytes of the tonsil crypt, or if viral infections progress to cancer via a neoplastic phase, as in cervical HPV infection. The HPV DNA is more frequently found unintegrated in the cancers of the oropharynx compared to those that arise in the cervix, and may include novel HPV-human DNA hybrids episomes. Here, we review current understanding of HPV biology in the oropharynx and discuss the cell-based systems being used to model the HPV life cycle in tonsil keratinocytes and how they can be used to inform on HPV-driven neoplastic progression in the oropharynx.

This article is part of the theme issue ‘Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses’.

Establishment and characterization of the pig tonsil epithelial (PT) cell line as a new model for persist infection of Japanese Encephalitis Virus

Japanese encephalitis virus (JEV) causes a serious zoonotic disease worldwide, pig is the reservoir and amplifying host of JEV. JEV can persist infect tonsil in pig, but the relation between persist infection in tonsil and reservoir are not clear until now. A stable pig tonsil cell line is necessary for JEV persist infection research. In this study, we established a continuous epithelial cell line, named PT cell, from the pig tonsil. This cell is susceptible to JEV. We determined the growth characteristics, molecular properties, microstructure profiles of PT cell. JEV is easy to enter PT cell which may partly explain the reason of persist infection. We further determined that LMAN2L, a mannose lectin proteins, is the primary viral receptors for JEV entry in PT cell. IFITM3, an cellular surface antiviral factor, is underexpression in PT cell after JEV infection. All these results provide solid evidence that PT cell will promote additional research on JEV persist infection in pig tonsil.

In vivo intratumoral Epstein-Barr virus replication is associated with XBP1 activation and early-onset post-transplant lymphoproliferative disorders with prognostic implications

Post-transplant lymphoproliferative disorders are life-threatening complications following hematopoietic or solid organ transplantation. They represent a spectrum of mostly EBV-driven lymphoplasmacytic proliferations. While the oncogenic effect of EBV is related to latent infection, lytic infection also has a role in lymphomagenesis. In vitro, EBV replication is linked to plasma cell differentiation and XBP1 activation, although this phenomenon has never been addressed in vivo. We analyzed for the first time latent and lytic intratumoral EBV infection in a series of 35 adult patients with a diagnosis of post-transplant lymphoproliferative disorder (26M/9F, median age 54 years). A complete EBV study was performed including the analysis of the latent EBER, latent membrane protein-11, and EBV nuclear antigens as well as the immediate-early BZLF1/ZEBRA and early BMRF1/EADE31 lytic genes. XBP1 activation was assessed by nuclear protein expression. EBV infection was observed in 28 (80%) cases being latency II and III the most frequently observed 22 (79%). Intratumoral EBV replication was detected in 17 (60%) cases. Among these, XBP1 activation was observed in 11/12 evaluable cases associated with strong cytoplasmic immunoglobulin expression consistent with plasma cell differentiation. Intriguingly, the combination of latency III infection and EBV replication identified a high-risk subgroup of patients with significantly shorter survival (overall survival at 1 year 18% vs 48%) and early-onset (median of 7 vs 26 months) post-transplant lymphoproliferative disorder. Moreover, these patients appear to be more heavily immunosuppressed, so they exhibit lower rates of rejection and graft vs host disease but higher rates of cytomegalovirus reactivation. In conclusion, EBV replication is associated with plasma cell differentiation and XBP1 activation with prognostic implications. Both latency III and lytic EBV infection are related to aggressive and early-onset post-transplant lymphoproliferative disorder. These results suggest that immunohistochemical study of latent and lytic EBV genes in the clinical practice may help to select higher-risk patients to new therapies including antiviral treatments.