Suchergebnisse

To establish latent infections in B-cells, gammaherpesviruses express proteins in the infected B-cells of the host that spuriously activate signalling pathways located downstream of the B-cell receptor. One such protein is M2, a murine gammaherpesvirus 68-encoded molecule that activates the Vav1/Rac1 pathway via the formation of trimolecular complexes with Scr family members. Previous reports have shown that the formation of this heteromolecular complex involves interactions between a proline rich region of M2 and the Vav1 and Fyn SH3 domains. Here, we show that the optimal association of these proteins requires a second structural motif encompassing two tyrosine residues (Tyr120 and 129). These residues are inducibly phosphorylated by Fyn in non-hematopoietic cells and constitutively phosphorylated in B-cells. We also demonstrate that the phosphorylation of Tyr120 creates specific docking sites for the SH2 domains of both Vav1 and Fyn, a condition sine qua non for the optimal association of these two signalling proteins in vivo. Interestingly, signaling experiments indicate that the expression of M2 in B-cells promotes the tyrosine phosphorylation of Vav1 and additional signaling proteins, a biological process that requires the integrity of both the M2 phosphotyrosine and proline rich region motifs. By infecting mice with viruses mutated in the m2 locus, we show that the integrity of each of these two M2 docking motifs is essential for the early steps of murine gammaherpesvirus-68 latency. Taken together, these results indicate that the M2 phosphotyrosine motif and the previously described M2 proline rich region work in a concerted manner to manipulate the signaling machinery of the host B-cell. ; This work was supported by a grant to J.P.S. from the Portuguese Fundação para a Ciência e Tecnologia (POCI/SAU-IMI/57365/2004). X.R.B.'s work is supported by grants from the US National Cancer Institute/NIH (5R01-CA73735-11), the Spanish Ministry of Education and Science (MES) (SAF2006-01789), the Castilla-León Autonomous Government (SA053A05), and the Red Temática de Investigación Cooperativa en Cáncer (RTICC) (RD06/0020/0001, Fondo de Investigaciones Sanitarias (FIS), Carlos III Institute, Spanish Ministry of Health). All Spanish funding is co-sponsored by the European Union FEDER program. M.P.M., M.A., S.M., L.R. and F.L. were recipients of fellowships from the Fundação para a Ciência e Tecnologia. ; Peer reviewed

© 2020 The Authors. European Journal of Immunology published by Wiley‐VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ; SARS-CoV-2 has emerged as a human pathogen, causing clinical signs, from fever to pneumonia-COVID-19-but may remain mild or asymptomatic. To understand the continuing spread of the virus, to detect those who are and were infected, and to follow the immune response longitudinally, reliable and robust assays for SARS-CoV-2 detection and immunological monitoring are needed. We quantified IgM, IgG, and IgA antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) or the Spike (S) protein over a period of 6 months following COVID-19 onset. We report the detailed setup to monitor the humoral immune response from over 300 COVID-19 hospital patients and healthcare workers, 2500 University staff, and 198 post-COVID-19 volunteers. Anti-SARS-CoV-2 antibody responses follow a classic pattern with a rapid increase within the first three weeks after symptoms. Although titres reduce subsequently, the ability to detect anti-SARS-CoV-2 IgG antibodies remained robust with confirmed neutralization activity for up to 6 months in a large proportion of previously virus-positive screened subjects. Our work provides detailed information for the assays used, facilitating further and longitudinal analysis of protective immunity to SARS-CoV-2. Importantly, it highlights a continued level of circulating neutralising antibodies in most people with confirmed SARS-CoV-2. ; We like to acknowledge the funding from the European Union H2020 ERA project (No 667824 – EXCELLtoINNOV) and the Fundação para a Ciência e a Tecnologia (FCT) to P.F‐C. (SFRH/BD/131605/2017), PTDC/MED‐IMU/28003/2017, and research4COVID19 (no. 231_596873172, Generating SARS‐CoV2 seroconversion assay and no. 729, High‐throughput SARS‐CoV2 neutralizing antibodies assessment), with ...