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Cell culture and new technologies for in-vitro propagation of HEV virus

Cell culture and new technologies for in-vitro propagation of HEV virus. Alessandra Berto PhD student Pulawy 14/4/2101. HEV. Is the sole member of the family Hepeviridae Is a non enveloped, spherical particle, single stranded and positive-sense RNA.

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Cell culture and new technologies for in-vitro propagation of HEV virus

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  1. Cell culture and new technologies for in-vitro propagation of HEV virus Alessandra Berto PhD student Pulawy 14/4/2101

  2. HEV • Is the sole member of the family Hepeviridae • Is a non enveloped, spherical particle, single stranded and positive-sense RNA • Contains three open reading frames (ORF) • The disease is that of an acute, icteric hepatitis. The incubation period ranges from 2 to 9 wk. • Animals can be infected with the virus • Classified into 4 genotypes

  3. Transmission of HEV • In developing regions is largely waterborne due to inadequate separation of human sewage from drinking water supplies • In developed regions transmission routes are not clear, but pig appear to play a central role as a reservoir of infection

  4. Vocational exposure: vets, farmer processing and retail staff Sika deer pig man Human sewage, floods faeces Abattoir effluent Ingestion of undercooked sika deer meat slurry pasture watercourses Ingestion of undercooked pig meat, liver Water based-reaction corps Abstraction for drinking water Crops via irrigation molluscs Blood transfusion Other mammals man

  5. The exact transmission routes are unclear, largely because HEV is extremely difficult to propagate in vitro, but retail pig products have been shown to contain HEV RNA.

  6. General background • Tanaka et al (Tanaka et al., 2007)have tested 21 cell lines including PLC/PRF/5 cells using a faecal suspension with high HEV load as inoculum (Huang et al., 1992, Huang et al., 1995, Huang et al., 1999, Li, 1996). A high load of HEV was detected in the culture supernatant of cultivated PLC/PRF/5 cells from day 12 post inoculation. • At VLA Weybridge laboratory, several attempts were made to reproduce Tanaka’s work using field swine HEV PCR positive faecal materials as inoculum, but without success.

  7. The lack of an efficient and reliable cell culture system and a practical animal model for HEV have hindered studies on mechanisms of HEV replication, transmission, pathogenesis and environmental survival.

  8. There are several reports in the literature demonstrating the potential of a new 3D culture system, Rotating Wall Vessel (RWV), for the growth of fastidious viruses as well as bacteria (Kageyama et al., 2003, Takahashi et al., 2007, Lorenzo et al., 2008, Goodwin et al., 1993). • This 3D culture system has been used to grow fastidious Noroviruses from faecal materials (Kageyama et al., 2003).The system offers a potential for in vitro cultivation of HEV.

  9. Aim 1 • To evaluate the new 3D culture system to assess HEV infectivity. This is to verify if the HEV virus content detected by PCR in pig and environmental samples is infectious. • To test the progeny’s infectivity • To compare the efficiency of the 3D system to the conventional 2D system. In addition, cells grown in the 3D system were transferred to a 2D system and infected. This aims to produce the best tool with which to examine large numbers of samples and thereby investigate potential transmission routes.

  10. Results • HEV RNA was detected from 15 dpi in the 3D culture infected with inoculum HEV positive liver sample obtained from an experimentally infected pig • Two distinct peaks are observed, the first between 24 and 42 dpi and between 30 and 42, and the second between 62 and 175 dpi for both

  11. 3 systems developing 3D transferred in 2D 3D 2D

  12. Ct values show a reducing trend in the undiluted and 10^-2 dilution of inoculum in the period of 40 days • The Ct values for the 10^-1 dilution of inoculum remained unchanged till 30 dpi

  13. A similar trend was observed for the 3D cells transferred to 2D for the neat inoculum.

  14. The Ct values for neat inoculum remained unchanged

  15. Discussion The results have shown detectable Ct values in quantitative RT-PCR at all dpi. In the parallel 2D system Ct values were not detectable at any dpi. The observation of viral replication in PLC/PRF/5 cells in this system indicates that the 3D system may potentially be used as a tool to elucidate the pathobiology of HEV, which may, in turn, facilitate vaccine research, monitoring of HEV contamination and HEV survival through processing to point of sale.

  16. In experiment 2, a small titration range was introduced to give some impression of the relative sensitivity of 3D, 3D transferred to 2D and 2D alone. The virus was detectable by real time RT- PCR in all three systems until the end of the experiment. • This data also demonstrates that importantly, the virus progeny obtained during experiment 1 was infectious.

  17. Aim 2 construction and use of an interferon knockout cell line to further enhance the sensitivity of the system to detect viable virus.

  18. PROCEDURE • AMPLIFICATION OF THE PLASMIDS 3 plasmids pdl’PIV5-V: Expression is controlled by the constitutive SFFV promoter, which produces a single bicistonic mRNA that encodes for the PIV5-V together with an eukaryotic resistance marker, puromycin, for mammalian cell selection. pCMV R8.91: Plasmid expressing the gag/pol, tat and rev genes of HIV-1. pMD-G: Plasmid expressing the vesicular stomatitis virus glycoprotein (VSV-G) gene The plasmids will be amplified in E. coli

  19. 2) TRANSFECTION OF 293 T CELLS to create the virion containing the proteins encoded the plasmids, these need to be transfect in highly permissive cell line 3)TRANSDUCTION OF PLC/PRF5 supernatant collected form the 293T cells was transferred in PLC/PRF/5 cells and subsequentely selected with puromycin

  20. Result • The experiment is failed. Probably explanation: - the DNA inside the 3 plasmids was degraded - PLC/PRF/5 are not permissive to the lentivirus - too much puromycin was added at the last one - step

  21. Before the repeat experiment PLC/PRF/5 were tested for IFN production through CAT ELISA test RESULT: Not infected cells tested for INF production HEV positive cells result No IFN activity

  22. Aim 3 Confocal microscope analysis to compare 3D and 2D cells morphology to proof the major differentiation of 3D cells

  23. 2D CD81 3D CD81

  24. 2D B-Catenin 3D B-Catenin

  25. 2D E-Caderin 3D E-Caderin

  26. Aim4 to infect cells with not heated liver, liver heated at 56oC for 1 hour and at 100oC for 15 minutes and detect at which temperature the virus is inactivated

  27. negative positive Feagins et al., 2008

  28. The experiment is still ongoing………..

  29. Future Plans • Other virus inactivation strategy are in view; such as inactivate the virus with UV, high pressure system, detergent like decon or ETOH • Samples analysis • EM analysis

  30. It will be tried to implement 3D cell culture for HEV Gt4 propagation in Lelystad. If this works Gt4 inactivation experiments can be performed • HEV Gt4 experimental infections in Wild boar and mice • Establishment of HEV Gt3 and GT4 infectious dose in mice

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