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Many phytopathogenic bacteria require a type three secretion system (TTSS) to activate effector triggered immunity (ETI). We identified a calcium binding protein, EfhXXfa, in the citrus pathogen, X. citri subsp. aurantifolii, that does not require a TTSS to activate reactive oxygen species (ROS) and elicit a hypersensitive reaction (HR) in tomato leaves following infection. Purified, recombinant EfhXXfa was shown to bind two moles of calcium per mole of protein, whereas mutation of the first of two EF-hands did not bind calcium . EfhXXfa expression was determined to be inducible in hrp-inducing medium. Additionally, growth of X. perforans transconjugants with and without the efhXXfa gene in hrp-inducing medium differed in intracellular calcium concentration; the transconjugant without efhXXfa yielded higher cell pellet masses and higher increased intracellular calcium concentrations relative to cells expressing EfhXXfa. An EfhXXfa homolog, EfhXXe, present in the pepper pathogen, X. euvesicatoria, when expressed in the tomato pathogen, X. perforans, triggered ROS production and an HR in tomato leaves and is a host-limiting factor. Interestingly, all tested X. perforans and X. euvesicatoria strains pathogenic on tomato contain a stop codon immediately upstream of the first EF-hand domain in the efhXXe gene, whereas most X. euvesicatoria strains pathogenic on pepper do not.
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Spiroplasma virus 4 (SpV4) is a bacteriophage of the Microviridae, which packages circular ssDNA within non-enveloped T = 1 icosahedral capsids. It infects spiroplasmas, which are known pathogens of honeybees. Here, the structure of the SpV4 virion is determined using cryo-electron microscopy to a resolution of 2.5 Å. A striking feature of the SpV4 capsid is the mushroom-like protrusions at the 3-fold axes, which is common among all members of the subfamily Gokushovirinae. While the function of the protrusion is currently unknown, this feature varies widely in this subfamily and is therefore possibly an adaptation for host recognition. Furthermore, on the interior of the SpV4 capsid, the location of DNA-binding protein VP8 was identified and shown to have low structural conservation to the capsids of other viruses in the family. The structural characterization of SpV4 will aid future studies analyzing the virus-host interaction, to understand disease mechanisms at a molecular level. Furthermore, the structural comparisons in this study, including a low-resolution structure of the chlamydia phage 2, provide an overview of the structural repertoire of the viruses in this family that infect various bacterial hosts, which in turn infect a wide range of animals and plants.
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Proteínas de la Cápside , Cápside , Microscopía por Crioelectrón , Microviridae , Spiroplasma , Virión , Cápside/ultraestructura , Cápside/metabolismo , Cápside/química , Proteínas de la Cápside/química , Proteínas de la Cápside/metabolismo , Proteínas de la Cápside/genética , Spiroplasma/ultraestructura , Microviridae/genética , Microviridae/ultraestructura , Microviridae/química , Virión/ultraestructura , Bacteriófagos/ultraestructura , Bacteriófagos/genética , Bacteriófagos/clasificación , Bacteriófagos/química , Bacteriófagos/fisiología , Modelos MolecularesRESUMEN
ABSTRACT: Patients who have had fractures are at increased risk for a second or fragility fracture. A fracture liaison service (FLS), often staffed or led by physician associates/assistants or NPs, may help reduce second fractures and patient mortality. This article reviews FLSs and their effectiveness.
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Osteoporosis , Fracturas Osteoporóticas , Humanos , Osteoporosis/complicaciones , Fracturas Osteoporóticas/prevención & control , Fracturas Osteoporóticas/etiología , Prevención Secundaria/métodos , Asistentes MédicosRESUMEN
Adeno-associated virus (AAV) serotypes from primates are being developed and clinically used as vectors for human gene therapy. However, the evolutionary mechanism of AAV variants is far from being understood, except that genetic recombination plays an important role. Furthermore, little is known about the interaction between AAV and its natural hosts, human and nonhuman primates. In this study, natural AAV capsid genes were subjected to systemic evolutionary analysis with a focus on selection drives during the diversification of AAV lineages. A number of positively selected sites were identified from these AAV lineages with functional relevance implied by their localization on the AAV structures. The selection drives of the two AAV2 capsid sites were further investigated in a series of biological experiments. These observations did not support the evolution of the site 410 of the AAV2 capsid driven by selection pressure from the human CD4+ T-cell response. However, positive selection on site 548 of the AAV2 capsid was directly related to host humoral immunity because of the profound effects of mutations at this site on the immune evasion of AAV variants from human neutralizing antibodies at both the individual and population levels. Overall, this work provides a novel interpretation of the genetic diversity and evolution of AAV lineages in their natural hosts, which may contribute to their further engineering and application in human gene therapy.
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Proteínas de la Cápside , Dependovirus , Evolución Molecular , Selección Genética , Dependovirus/genética , Dependovirus/inmunología , Humanos , Animales , Proteínas de la Cápside/genética , Proteínas de la Cápside/inmunología , Variación Genética , Terapia GenéticaRESUMEN
The viral interferon regulatory factors (vIRFs) of KSHV are known to dysregulate cell signaling pathways to promote viral oncogenesis and to block antiviral immune responses to facilitate infection. However, it remains unknown to what extent each vIRF plays a role in gene regulation. To address this, we performed a comparative analysis of the protein structures and gene regulation of the four vIRFs. Our structure prediction analysis revealed that despite their low amino acid sequence similarity, vIRFs exhibit high structural homology in both their DNA-binding domain (DBD) and IRF association domain. However, despite this shared structural homology, we demonstrate that each vIRF regulates a distinct set of KSHV gene promoters and human genes in epithelial cells. We also found that the DBD of vIRF1 is essential in regulating the expression of its target genes. We propose that the structurally similar vIRFs evolved to possess specialized transcriptional functions to regulate specific genes.
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Células Epiteliales , Regulación Viral de la Expresión Génica , Herpesvirus Humano 8 , Factores Reguladores del Interferón , Proteínas Virales , Humanos , Factores Reguladores del Interferón/metabolismo , Factores Reguladores del Interferón/genética , Herpesvirus Humano 8/genética , Herpesvirus Humano 8/fisiología , Células Epiteliales/virología , Proteínas Virales/metabolismo , Proteínas Virales/genética , Regiones Promotoras Genéticas , Transcripción Genética , Genoma Viral , Línea CelularRESUMEN
Parvovirus B19 (B19V) is a human pathogen that is the causative agent of several diseases in infants and adults. Due to a lack of antivirals against this virus, treatment options are limited. The minor capsid protein of B19V has a unique N terminus, named VP1u, which is essential for infection. The VP1u encodes a receptor binding domain (RBD), necessary for host cell entry, and a phospholipase A2 (PLA2) domain, crucial for endosomal escape during cellular trafficking. Both domains are indispensable for infection, making the RBD a plausible drug target for inhibitors against B19V, as it is located on the exterior surface of the virus. To date, no experimental structural information has been available for the VP1u component for any Parvovirus. Here we report the backbone NMR resonance assignments for the RBD of B19V and demonstrate it forms a stable structure. The backbone chemical shifts are in good agreement with a structure predicted by AlphaFold, validating that the RBD contains three helices connected by tight turns. This RBD construct can now be used for further NMR studies, including assignment of full-length VP1u, determination of protein-protein interaction interfaces, and development of B19 antivirals specific to the RBD domain. Database: BMRB submission code: 52440.
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Parvovirus B19 (B19V) is a human pathogen that is the causative agent of several diseases in infants and adults. Due to a lack of antivirals against this virus, treatment options are limited. The minor capsid protein of B19V has a unique N terminus, named VP1u, which is essential for infection. The VP1u encodes a receptor binding domain (RBD), necessary for host cell entry, and a phospholipase A2 (PLA2) domain, crucial for endosomal escape during cellular trafficking. Both domains are indispensable for infection, making the RBD a plausible drug target for inhibitors against B19V, as it is located on the exterior surface of the virus. To date, no experimental structural information has been available for the VP1u component for any Parvovirus. Here we report the backbone NMR resonance assignments for the RBD of B19V and demonstrate it forms a stable structure. The backbone chemical shifts are in good agreement with a structure predicted by AlphaFold, validating that the RBD contains three helices connected by tight turns. This RBD construct can now be used for further NMR studies, including assignment of full-length VP1u, determination of protein-protein interaction interfaces, and development of B19 antivirals specific to the RBD domain.
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Monoclonal antibodies (mAbs) are useful tools to dissect the neutralizing antibody response against the adeno-associated virus (AAV) capsids used as gene therapy delivery vectors. This study structurally characterizes the interactions of 21 human-derived antibodies from patients treated with the AAV9 vector, Zolgensma ® , utilizing high-resolution cryo-electron microscopy. The majority of the bound antibodies do not conform to the icosahedral symmetry of the capsid, thus requiring localized reconstructions. These complex structures provide unprecedented details of the mAbs binding interfaces, with some antibodies inducing structural perturbations of the capsid upon binding. Key surface capsid amino acid residues were identified facilitating the design of capsid variants with an antibody escape phenotype, with the potential to expand the patient cohort treatable with AAV9 vectors to include those that were previously excluded due to their pre-existing neutralizing antibodies, and possibly also to those requiring redosing.
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PURPOSE: Procedures are manual technical skills clinicians perform for their patients. Family physicians (FPs) acquire these skills during residency; most are undertaken in outpatient settings. We performed a retrospective observational cohort study to describe the extent to which FPs perform the core procedures recommended by the Council of Academic Family Medicine (CAFM) and how this might have changed over time. METHODS: The CAFM recommended a list of procedures all FP residents should perform competently after graduation. We modified this list for Medicare beneficiaries to enable matching with Current Procedural Terminology codes. We probed Medicare Part B databases for modified CAFM procedure claims submitted by FPs in 2021 and how these claims changed from 2014 to 2021. RESULTS: In 2021, there were 904,278 modified CAFM procedures filed by 9,410 FPs in the outpatient setting. All procedures were clustered with respect to organ system (eg, musculoskeletal, skin, pulmonary). Beginning in 2014 and continuously through 2021, there was a 33% decrease in outpatient procedures filed and a 36% decrease in the number of FPs filing them. CONCLUSIONS: Office-based procedures are integral to a primary care physician's role, although the activity is rarely analyzed. At a time when the Medicare population is growing, the number of available FPs and the number of procedures they perform are not. This decrease might result from the changing scope of FP practice, new referral patterns, task shifting, and/or increased delegation to physician associates and nurse practitioners.
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Medicina Familiar y Comunitaria , Humanos , Estados Unidos , Estudios Retrospectivos , Médicos de Familia/estadística & datos numéricos , Medicare , Competencia Clínica , Femenino , Masculino , Medicare Part BRESUMEN
OBJECTIVE: We hypothesized that physician associate (PA) and nurse practitioner (NP) procedural roles are expanding. We sought to describe ambulatory procedures these professionals performed in 2021 for older adults. STUDY DESIGN: Retrospective observational cohort study of Medicare Part B data. US Bureau of Labor Statistics data were used to provide overall PA and NP employment context. METHODS: Medicare Part B databases were probed for outpatient events by PAs and NPs using a modified list of the Council of Academic Family Medicine's recommended clinical procedures that focused on 29 procedures organized into 9 categories called procedure clusters. These procedures were linked to Current Procedural Terminology codes and PA and NP National Provider Identifier codes in Medicare Part B and then tabulated and analyzed for 2021. The Bureau of Labor Statistics provided NP and PA employment trends for context. The trend of the procedures and providers spanning 2014-2021 was analyzed. RESULTS: In 2021, 23,581 NPs and PAs filed 9.6 million Medicare Part B enrollee procedure claims. Most procedures (96%) involved skin or the musculoskeletal system. PAs filed more than twice as many claims for skin and musculoskeletal procedures as NPs, and NPs filed 1.25 times as many as PAs for the eye, ear, nose, and throat; pulmonary; genitourinary; gastrointestinal-colorectal; and women's health categories. From 2014 through 2021, the number of PAs and NPs in clinical practice increased by 72%, and the number of those who filed procedure claims increased by 74%. CONCLUSIONS: Overall, PAs performed more skin and musculoskeletal procedures than NPs, and NPs performed more procedures in the other 7 procedure clusters than PAs. PA and NP employment growth does not fully explain these observations. We suggest that outpatient procedural task-shifting activity presents an area for further research.
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Medicare Part B , Enfermeras Practicantes , Asistentes Médicos , Médicos , Anciano , Femenino , Humanos , Estudios Retrospectivos , Estados UnidosRESUMEN
Acetylation of key Lysine residues characterizes aggregates of the microtubule-associated protein tau constituting the neuropathological hallmark of many neurodegenerative diseases, such as Alzheimer's disease (AD) and Progressive Supranuclear Palsy (PSP). This has led to the idea that acetylation influences tau aggregation. Using a HEK293 cell-based aggregation assay, we tested whether acetylation-mimicking substitutions (KâQ) on five AD-associated acetyl-modified sites (AcK-311, 353, 369, 370, 375) influenced its propensity to aggregate when exposed to tau seeds derived from two clinically distinctive diseases - AD and PSP. In combination, the presence of 5KâQ sites ablated tau aggregation induced by seeds from both AD and PSP patients, indicating that acetylation within the filament core domain of tau could have an inhibitory effect on seed-mediated aggregation. We had previously identified that a phosphorylation-mimetic on Ser305 (SâE) abrogated tau aggregation by seeds from AD patients, without affecting seeding by PSP patients. Combining the S305âE to the 5KâQ acetyl-modified sites, we found that this tau could now be seeded only by PSP patients, but not by AD patients, confirming Ser305 as a critical determinant of strain-specific tau seeding. On the other hand, acetylation-nullifying substitutions (KâR or KâA) on these same Lys sites did not alter tau seeding abilities compared to the parental tau construct. Notably, the combined acetylation-nullifying Alanine substitutions on these 5 Lys sites resulted in spontaneous self-aggregation, with the filaments resembling amorphous deposits. All together, we demonstrate that cooperative acetyl-occupancy in the tau filament core influences seeded propagation of misfolded tau as well as drives self-aggregation.
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The combination of X-ray free-electron lasers (XFELs) with serial femtosecond crystallography represents cutting-edge technology in structural biology, allowing the study of enzyme reactions and dynamics in real time through the generation of `molecular movies'. This technology combines short and precise high-energy X-ray exposure to a stream of protein microcrystals. Here, the XFEL structure of carbonic anhydrase II, a ubiquitous enzyme responsible for the interconversion of CO2 and bicarbonate, is reported, and is compared with previously reported NMR and synchrotron X-ray and neutron single-crystal structures.
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Anhidrasa Carbónica II , Anhidrasa Carbónica II/química , Cristalografía por Rayos X , Proteínas/química , Sincrotrones , Rayos X , HumanosRESUMEN
To investigate the intrinsic relation between carbonic anhydrase inhibition and anticancer activity, we have prepared four sets of diaryl urea molecules and tested for the inhibition of hCA-IX and XII on two breast cancer cell lines. Among 21 compounds, compound J2 (with -SO2NH2 group) and J16 (without -SO2NH2 group) showed the best activity under normoxic and hypoxic conditions. The IC50 values of J16 for MDA-MB-231 and MCF-7 cells, under normoxic condition were 6.3 and 3.7 µM respectively, which are 1.9/3.3 and 15.8 times better than U-4-Nitro and SLC-0111 respectively. Whereas, under the hypoxic condition the corresponding values were 12.4 and 1.1 µM (MDA-MB-231 and MCF-7 cells respectively), which are equal/8 times better than U-4-Nitro. Whereas, J2 showed better IC50 value than U-4-Nitro (6.3 µM) under normoxic condition for both MDA-MB-231 and MCF-7 cells (1.9/2.7 times). Compound J2 inhibits the activity of hCA-IX and XII in nanomolar concentration [Ki values 4.09 and 9.10 nM respectively with selectivity ratio of 1.8 and 0.8 with hCA-II]. The crystal structure and modelling studies demonstrates that the inhibition of CAs arises due to the blocking of the CO2 coordination site of zinc in its catalytic domain. However, J16 was found to be unable to inhibit the activity of hCAs (Ki > 89000 nM). qPCR and western blot analysis showed a significant reduction (1.5 to 20 fold) of the transcription and expression of HIF1A, CA9 and CA12 genes in presence of J2 and J16. Both J2 and J16 found to reduce accumulation of HIF-1α protein by inhibiting the chaperone activity of hHSP70 with IC50 values of 19.4 and 15.3 µM respectively. Perturbation of the hCA-IX and XII activity by binding at active site or by reduced expression or by both leads to the decrease of intracellular pH, which resulted in concomitant increase of reactive oxygen species by 2.6/2.0 (MCF-7) and 2.9/1.8 (MDA-MB-231) fold for J2/J16. Increased cyclin D1 expression in presence of J2 and J16 was presumed to be indirectly responsible for the apoptosis of the cancer cells. Expression of the other apoptosis markers Bcl-2, Bim, caspase 9 and caspase 3 substantiated the apoptosis mechanism. However, decreased transcription/expression of HIF1A/HIF-1α and hCA-IX/XII also implies the inhibition of the extracellular signal-regulated kinase pathway by J2 and J16.
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Neoplasias de la Mama , Urea , Humanos , Femenino , Anhidrasa Carbónica IX , Relación Estructura-Actividad , Urea/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Antígenos de Neoplasias/metabolismo , Sulfonamidas/farmacología , Sulfonamidas/química , Inhibidores de Anhidrasa Carbónica/química , Estructura MolecularRESUMEN
INTRODUCTION: Parvovirus B19 (B19V) is a human pathogen, and the minor capsid protein of B19V possesses a unique N terminus called VP1u that plays a crucial role in the life cycle of the virus. OBJECTIVES: The objective of this study was to develop a method for domain segmentation of B19 VP1u using intein technology, particularly its receptor binding domain (RBD) and phospholipase A2 (PLA2) domain. METHODS: RBD and PLA2 domains of VP1u were each fused to the DnaE split inteins derived from the Nostoc punctiforme. Each of these precursor proteins was expressed in E. coli. Combining the purified precursors in equal molar ratios resulted in the formation of full-length VP1u. Furthermore, Circular Dichroism (CD) spectroscopy and PLA2 assays were used to probe the structure and activity of the newly formed protein. RESULTS: The CD spectrum of the full length VP1u confirmed the secondary structure of protein, while the PLA2 assay indicated minimal disruption in enzymatic activity. CONCLUSION: This method would allow for the selective incorporation of NMR-active isotopes into either of the VP1u domains, which can reduce signal overlap in NMR structural determination studies.
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Proteínas de la Cápside , Escherichia coli , Inteínas , Inteínas/genética , Proteínas de la Cápside/química , Proteínas de la Cápside/genética , Proteínas de la Cápside/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Dominios Proteicos , Parvovirus B19 Humano/genética , Parvovirus B19 Humano/química , Nostoc/genética , Nostoc/enzimología , Nostoc/química , Fosfolipasas A2/química , Fosfolipasas A2/genética , Fosfolipasas A2/metabolismo , Dicroismo Circular , HumanosRESUMEN
Structural biology efforts using cryogenic electron microscopy are frequently stifled by specimens adopting "preferred orientations" on grids, leading to anisotropic map resolution and impeding structure determination. Tilting the specimen stage during data collection is a generalizable solution but has historically led to substantial resolution attenuation. Here, we develop updated data collection and image processing workflows and demonstrate, using multiple specimens, that resolution attenuation is negligible or significantly reduced across tilt angles. Reconstructions with and without the stage tilted as high as 60° are virtually indistinguishable. These strategies allowed the reconstruction to 3 Å resolution of a bacterial RNA polymerase with preferred orientation, containing an unnatural nucleotide for studying novel base pair recognition. Furthermore, we present a quantitative framework that allows cryo-EM practitioners to define an optimal tilt angle during data acquisition. These results reinforce the utility of employing stage tilt for data collection and provide quantitative metrics to obtain isotropic maps.
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Benchmarking , Sistemas de Computación , Microscopía por Crioelectrón , Anisotropía , Recolección de DatosRESUMEN
The wavelength of a single frequency quantum dot distributed feedback (DFB) laser operating in the O-band is athermalised over a 74 °C ambient temperature range. Two techniques are presented, one utilising the laser self-heating for tuning control, the other using a resistive heater. Both techniques show greatly improved power efficiency over conventional wavelength control schemes, and both demonstrate wavelength stability of better than 0.1 nm (17.5 GHz) without mode hops over the entire temperature range. The use of a high operating temperature quantum dot laser together with an innovative submount design to increase the thermal impedance of the device enables the improved use of the laser self-heating for wavelength tuning. The submount design entails the laser being suspended over an air gap with the use of glass supports, preventing heat from escaping from the diode.
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Bocaparvovirus is an expansive genus of the Parvovirinae, with a wide range of vertebrate hosts. This study investigates Canine minute virus (CnMV), Rat bocavirus (RBoV), and Porcine bocavirus 1 (PBoV1). Both CnMV and PBoV1 have been found in gastrointestinal infections in their respective hosts, with CnMV responsible for spontaneous abortions in dogs, while PBoV has been associated with encephalomyelitis in piglets. The pathogenicity of the recently identified RBoV is currently unknown. To initiate the characterization of these viruses, their capsids structures were determined by cryo-electron microscopy at resolutions ranging from 2.3 to 2.7 Å. Compared to other parvoviruses, the CnMV, PBoV1, and RBoV capsids showed conserved features, such as the channel at the fivefold symmetry axis. However, major differences were observed at the two- and threefold axes. While CnMV displays prominent threefold protrusions, the same region is more recessed in PBoV1 and RBoV. Furthermore, the typical twofold axis depression of parvoviral capsids is absent in CnMV or very small in PBoV and RBoV. These capsid structures extend the structural portfolio for the Bocaparvovirus genus and will allow future characterization of these pathogens on a molecular level. This is important, as no antivirals or vaccines exist for these viruses.
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Bocavirus , Infecciones por Parvoviridae , Animales , Ratas , Porcinos , Perros , Microscopía por Crioelectrón , Proteínas de la Cápside/análisis , Cápside/química , Infecciones por Parvoviridae/veterinariaRESUMEN
Recombinant adeno-associated viruses (rAAVs) have emerged as one of the most promising gene therapy vectors that have been successfully used in pre-clinical models of heart disease. However, this has not translated well to humans due to species differences in rAAV transduction efficiency. As a result, the search for human cardiotropic capsids is a major contemporary challenge. We used a capsid-shuffled rAAV library to perform directed evolution in human iPSC-derived cardiomyocytes (hiPSC-CMs). Five candidates emerged, with four presenting high sequence identity to AAV6, while a fifth divergent variant was related to AAV3b. Functional analysis of the variants was performed in vitro using hiPSC-CMs, cardiac organoids, human cardiac slices, non-human primate and porcine cardiac slices, as well as mouse heart and liver in vivo. We showed that cell entry was not the best predictor of transgene expression efficiency. The novel variant rAAV.KK04 was the best-performing vector in human-based screening platforms, exceeding the benchmark rAAV6. None of the novel capsids demonstrate a significant transduction of liver in vivo. The range of experimental models used revealed the value of testing for tropism differences under the conditions of human specificity, bona fide, myocardium and cell type of interest.