Encyclopedia
Cross section through a Vesicular stomatitis Indiana virus virion. Vesiculovirus is a genus of ssRNA- viruses in the family Rhabdoviridae that infect mammals. These viruses are transmitted by insects (arbovirus) and rarely infect humans in which they cause flu-like disease that can lead to encephalitis.
ViralZone, SIB Swiss Institute of Bioinformatics
14 Mar 2024
Organization and expression of the polycistronic arterivirus equine arteritis virus (EAV) +RNA genome. (A) Top: EAV genome organization, showing the 5′-proximal replicase open reading frames (ORFs), as well as the downstream ORFs encoding the viral structural proteins envelope (E), membrane (M), nucleocapsid (N), and glycoproteins (GP) 2–5 and the 3′ poly(A) tail (An). Bottom: overview of the pp1a and pp1ab replicase polyproteins that result from genome translation, which requires an ORF1a/1b ribosomal frameshift (RFS) to produce pp1ab. Arrowheads represent sites cleaved by the three virus-encoded proteases (open for autoproteolytically processed ones, closed for sites processed by the main proteinase in nsp4). The resulting nonstructural proteins (nsp) are numbered. The key viral enzymatic domains such as the nsp1 papain-like cysteine proteinase β (PCP), nsp2 cysteine proteinase (CP), nsp4 serine proteinase (SP), nsp9 viral RNA-dependent RNA polymerase (RdRp), nsp10 helicase (Hel), and nsp11 endoribonuclease (Ne) are indicated. (B) Overview of viral mRNA species produced in EAV-infected cells. The ORFs expressed from the respective mRNAs are shown in gray, and the 5′ leader sequence is depicted in dark red. The orange boxes indicate the positions of transcription-regulating sequences (TRS). The gel hybridization image on the right is representative of the wild-type accumulation levels of the seven EAV mRNAs at the time point used for analysis in the study (see text for details). The amount of each mRNA, determined by quantitative phosphorimager analysis, is indicated as percentage of the total amount of viral mRNA. (C) Model for EAV replication and transcription. Continuous minus-strand RNA synthesis yields a genome-length minus strand template for genome replication, a process for which nsp1 is dispensable. Discontinuous minus-strand RNA synthesis results in a nested set of subgenome-length minus strands that serve as templates for sg mRNA synthesis (see text for details). Nsp1 is crucial for this process, which is also guided by a base pairing interaction between the TRS complement [(−)TRS] at the 3′ end of the nascent minus-strand and the genomic leader TRS, present in a RNA hairpin structure (LTH). [1]
Danny D. Nedialkova, Alexander E. Gorbalenya, Eric J. Snijder
25 Jan 2024
Malign lymphoma in the kidney of a cat, domestic shorthair. Note the hypoechoic area (arrow).
Kalumet, Wikimedia Commons
31 Jan 2024
Diodia vein chlorosis virus (DVCV) is an understudied whitefly-transmitted closterovirus [1].
iNaturalist
02 Feb 2024
Spherical viruses with icosahedral capsids. Bacillus virus phi29. [1]
Wikimedia Commons
07 Feb 2024
Zika virus particles (red) shown in African green monkey kidney cells.
NIAID, Wikimedia Commons
07 Feb 2024
Sympathetic innervation in vasculature. The sympathetic pathway is formed of two serially connected sets of neurons: preganglionic and postganglionic neurons. The preganglionic neurons originate in the brainstem or the spinal cord. They exit the spinal cord and synapse (using acetylcholine as a neurotransmitter) with postganglionic sympathetic neurons in the ganglia. The nerve endings of the postganglionic neurons branch repeatedly, forming synapses en passant (“synapses in passing”) or varicosities (knoblike swellings) containing mitochondria and synaptic vesicles. The key neurotransmitter in the synaptic vesicles of the varicosities is norepinephrine. In addition, the sympathetic preganglionic neurons synapse with chromaffin cells in the adrenal gland to stimulate the production of epinephrine and norepinephrine from the adrenal medulla. The produced epinephrine and norepinephrine then enter the blood and may affect distant blood vessels and tissues. Ach, acetylcholine; EPI, epinephrine; and NE, norepinephrine.
27 Feb 2024
Functional metal-polymer nanocomposites
Metal nanoparticles have a number of useful physical properties (e.g., surface plasmon resonance (SPR), fluorescence, superparamagnetism, ultra high/low refractive index, etc.). Owing to the very small size (diameter of only few nanometer tents), nanoparticles dispersed in optical media do not scatter the visible light. Consequently, nanoparticles embedding in optical plastics (e.g., amorphous polystyrene, poly(methyl methacrylate), polycarbonate, etc.) leads to transparent polymeric nanocomposites with very useful functional properties, that can be used in different technological applications like for example fluorescent optical media, optical limiters (e.g., color filters based on SPR), magneto-optical plastics, ultra high/low refractive index plastic materials, etc.
01 Apr 2024
Photo of cucumber mosaic symptoms on cucumber fruit.
Wikimedia Commons, William M. Brown Jr.
01 Apr 2024
Picornavirus genome, proteins, and capsid organization. (A) Representation of the picornavirus genome, the VPg, and the polyA tail, showing the single ORF location. The position of the P1–3 regions, the flanking 5′ and 3′UTR, and the IRES are indicated. (B) A bar diagram showing the polyprotein (gray box) and the proteolytic cascade that leads to all picornaviral proteins (colored boxes). Boxes include the protein names following the genome-ORF regions' nomenclature (number–letters) or the VP1–4 nomenclature for the structural proteins. Colored rhombi indicate cleavage points and are labeled with the corresponding protease name. (C) Overall view of the canonical picornavirus protomer with the proteins VP1 (blue), VP2 (green), VP3 (red), and VP4 (yellow). The protein N- and C-termini are indicated as encircled N and C letters, and yellow circles show the 5-,−3, 2-fold symmetry axes positions. Lipid components as the VP4 myristoylation and the “pocket factor” are depicted as black spheres. The “canyon” region is shown as a gray circular segment shadow. (D) Schematics of the “jelly roll” fold of VP1–3 proteins inscribed in a trapezoidal prism where the yellow highlighted face corresponds to the external capsid surface, and the dark gray base faces the inner capsid. The secondary structure elements are colored from N- to C-terminus according to the color code bar below. External loops and N- and C-terminus are indicated. (E) Overall view of the picornavirus capsid showing the outer surface of VP1 (blue), VP2 (green), and VP3 (red). The yellow dotted line indicates the boundaries of one pentamer. The solid yellow line marks the icosahedral asymmetric subunit and thinner lines separate proteins following the trapezoidal schematics shown in (D). Symmetry 5-, 3-, 2-fold symmetry axes are indicated in yellow circles.
Wikimedia Commons, Javier Orlando Cifuente and Gonzalo Moratorio
24 Jan 2024
Schematic drawing of a Cystovirus virion (cross section and side view). Enveloped, spherical virion of 85 nm in diameter. The virion has a double capsid structure: the outer capsid has a T=13 laevo icosahedral symmetry and the inner capsid has a T=2* icosahedral symmetry.
ViralZone, SIB Swiss Institute of Bioinformatics, Wikimedia Commons
22 Feb 2024
A beautiful morphology leads to a technologically useful nanomaterial. Metal-polymer nanocomposites with the best functional properties (for example, the most intense and well-defined optical properties) always are observed in the case of filling with a very uniform nanoparticle system (i.e., monodispersed particles with a regular geometry) [1]. Usually, poor nanoparticle samples (i.e., polydispersed and/or non regularly shaped nanoparticles) lead to nanomaterials with very low-quality nanoscopic properties. Since highly uniform nanoparticle systems (i.e., monodispersed particles with regular geometry) have also an astonishing morphology (beauty implies shape harmony/uniformity) and, in addition, good physical properties result also technologically useful, it is possible to say that: 'a useful nanomaterial always has a beautiful microscopic structure'. Property and structure are strictly related in nanomaterials. To understand how much important is the dependence of properties from structure on the nanoscale, it needs to be considered the analogy between atomic clusters (and/or small nanoparticles) and the organic molecules of a homologous class (e.g., alkanes). As well known, physical/chemical properties change significantly moving along the homologous classes of organic chemistry and therefore the same behaviour have to occur for the atomic clusters with changing of nuclearity. Owing to such strict properties-structure connection, scattering in the size/shape implies a dispersion of the property values. Consequently, particles with polydispersed size/shape always show poor properties at nanoscale and therefore they result technologically unuseful.
18 Mar 2024
Comparison of the size of Megaklothovirus to other giant viruses, a common virus (HIV) and bacteria (E. coli). [1]
Wikimedia Commons, Domi751
02 Apr 2024
Magnified 1500X, this scanning electron micrograph (SEM) revealed some of the minute exoskeletal details found at the proboscis tip of an unidentified mosquito found deceased in the suburbs of Decatur, Georgia. The proboscis is the organ used by this, as well as other like insects, to feed upon the blood of a warm-blooded host, including human beings. What you see here, is the sheath that encases a pair of needle-sharp "stylets", which together are known as the "fascicle". The larger of the two stylets, known as the "labrum", when viewed in cross-section, takes on the shape of a "V", and acts as a gutter, directing the ingested host blood towards the insect's mouth. The hair-like structures are known as "setae", and are really extensions of the insect's exoskeletal, chitinous covering. These setae act as sensory organs, transmitting impulses indicating changes in the organism's environment.
Public Health Image Library, Elizabeth Perez
24 Jan 2024
Upon entry into the host cell nucleus, (i) the vRNP-associated viral polymerase transcribes the viral mRNAs. (ii) The mRNAs are either directly, or after alternative splicing, exported for translation by cytosolic ribosomes. (iii) Newly synthesized viral polymerase subunits (PA, PB1, and PB2) and nucleoprotein (NP) are imported back into the nucleus. (iv) Due to the inefficient dinucleotide priming, the vRNP-associated viral polymerase also infrequently transcribes complimentary RNA (cRNA) copies that assemble into cRNPs via (v) binding of a newly synthesized viral polymerase (PA, PB1, and PB2) and NP. (vi) The polymerase transcribes viral RNA (vRNA) copies from the positive strand in the cRNPs and these assemble into vRNPs by (vii) association with a new viral polymerase (PA, PB1, and PB2) and NP. Once assembled, the new vRNPs can (viii) transcribe additional viral mRNAs, (ix) transcribe new cRNA copies, or (x) associate with the newly synthesized viral proteins M1 and NS2 to facilitate the recruitment of CRM1, which (xi) mediates the nuclear export of the vRNP. (xiia) Once exported, the vRNPs then associate with Rab11 that assists in the trafficking of the vRNPs toward the cell surface. The vRNP trafficking either occurs by Rab11-containing vesicles associated with microtubules or (xiib) through Rab11 located in the modified endoplasmic reticulum (ER) membranes. How the vRNPs reach the budding site at the plasma membrane is currently not known.[1]
Wikimedia Commons, Dan Dou, Rebecca Revol, Henrik Östbye, Hao Wang, and Robert Daniels
01 Feb 2024
This negatively-stained transmission electron microscopic (TEM) image revealed the presence of a number of Hong Kong flu virus virions, the H3N2 subtype of the Influenza A virus. Note the proteinaceous coat, or capsid, surrounding each virion, and the hemagglutinin-neuraminidase spikes, which differ in terms of their molecular make-up from strain to strain.
Wikimedia Commons, CDC/Fred Murphy
01 Feb 2024
Electron microscopy images of thin sections and partially purified virions from cells infected with coronavirus. Electron microscopy images of concentrated Transmissible gastroenteritis coronavirus (TGEV). [1]
Cristina Riquelme, David Escors, Javier Ortego, Carlos M. Sanchez, Branislava Uzelac-Keserovic, Konstantin Apostolov, and Luis Enjuanes, Wikimedia Commons
07 Feb 2024
This image depicts adenovirus. Computer graphics are made by utilizing data fed into a computer. This data may consist of chemical weights and measures and the structure of specific elements. A three-dimensional image can be made so one can visualize an otherwise minute structure.
Richard Feldmann, National Cancer Institute, Wikimedia Commons
07 Feb 2024
Spices show great potential as substitutes for artificial food preservatives.
09 Nov 2023
Comparison of ORFs and protein domains across nidovirus groups, illustrating the genome architecture of arteriviruses (equine arteritis virus), mesoniviruses (Nam Dinh virus), coronaviruses (SARS-CoV), and planarian secretory cell nidovirus (PSCNV), the nidovirus with the largest known genome size at 41.1kb. Novel domains present in PSCNV are included.
ORFs and encoded protein domains in genomes of viruses representing three nidovirus families and PSCNV. The protein-encoding part of the genomes is split in three adjacent regions, which are colored and labelled accordingly. EAV, equine arteritis virus; NDiV, Nam Dinh virus; SARS-CoV (see S1 Table for details on these viruses). ORF1a frame is set as zero. Protein domains conserved between these nidoviruses and PSCNV, and those specific to PSCNV are shown. TM, transmembrane domain (TM helices are shown by black bars above TM domains); Tandem repeats, two adjacent homologous regions of unknown function; RNase T2, ribonuclease T2 homolog; 3CLpro, 3C-like protease; NiRAN, nidovirus RdRp-associated nucleotidyltransferase; RdRp, RNA-dependent RNA polymerase; HEL1, superfamily 1 helicase with upstream Zn-binding domain (ZBD); ExoN, DEDDh subfamily exoribonuclease; N-MT and O-MT, SAM-dependent N7- and 2’-O-methyltransferases, respectively; Thr-rich, region enriched with Thr residue; FN2a/b, fibronectin type 2 domains; ANK, ankyrin domain. [1]
Amir Saberi, Anastasia A. Gulyaeva, John L. Brubacher, Phillip A. Newmark, Alexander E. Gorbalenya
01 Feb 2024
