A multifunctional human monoclonal neutralizing antibody that targets a unique conserved epitope on influenza HA

The high rate of antigenic drift in seasonal influenza viruses necessitates frequent changes in vaccine composition. Recent seasonal H3 vaccines do not protect against swine-origin H3N2 variant (H3N2v) strains that recently have caused severe human infections. Here, we report a human VH1-69 gene-encoded monoclonal antibody (mAb) designated H3v-47 that exhibits potent cross-reactive neutralization activity against human and swine H3N2 viruses that circulated since 1989. The crystal structure and electron microscopy reconstruction of H3v-47 Fab with the H3N2v hemagglutinin (HA) identify a unique epitope spanning the vestigial esterase and receptor-binding subdomains that is distinct from that of any known neutralizing antibody for influenza A H3 viruses. MAb H3v-47 functions largely by blocking viral egress from infected cells. Interestingly, H3v-47 also engages Fcγ receptor and mediates antibody dependent cellular cytotoxicity (ADCC). This newly identified conserved epitope can be used in design of novel immunogens for development of broadly protective H3 vaccines

Clinicopathological and Immunohistochemical Profile of Malignant Surface Epithelial Ovarian Tumors

Background and Objectives: Ovary is a complex organ in terms of its embryology, Histology, Steroidogenesis and malignancy. Histomorphological study of ovarian tumors is undertaken with the aim of studying age distribution and histomorphological characterization of ovarian tumors. Material and methods: The study is undertaken for the period of 2 yrs. From August 2015 to July 2017 prospectively at the Upgraded Department of Pathology, Osmania Medical college. All the specimens of ovarian tumours received were subjected to routine processing and histopathological examination. Results: Total numbers of 80 cases were studied. Among these 38 cases (51.6%) were Benign tumours, 9 cases (17.5%) were Borderline tumors and 25 (31.5%) cases were malignant. Benign neoplasms peaked in 4th decade and Malignant in 5th decade. The serous surface epithelial tumors were the Commonest among other surface epithelial tumors.Conclusion: Benign surface epithelial tumours are the most prevalent type in this study. Categorization will help in the accurate diagnosis and subsequent treatment

Spinal Dysraphism-Histopathological Study of 45 Cases

Introduction: Dysraphic conditions of spine resulting from nonclosure of the neural groove, consists of different types of malformations and they are called spina bifida, which have been classified into several types. Myelomeningocele (MMC) and Meningocele (MC) come under spina bifida cystica. Aim: Aim of the study was to review the clinical and pathological findings of congenital spinal dysraphism and discuss the pathological diagnosis Materials and Methods: A descriptive cross-sectional type of study was conducted in 45 cases of spinal dysraphism during the period from Oct 2012 to Feb 2016, in the department of pathology of a tertiary care hospital, Hyderabad. Cases which were diagnosed as spinal dysraphism by clinical and radiological examination, tissue specimens were sent to the department of pathology along with clinical and radiological findings. H&E staining was done in all cases, followed by detailed microscopic study of slides. Histopathological findings such as epithelial, mesodermal, neuroectodermal changes were elucidated in detail and findings were compared with literature. Results: In a total of 45 cases there were 30 cases of MMC, nine cases of MC, six cases of encephalocele. Loss of epidermal appendages seen in 91% of cases and neuropil like matrix was present in 76% cases. Conclusion: The embryogenesis of spina bifida involves ectoderm, neuroectoderm and mesoderm. A detailed definition of histopathological aspects will help in understanding these anomalies and should be a part of a detailed histopathology report

Stromal expression of cd10 in invasive breast carcinoma and its correlation with ER, PR, HER2, NEU and KI67

Aim & Objective: To evaluate and correlate CD10 expression with ER, PR, HER2-Neu & Ki 67 index CD 10 expression in breast malignancies. Methodology : The descriptive study was undertaken in the Upgraded Department of Pathology, Osmania medical college, Hyderabad from Dec 2015 to June 2017.Total of 50 cases of invasive breast carcinomas in females were included in the study. Of these 45 cases comprised of invasive carcinoma of no special type (NST) followed by 3 cases of invasive lobular carcinoma and the remaining 2 cases were medullary carcinoma and tubular carcinoma respectively. Results: In the present study, the age group included were from 35-80 years with the average age being 51years and highest incidence of breast carcinoma was seen in fourth decade. Routine processing and Haematoxylin and Eosin staining of the received specimens were done followed by immunohistochemical analysis with CD10, ER, PR, HER2neu & Ki 67 antibody was done. In the present study, cytoplasmic and membranous staining of >30% of the stromal cells around the tumor cells were taken as CD 10 stromal positivity. CD 10 stromal positivity was correlated with expression of ER, PR, HER2 neu and Ki 67 index. Present study showed a slight lower negative correlation of CD10 stromal expression with ER expression which showed a higher correlation in other studies. This discordance can be attributed to the number of cases and duration of study and also to the more ER positive prevalence in the study group. Present study did not show any correlation with CD 10 expression and PR status which was much similar to the observations in other studies. Present study showed good correlation between stromal CD 10 expression and well established negative prognostic marker that is, HER2 neu overexpression and high Ki 67 index. Conclusion: To conclude, stroma plays a important role in progression, hormonal expression and response to chemotherapy in breast cance

Potent anti-influenza H7 human monoclonal antibody induces separation of hemagglutinin receptor-binding head domains.

Seasonal influenza virus infections can cause significant morbidity and mortality, but the threat from the emergence of a new pandemic influenza strain might have potentially even more devastating consequences. As such, there is intense interest in isolating and characterizing potent neutralizing antibodies that target the hemagglutinin (HA) viral surface glycoprotein. Here, we use cryo-electron microscopy (cryoEM) to decipher the mechanism of action of a potent HA head-directed monoclonal antibody (mAb) bound to an influenza H7 HA. The epitope of the antibody is not solvent accessible in the compact, prefusion conformation that typifies all HA structures to date. Instead, the antibody binds between HA head protomers to an epitope that must be partly or transiently exposed in the prefusion conformation. The "breathing" of the HA protomers is implied by the exposure of this epitope, which is consistent with metastability of class I fusion proteins. This structure likely therefore represents an early structural intermediate in the viral fusion process. Understanding the extent of transient exposure of conserved neutralizing epitopes also may lead to new opportunities to combat influenza that have not been appreciated previously

A natural mutation between SARS-CoV-2 and SARS-CoV determines neutralization by a cross-reactive antibody.

Epitopes that are conserved among SARS-like coronaviruses are attractive targets for design of cross-reactive vaccines and therapeutics. CR3022 is a SARS-CoV neutralizing antibody to a highly conserved epitope on the receptor binding domain (RBD) on the spike protein that is able to cross-react with SARS-CoV-2, but with lower affinity. Using x-ray crystallography, mutagenesis, and binding experiments, we illustrate that of four amino acid differences in the CR3022 epitope between SARS-CoV-2 and SARS-CoV, a single mutation P384A fully determines the affinity difference. CR3022 does not neutralize SARS-CoV-2, but the increased affinity to SARS-CoV-2 P384A mutant now enables neutralization with a similar potency to SARS-CoV. We further investigated CR3022 interaction with the SARS-CoV spike protein by negative-stain EM and cryo-EM. Three CR3022 Fabs bind per trimer with the RBD observed in different up-conformations due to considerable flexibility of the RBD. In one of these conformations, quaternary interactions are made by CR3022 to the N-terminal domain (NTD) of an adjacent subunit. Overall, this study provides insights into antigenic variation and potential cross-neutralizing epitopes on SARS-like viruses

An Alternative Binding Mode of IGHV3-53 Antibodies to the SARS-CoV-2 Receptor Binding Domain

IGHV3-53-encoded neutralizing antibodies are commonly elicited during SARS-CoV-2 infection and target the receptor-binding domain (RBD) of the spike (S) protein. Such IGHV3-53 antibodies generally have a short CDR H3 because of structural constraints in binding the RBD (mode A). However, a small subset of IGHV3-53 antibodies to the RBD contain a longer CDR H3. Crystal structures of two IGHV3-53 neutralizing antibodies here demonstrate that a longer CDR H3 can be accommodated in a different binding mode (mode B). These two classes of IGHV3-53 antibodies both target the ACE2 receptor binding site, but with very different angles of approach and molecular interactions. Overall, these findings emphasize the versatility of IGHV3-53 in this common antibody response to SARS-CoV-2, where conserved IGHV3-53 germline-encoded features can be combined with very different CDR H3 lengths and light chains for SARS-CoV-2 RBD recognition and virus neutralization

A site of vulnerability on the influenza virus hemagglutinin head domain trimer interface

Here, we describe the discovery of a naturally occurring human antibody (Ab), FluA-20, that recognizes a new site of vulnerability on the hemagglutinin (HA) head domain and reacts with most influenza A viruses. Structural characterization of FluA-20 with H1 and H3 head domains revealed a novel epitope in the HA trimer interface, suggesting previously unrecognized dynamic features of the trimeric HA protein. The critical HA residues recognized by FluA-20 remain conserved across most subtypes of influenza A viruses, which explains the Ab's extraordinary breadth. The Ab rapidly disrupted the integrity of HA protein trimers, inhibited cell-to-cell spread of virus in culture, and protected mice against challenge with viruses of H1N1, H3N2, H5N1, or H7N9 subtypes when used as prophylaxis or therapy. The FluA-20 Ab has uncovered an exceedingly conserved protective determinant in the influenza HA head domain trimer interface that is an unexpected new target for anti-influenza therapeutics and vaccines

Cross-Neutralization of a SARS-CoV-2 Antibody to a Functionally Conserved Site Is Mediated by Avidity

Most antibodies isolated from individuals with coronavirus disease 2019 (COVID-19) are specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, COVA1-16 is a relatively rare antibody that also cross-neutralizes SARS-CoV. Here, we determined a crystal structure of the COVA1-16 antibody fragment (Fab) with the SARS-CoV-2 receptor-binding domain (RBD) and negative-stain electron microscopy reconstructions with the spike glycoprotein trimer to elucidate the structural basis of its cross-reactivity. COVA1-16 binds a highly conserved epitope on the SARS-CoV-2 RBD, mainly through a long complementarity-determining region (CDR) H3, and competes with the angiotensin-converting enzyme 2 (ACE2) receptor because of steric hindrance rather than epitope overlap. COVA1-16 binds to a flexible up conformation of the RBD on the spike and relies on antibody avidity for neutralization. These findings, along with the structural and functional rationale for epitope conservation, provide insights for development of more universal SARS-like coronavirus vaccines and therapies