Browsing by Subject "parechovirus"

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  • Domanska, Ausra; Guryanov, Sergey; Butcher, Sarah J. (2021)
    Parechoviruses belong to the genus Parechovirus within the family Picornaviridae and are non-enveloped icosahedral viruses with a single-stranded RNA genome. Parechoviruses include human and animal pathogens classified into six species. Those that infect humans belong to the Parechovirus A species and can cause infections ranging from mild gastrointestinal or respiratory illness to severe neonatal sepsis. There are no approved antivirals available to treat parechovirus (nor any other picornavirus) infections. In this parechovirus review, we focus on the cleaved protein products resulting from the polyprotein processing after translation comparing and contrasting their known or predicted structures and functions to those of other picornaviruses. The review also includes our original analysis from sequence and structure prediction. This review highlights significant structural differences between parechoviral and other picornaviral proteins, suggesting that parechovirus drug development should specifically be directed to parechoviral targets.
  • Hayes, A.; Nguyen, D.; Andersson, M.; Anton, A.; Bailly, J-L; Beard, S.; Benschop, K. S. M.; Berginc, N.; Blomqvist, S.; Cunningham, E.; Davis, D.; Dembinski, J. L.; Diedrich, S.; Dudman, S. G.; Dyrdak, R.; Eltringham, G. J. A.; Gonzales-Goggia, S.; Gunson, R.; Howson-Wells, H. C.; Jääskeläinen, A. J.; Lopez-Labrador, F. X.; Maier, M.; Majumdar, M.; Midgley, S.; Mirand, A.; Morley, U.; Nordbo, S. A.; Oikarinen, S.; Osman, H.; Papa, A.; Pellegrinelli, L.; Piralla, A.; Rabella, N.; Richter, J.; Smith, M.; Strand, A. Söderlund; Templeton, K.; Vipond, B.; Vuorinen, T.; Williams, C.; Wollants, E.; Zakikhany, K.; Fischer, T. K.; Harvala, H.; Simmonds, P. (2020)
    Polymerase chain reaction (PCR) detection has become the gold standard for diagnosis and typing of enterovirus (EV) and human parechovirus (HPeV) infections. Its effectiveness depends critically on using the appropriate sample types and high assay sensitivity as viral loads in cerebrospinal fluid samples from meningitis and sepsis clinical presentation can be extremely low. This study evaluated the sensitivity and specificity of currently used commercial and in-house diagnostic and typing assays. Accurately quantified RNA transcript controls were distributed to 27 diagnostic and 12 reference laboratories in 17 European countries for blinded testing. Transcripts represented the four human EV species (EV-A71, echovirus 30, coxsackie A virus 21, and EV-D68), HPeV3, and specificity controls. Reported results from 48 in-house and 15 commercial assays showed 98% detection frequencies of high copy (1000 RNA copies/5 mu L) transcripts. In-house assays showed significantly greater detection frequencies of the low copy (10 copies/5 mu L) EV and HPeV transcripts (81% and 86%, respectively) compared with commercial assays (56%, 50%; P = 7 x 10(-5)). EV-specific PCRs showed low cross-reactivity with human rhinovirus C (3 of 42 tests) and infrequent positivity in the negative control (2 of 63 tests). Most or all high copy EV and HPeV controls were successfully typed (88%, 100%) by reference laboratories, but showed reduced effectiveness for low copy controls (41%, 67%). Stabilized RNA transcripts provide an effective, logistically simple and inexpensive reagent for evaluation of diagnostic assay performance. The study provides reassurance of the performance of the many in-house assay formats used across Europe. However, it identified often substantially reduced sensitivities of commercial assays often used as point-of-care tests.
  • Plavec, Zlatka (Helsingin yliopisto, 2019)
    OBJECTIVES and RESEARCH QUESTION. Human parechovirus 3 (HPeV3) is a (+)ssRNA icosahaedrally symmetric virus which causes meningoencephalitis and sepsis in children and neonates. As it causes the most severe symptoms among parechoviruses it is attracting more attention (4). Currently there are no approved broad treatment strategies against parechoviruses, however recent research by Rhoden et al., 2017, reported the antiviral activity of posaconazole (PSZ) against HPeV3 in cell culture. Posaconazole is an antifungal drug approved for use against Candida and Aspergillus infections. It targets lanosterol-14alpha-demethylase and prevents the production of ergosterol, a lipid vital for fungal membranes not present in mammalian cells (24). In mammalian cells PSZ accumulates at the endoplasmic reticulum (ER) and binds to the oxysterol-binding protein (OSBP) and Niemann-pick type C1 (NPC1) (59, 28, 30). The drug may affect cellular components and thusly block parechoviral infection or could bind to the viral capsid. METHODS. To test viral capsid-binding hypothesis PSZ activity was tested in a range of concentrations against two HPeV3 isolates and HPeV1 Harris in Vero and HT29 cell lines. HPeV3 isolate 152037 was purified on a CsCl step gradient and imaged by cryo electron microscopy (cryo-EM). Single particle analysis was done in Scipion (40) and acquired density maps visualized in UCSF Chimera (49). Atomic model of a different isolate of HPeV3 (PDB ID: 6GV4, 16) was changed at 6 sites and fitted to density maps from this work in Coot (52). Maps were subtracted in search of density that would represent PSZ. RESULTS. PSZ was effective against both HPeV3 isolates at 1 μM in Vero cells when added to the virus prior to infection, however not in HT29 cells. At higher concentrations (>10 μM) PSZ formed crystals which limited the concentration that can be used for cryo-EM. In order to test the hypothesis of PSZ being a capsid binder 3 datasets were collected, HPeV3 control, HPeV3+DMSO and HPeV3+PSZ (4 μM) with final resolutions after single particle analysis of 3.3 Å, 3.9 Å and 3.4 Å respectively. Subtraction of maps yielded no difference that would represent PSZ. DISCUSSION and CONCLUSION. PSZ does not appear to be a capsid binder although it appears to work early in the infection. Absence of PSZ density in HPeV3+PSZ density map could be due to low saturation and images containing PSZ were filtered out in image processing. Another possibility is low affinity of PSZ for the capsid. As PSZ binds various membranes it is possible that it blocks HPeV3 infection by targeting cell components. Additional experiments could be performed in the future in order to provide insight into which stages of infection PSZ affects.