LSPR based on-chip detection of dengue NS1 antigen in whole blood

The development of a biosensor for rapid and quantitative detection of the dengue virus continues to remain a challenge. We report a lab-on-chip device that combines membrane-based blood plasma separation and a localized surface plasmon resonance (LSPR) based biosensor for on-chip detection of dengue NS1 antigen from a few drops of blood. The LSPR effect is realized by irradiating UV-NIR light having a spectral peak at 655 nm onto nanostructures fabricated via thermal annealing of a thin metal film. We study the effect of the resulting metal nanostructures on the LSPR performance in terms of sensitivity and limit of detection, by annealing silver films at temperatures ranging from 100 to 500 °C. The effect of annealing temperature on the nanostructure size and uniformity and the resulting optical characteristics are investigated. Further, the binding between non-targeted blood plasma proteins and NS1-antibody-functionalized nanostructures on the LSPR performance is studied by considering different blocking mechanisms. Using a nanostructure annealed at 200 °C and 2X-phosphate buffer saline with 0.05% Tween-20 as the blocking buffer, from 10 μL of whole blood, the device can detect NS1 antigen at a concentration as low as 0.047 μg mL⁻¹ within 30 min. Finally, we demonstrate the detection of NS1 in the blood samples of dengue-infected patients and validate our results with those obtained from the gold-standard ELISA test.

A lab-on-chip device that combines membrane-based blood plasma separation and a localized surface plasmon resonance (LSPR) based biosensor for on-chip detection of dengue NS1 antigen from a few drops of blood.     

Fibroblast activation protein: Purification,epitope mapping and induction by growth factors

The human fibroblast activation protein (FAP) defined by monoclonal antibody (MAb) F19 is a cell surface antigen expressed in reactive stromal fibroblasts of breast, colorectal, lung and other epithelial cancers. In contrast to its stroma-specific localization in epithelial neoplasms, FAP is expressed in the malignant mesenchymal cells of bone and soft-tissue sarcomas. FAP is transiently expressed in some fetal mesenchymal tissues but is absent or expressed at low levels in most adult tissues. FAP is induced in cultured fibroblasts and, in these cells, consists of a M_r 95,000 subunit (FAPα) carrying the F19 epitope and a non-covalently bound M_r 105,000 subunit (FAPβ) lacking the F19 epitope. Using MAb F19 and 5 newly derived MAbs, we identify 3 distinct epitopes on FAPα and tentatively assign one epitope to FAPβ. Analysis of detergent extracts of a FAPα^highβ-sarcoma cell line by size exclusion–high performance liquid chromatography (HPLC) revealed that FAPα does not elute as a M_r, 95,000 species but as part of a high-molecular weight complex (M_r > 400,000) that dissociates into M_r 95,000 subunits in SDS gels. Immunoaffinity purification of FAPα followed by tryptic digestion, reversed-phase HPLC and microsequencing identified 3 unique FAPα peptides, with 2 showing sequence similarity (23/38 identical amino acids) to segments of CD26, a T-cell activation antigen. CD26 is a membrane-bound enzyme (dipeptidyl aminopeptidase IV), but immunopurified FAPα has little if any dipeptidase activity with typical CD26 substrates. Finally, studies with FAP^low leptomeningeal fibroblasts revealed that transforming growth factor-β, 12-O-tetradecanoyl phorbol-13-acetate and retinoids can upregulate FAP expression, whereas serum and several other factors had no or little effect on FAP levels. FAP and CD26 may belong to a family of structurally related but functionally distinct activation proteins that are expressed on different cell types and show unique modes of regulation in normal and malignant cells.     

Response to: Human papillomavirus (HPV) vaccine safety concerning POTS,CRPS and related conditions

Clinical Autonomic Research -     

Primary pancreatic lymphoma-diagnosed on computed tomography: A rare case report.

Primary pancreatic lymphoma is a rare disease. It comprises less than 0.5 % of pancreatic neoplasm and 0.1% of malignant lymphoma. It should be differentiated from pancreatic adenocarcinoma because management differs. At computed tomography, 2 types of morphology of primary pancreatic lymphoma have been described- a localized well-circumscribed tumoral form and another diffuse enlargement infiltrating or replacing most of the pancreatic gland. Here, we are presenting computed tomography (CT) imaging features of a case of primary pancreatic lymphoma in a 27 year old female who presented with a complaint of abdominal pain radiating to the back for 3 months and yellowish discoloration of sclera and skin for the last 15 days. In contrast-enhanced computed tomography an exophytic homogenously hypoenhancing mass arising from head and neck region of pancreas was seen. Involvement of common bile duct (CBD) and duodenum was there. The main pancreatic duct was not dilated. Common hepatic artery was encased by mass without arterial luminal narrowing or distortion. Diagnosis of primary pancreatic lymphoma was suggested on basis of imaging findings and further confirmed with fine-needle aspiration cytology.     

Epidemiology and Genetic Diversity of PCV2 Reveals That PCV2e Is an Emerging Genotype in Southern China: A Preliminary Study

Porcine circovirus-associated disease (PCVAD), caused by porcine circovirus type 2 (PCV2), has ravaged the pig industry, causing huge economic loss. At present, PCV2b and PCV2d are highly prevalent genotypes worldwide, while in China, in addition to PCV2b and PCV2d, a newly emerged PCV2e genotype detected in the Fujian province has attracted attention, indicating that PCV2 genotypes in China are more abundant. A preliminary study was conducted to better understand the genetic diversity and prevalence of PCV2 genotypes in southern China. We collected 79 random lung samples from pigs with respiratory signs, from 2018 to 2021. We found a PCV2-positivity rate of 29.1%, and frequent co-infections of PCV2 with PCV3, Streptococcus suis (S. suis), and other porcine pathogens. All PCV2-positive samples were sequenced and subjected to whole-genome analysis. Phylogenetic analysis, based on the PCV2 ORF2 gene and complete genomes, found that PCV2 strains identified in this study belonged to genotypes PCV2a (1), PCV2b (6), PCV2d (10), and PCV2e (6). Importantly, PCV2e was identified for the first time in some provinces, including Guangdong and Jiangxi. Additionally, we found two positively selected sites in the ORF2 region, located on the previously reported antigenic epitopes. Moreover, codon 63, one of the positively selected sites, has different types of amino acids in different genotypes. In conclusion, this study shows that PCV2e is an emerging genotype circulating in southern China, which warrants urgent, specific surveillance to aid the development of prevention and control strategies in China.     

HIV and Substance Use Stigma,Intersectional Stigma and Healthcare Among HIV-Positive PWID in Russia

AIDS and Behavior - Little is known about the intersection of HIV stigma and substance use stigma. Using data from 188 HIV-positive people who inject drugs (PWID) in Russia, we examined the...     

Structure-guided engineering of tick evasins for targeting chemokines in inflammatory diseases

As natural chemokine inhibitors, evasin proteins produced in tick saliva are potential therapeutic agents for numerous inflammatory diseases. Engineering evasins to block the desired chemokines and avoid off-target side effects requires structural understanding of their target selectivity. Structures of the class A evasin EVA-P974 bound to human CC chemokine ligands 7 and 17 (CCL7 and CCL17) and to a CCL8-CCL7 chimera reveal that the specificity of class A evasins for chemokines of the CC subfamily is defined by conserved, rigid backbone–backbone interactions, whereas the preference for a subset of CC chemokines is controlled by side-chain interactions at four hotspots in flexible structural elements. Hotspot mutations alter target preference, enabling inhibition of selected chemokines. The structure of an engineered EVA-P974 bound to CCL2 reveals an underlying molecular mechanism of EVA-P974 target preference. These results provide a structure-based framework for engineering evasins as targeted antiinflammatory therapeutics.

While some proteins exhibit absolute specificity for a unique binding partner, many others display “multispecificity,” whereby they interact with several, but not all, members of a partner protein family (1, 2). Understanding how proteins achieve such selectivity provides a basis for rational engineering to regulate alternative targets. In this study, we investigated the structural basis for multispecific recognition of human proinflammatory chemokines by tick evasin proteins.Chemokines are the master regulators of leukocyte-trafficking, the unifying feature of immune homeostasis and all inflammatory diseases (3). Chemokines stimulate leukocyte migration via activation of chemokine receptors, G protein–coupled receptors expressed on the surfaces of leukocytes. Chemokines are classified into two major families (CCL and CXCL) and two minor families (XCL and CX₃CL) based on the arrangement of conserved cysteine residues near the N termini of their amino acid sequences. Chemokine receptors are classified (CCR, CXCR, XCR, and CX₃CR) based on their chemokine selectivity. The types of leukocytes recruited to specific tissues depend on the array of chemokines expressed in those tissues and the selectivity of those chemokines for the receptors expressed on different leukocyte subsets. For example, in vascular inflammation associated with hypertension, elevated levels of the chemokines CCL2, CCL7, and CCL8 act via the receptor CCR2 (and possibly also CCR1) to stimulate migration of monocytes into the blood vessel wall (4).To suppress leukocyte recruitment in inflammatory diseases, numerous antagonists of specific chemokine receptors have been evaluated in clinical trials. However, these trials have not yielded any new antiinflammatory therapeutics (5), in part because most leukocytes can utilize multiple chemokine receptors, thus circumventing the specific antagonists. The alternative approach of targeting chemokines has not generally been favored, because it would require agents that bind with high affinity to multiple chemokines. However, the natural chemokine-binding proteins of ticks, helminths, and viruses (6–8) display multispecificity for mammalian chemokines, suggesting that they could potentially be deployed as antiinflammatory therapeutics.Evasins are two families of chemokine-binding, antiinflammatory proteins from tick saliva (6). Class A evasins each inhibit multiple CC chemokines of their mammalian hosts but none of the closely related CXC chemokines. Conversely, class B evasins are specific for CXC over CC chemokines but exhibit variable selectivity among CXC chemokines. Typically, each tick species secretes a mixture of evasins, thereby accomplishing broad-spectrum suppression of the host inflammatory response, presumably enabling the tick to feed on the host for extended periods.The in vivo antiinflammatory activity of tick evasins has been demonstrated using a variety of animal models of inflammatory diseases, including lung fibrosis, skin inflammation, arthritis, colitis, pancreatitis, ischemic reperfusion injury, postinfarction myocardial injury, and Leishmania major infection (9–13). However, deploying evasins as effective antiinflammatory therapeutics in humans would require engineering the natural evasins to selectively target the relevant array of chemokines for any given indication while minimizing off-target inhibition (14). Such engineering requires understanding both the specificity of evasins for a single chemokine subfamily and their target preference among chemokines within that subfamily.Previously, only a single structure has been reported for an evasin:chemokine complex, class A evasin EVA-1 bound to CCL3 (15), so it has not been possible to identify the conserved and variable features of the interactions. Nevertheless, the structure revealed that EVA-1 binds to several receptor recognition elements of CCL3, explaining its inhibitory activity. Moreover, limited mutational data (15, 16) have confirmed that residues in the N- and C-terminal regions of EVA-1 and the homologous EVA-4, respectively, contribute to binding affinity, raising the question of whether the structural basis of CC chemokine recognition varies across the class A evasin family.To establish a structure-based platform for engineering the chemokine selectivity of class A evasins, we now report the structures of EVA-P974 (previously called ACA-01) (17, 18), from the Cayenne tick (Amblyomma cajennense), bound to each of two wild-type chemokines and one chimeric CC chemokine. Structural comparisons and extensive evasin and chemokine mutational data revealed the structural basis for CC chemokine specificity and identified several “hotspots” that define target preference among CC chemokines. These insights enabled EVA-P974 to be engineered to modify its target preference. We further verified the molecular basis of the modified selectivity by solving the chemokine-bound structure of the engineered evasin. Finally, by inhibiting a chemokine mixture, we provide proof of principle for applying engineered evasins as multichemokine inhibitors.