Detection and Neutralization of SARS-CoV-2 Using Non-conventional Variable Lymphocyte Receptor Antibodies of the Evolutionarily Distant Sea Lamprey

SARS-CoV-2 is a newly emerged betacoronavirus and the causative agent for the COVID-19 pandemic. Antibodies recognizing the viral spike protein are instrumental in natural and vaccine-induced immune responses to the pathogen and in clinical diagnostic and therapeutic applications. Unlike conventional immunoglobulins, the variable lymphocyte receptor antibodies of jawless vertebrates are structurally distinct, indicating that they may recognize different epitopes. Here we report the isolation of monoclonal variable lymphocyte receptor antibodies from immunized sea lamprey larvae that recognize the spike protein of SARS-CoV-2 but not of other coronaviruses. We further demonstrate that these monoclonal variable lymphocyte receptor antibodies can efficiently neutralize the virus and form the basis of a rapid, single step SARS-CoV-2 detection system. This study provides evidence for monoclonal variable lymphocyte receptor antibodies as unique biomedical research and potential clinical diagnostic reagents targeting SARS-CoV-2

A novel functional approach toward identifying definitive drug targets

The process of developing drugs dates to antiquity. The herbal formulations during the old days were more traditional than with any scientific rationale. As different branches of physics, chemistry and biology started revealing the physiological processes in molecular details and as the sophisticated methods for probing into these phenomena were innovated, the processes of drug development changed significantly. However, the very first step in the process which is defining a drug target remains a major hurdle. The classical methods that predate the functional genomics and proteomics involve a cumbersome, painstaking detailing of a given enzyme or a receptor, followed by its validation as a target. The sophisticated methods in the post-genomic and proteomic era reduced the time taken to define targets, but the speed of drug discovery is not necessarily as quick as it promised. This is primarily due to prolific predictions pressing validation too hard, although both non-robotic and robotic high throughput screenings match with the requirement. Since these drugs target pathogens, a serious disadvantage with these methodologies is the emergence of drug resistance. Therefore, we propose a functional approach whereby the host-pathogen interaction is studied to find out the alterations in immune responses, the profile of host gene expression and activation of cell signaling molecules, the kinases in particular. Such interactions often induce the expression of those genes and activation of those proteins which are required for their survival. We demonstrate that reversal of such profiles of gene expression and protein activation ameliorates the infection. Therefore, those gene products and the kinases with pro-parasitic functions can serve as targets

Functional paradox in host-pathogen interaction dictates the fate of parasites

The interactions between the protozoan parasite Leishmania and host macrophages are complex and involve several paradoxical functions that are meant for protection of the host but exploited by the parasite for its survival. The initial interaction of the parasite surface molecules with the host-cell receptors plays a major role in the final outcome of the disease state. While the interactions between macrophages and a virulent strain of Leishmania trigger a cascade of cell-signaling events leading to immunosuppression, the interaction with an avirulent strain triggers host-protective immune effector functions. Thus, an incisive study on Leishmania-macrophage interactions reveals functional paradoxes that highlight the concept of 'relativity in parasite virulence'. Using Leishmania infection as a model, we propose that virulence of a pathogen and the resistance (or susceptibility) of a host to the pathogen are relative properties that equate to combinatorial functions of several sets of molecular processes

Effects of the phytoestrogen genistein on the development of the reproductive system of Sprague Dawley rats

OBJECTIVES: Genistein is known to influence reproductive system development through its binding affinity for estrogen receptors. The present study aimed to further explore the effect of Genistein on the development of the reproductive system of experimental rats. METHODS: Eighteen post-weaning female Sprague Dawley rats were divided into the following groups: (i) a control group that received vehicle (distilled water and Tween 80); (ii) a group treated with 10 mg/kg body weight (BW) of Genistein (Gen 10); and (iii) a group treated with a higher dose of Genistein (Gen 100). The rats were treated daily for three weeks from postnatal day 22 (P22) to P42. After the animals were sacrificed, blood samples were collected, and the uteri and ovaries were harvested and subjected to light microscopy and immunohistochemical study. RESULTS: A reduction of the mean weekly BW gain and organ weights (uteri and ovaries) were observed in the Gen 10 group compared to the control group; these findings were reversed in the Gen 100 group. Follicle stimulating hormone and estrogen levels were increased in the Gen 10 group and reduced in the Gen 100 group. Luteinizing hormone was reduced in both groups of Genistein-treated animals, and there was a significant difference between the Gen 10 and control groups (p<0.05). These findings were consistent with increased atretic follicular count, a decreased number of corpus luteum and down-regulation of estrogen receptors-a in the uterine tissues of the Genistein-treated animals compared to the control animals. CONCLUSION: Post-weaning exposure to Genistein could affect the development of the reproductive system of ovarian-intact experimental rats because of its action on the hypothalamic-pituitary-gonadal axis by regulating hormones and estrogen receptors

Detection of Human CD38 Using Variable Lymphocyte Receptor (VLR) Tetramers

CD38 is a multifunctional cell surface receptor expressed on multiple cell lineages of hematopoietic origin with high levels of expression on human plasma cells. Previously, we isolated the monoclonal variable lymphocyte receptor B (VLRB) MM3 antibody from the evolutionarily distant sea lamprey, which recognized the CD38 ectoenzyme exclusively on human plasma cells in a manner that correlated with CD38 enzymatic activity. The plasma cell-specific binding of VLRB MM3 contrasts with the broad pattern of expression of CD38-determined conventional antibodies specific for this antigen. In an effort to facilitate the application of this unique reagent in combination with conventional antibody panels, we explored a strategy to generate VLRB MM3 tetramers. The resulting reagent maintained the threshold-based recognition of CD38. Increased sensitivity achieved with VLRB MM3 tetramers also showed preferential recognition of germinal center centroblasts over centrocytes. VLRB MM3 tetramers thus provided a unique and versatile single-step staining reagent for the detection of human CD38 that is readily incorporated into multi-color flow cytometry panels

Detection of Human CD38 Using Variable Lymphocyte Receptor (VLR) Tetramers

CD38 is a multifunctional cell surface receptor expressed on multiple cell lineages of hematopoietic origin with high levels of expression on human plasma cells. Previously, we isolated the monoclonal variable lymphocyte receptor B (VLRB) MM3 antibody from the evolutionarily distant sea lamprey, which recognized the CD38 ectoenzyme exclusively on human plasma cells in a manner that correlated with CD38 enzymatic activity. The plasma cell-specific binding of VLRB MM3 contrasts with the broad pattern of expression of CD38-determined conventional antibodies specific for this antigen. In an effort to facilitate the application of this unique reagent in combination with conventional antibody panels, we explored a strategy to generate VLRB MM3 tetramers. The resulting reagent maintained the threshold-based recognition of CD38. Increased sensitivity achieved with VLRB MM3 tetramers also showed preferential recognition of germinal center centroblasts over centrocytes. VLRB MM3 tetramers thus provided a unique and versatile single-step staining reagent for the detection of human CD38 that is readily incorporated into multi-color flow cytometry panels

Guidelines for the use of flow cytometry and cell sorting in immunological studies

International audienceThe classical model of hematopoiesis established in the mouse postulates that lymphoid cells originate from a founder population of common lymphoid progenitors. Here, using a modeling approach in humanized mice, we showed that human lymphoid development stemmed from distinct populations of CD127(-) and CD127(+) early lymphoid progenitors (ELPs). Combining molecular analyses with in vitro and in vivo functional assays, we demonstrated that CD127(-) and CD127(+) ELPs emerged independently from lympho-mono-dendritic progenitors, responded differently to Notch1 signals, underwent divergent modes of lineage restriction, and displayed both common and specific differentiation potentials. Whereas CD127(-) ELPs comprised precursors of T cells, marginal zone B cells, and natural killer (NK) and innate lymphoid cells (ILCs), CD127(+) ELPs supported production of all NK cell, ILC, and B cell populations but lacked T potential. On the basis of these results, we propose a "two-family" model of human lymphoid development that differs from the prevailing model of hematopoiesis