Simulated overwintering of encephalitis viruses in diapausing female Culex tarsalis (Diptera

Culicidae)

William Reisen, Laura D. Kramer, Robert E. Chiles, Teresa M. Wolfe, Emily Gene N. Green

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Female Culex tarsalis Coquillett in reproductive diapause were infected per os or by intrathoracic inoculation with western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLJE) viruses during "fall," maintained over a simulated "winter," and then tested for virus infection and transmission in vitro and in vivo after "vernal" termination. Exposure of F1 progeny of field-collected females to cool temperatures and short daylength produced females in reproductive diapause that were reluctant to imbibe infectious virus from pledgets soaked with suspensions of virus, blood and sucrose (2.5% by volume). Those infected per os maintained virus at very low or undetectable titers. Some females that originally tested negative for WEE by plaque assay on Vero cell culture tested positive by reverse transcriptase-polymerase chain reaction (RT-PCR) and by Vero cell culture after passage in mosquito cells. Few females became infected orally with SLE. but these infected females developed elevated titers. Females inoculated with SLE retained their infection through winter and then transmitted readily in vitro and in vivo. Feeding on a vertebrate host after diapause termination significantly increased the titer of SLE in previously infected females. These experiments simulated how infections acquired either horizontally or vertically may provide mechanisms for WEE and SLE overwintering. Attempts to detect infected females during winter following a summer with enzootic WEE activity were negative by both RT-PCR and plaque assay.

Original languageEnglish (US)
Pages (from-to)226-233
Number of pages8
JournalJournal of Medical Entomology
Volume39
Issue number1
DOIs
StatePublished - Jan 1 2002

Fingerprint

Encephalitis Viruses
Culex tarsalis
Culex
encephalitis
Culicidae
Diptera
overwintering
Western Equine Encephalomyelitis
Western equine encephalomyelitis
viruses
diapause
Vero Cells
Viruses
Reverse Transcriptase Polymerase Chain Reaction
winter
cell culture
St. Louis Encephalitis Viruses
Cell Culture Techniques
reverse transcriptase polymerase chain reaction
Saint Louis encephalitis virus

Keywords

  • Arbovirus
  • Culex tarsalis
  • Diapause
  • St. Louis encephalitis virus
  • Western equine encephalomyelitis virus

ASJC Scopus subject areas

  • Parasitology
  • veterinary(all)
  • Insect Science
  • Infectious Diseases

Cite this

Simulated overwintering of encephalitis viruses in diapausing female Culex tarsalis (Diptera : Culicidae). / Reisen, William; Kramer, Laura D.; Chiles, Robert E.; Wolfe, Teresa M.; Green, Emily Gene N.

In: Journal of Medical Entomology, Vol. 39, No. 1, 01.01.2002, p. 226-233.

Research output: Contribution to journalArticle

Reisen, William ; Kramer, Laura D. ; Chiles, Robert E. ; Wolfe, Teresa M. ; Green, Emily Gene N. / Simulated overwintering of encephalitis viruses in diapausing female Culex tarsalis (Diptera : Culicidae). In: Journal of Medical Entomology. 2002 ; Vol. 39, No. 1. pp. 226-233.
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