Attenuation of pathogenic Rift Valley fever virus strain through the chimeric S-segment encoding sandfly fever phlebovirus NSs or a dominant-negative PKR

Shoko Nishiyama, Olga A.L. Slack, Nandadeva Lokugamage, Terence E. Hill, Terry L. Juelich, Lihong Zhang, Jennifer K. Smith, David Perez, Bin Gong, Alexander N. Freiberg, Tetsuro Ikegami

Research output: Contribution to journalComment/debate

11 Scopus citations

Abstract

Rift Valley fever is a mosquito-borne zoonotic disease affecting ruminants and humans. Rift Valley fever virus (RVFV: family Bunyaviridae, genus Phlebovirus) causes abortions and fetal malformations in ruminants, and hemorrhagic fever, encephalitis, or retinitis in humans. The live-attenuated MP-12 vaccine is conditionally licensed for veterinary use in the US. However, this vaccine lacks a marker for the differentiation of vaccinated from infected animals (DIVA). NSs gene is dispensable for RVFV replication, and thus, rMP-12 strains lacking NSs gene is applicable to monitor vaccinated animals. However, the immunogenicity of MP-12 lacking NSs was not as high as parental MP-12. Thus, chimeric MP-12 strains encoding NSs from either Toscana virus (TOSV), sandfly fever Sicilian virus (SFSV) or Punta Toro virus Adames strain (PTA) were characterized previously. Although chimeric MP-12 strains are highly immunogenic, the attenuation through the S-segment remains unknown. Using pathogenic ZH501 strain, we aimed to demonstrate the attenuation of ZH501 strain through chimeric S-segment encoding either the NSs of TOSV, SFSV, PTA, or Punta Toro virus Balliet strain (PTB). In addition, we characterized rZH501 encoding a human dominant-negative PKR (PKRΔE7), which also enhances the immunogenicity of MP-12. Study done on mice revealed that attenuation of rZH501 occurred through the S-segment encoding either PKRΔE7 or SFSV NSs. However, rZH501 encoding either TOSV, PTA, or PTB NSs in the S-segment uniformly caused lethal encephalitis. Our results indicated that the S-segments encoding PKRΔE7 or SFSV NSs are attenuated and thus applicable toward next generation MP-12 vaccine candidates that encode a DIVA marker.

Original languageEnglish (US)
Pages (from-to)871-881
Number of pages11
JournalVirulence
Volume7
Issue number8
DOIs
StatePublished - Nov 16 2016

Keywords

  • NSs
  • PKR
  • Rift valley fever virus
  • Toscana virus
  • attenuation
  • phlebovirus
  • punta toro virus
  • sandfly fever Sicilian virus
  • vaccine

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Microbiology (medical)
  • Infectious Diseases

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