Evidence of efficient transovarial transmission of culex flavivirus by Culex pipiens (Diptera: Culicidae)

Rungrat Saiyasombat, Bethany G. Bolling, Aaron Brault, Lyric C. Bartholomay, Bradley J. Blitvich

Research output: Contribution to journalArticle

60 Scopus citations

Abstract

This study determined the transovarial transmission (TOT) potential and tissue tropisms of Culex flavivirus (CxFV), an insect-specific flavivirus, in Culex pipiens (L.). Several hundred mosquito egg rafts were collected in the field, transferred to the insectaries, reared to the fourth larval instar, and identified using morphological characteristics. Cx. pipiens were reared to adults, allowed to oviposit in individual containers, and tested for CxFV RNA by reverse transcription-polymerase chain reaction (RT-PCR) and nucleotide sequencing. Eighteen CxFV RNA-positive females were identified from 26 females that oviposited viable egg rafts. Thirty F1 adults from each positive female were individually tested by RT-PCR for CxFV RNA. Viral RNA was detected in 526 of 540 progeny, and thus, the filial infection rate was 97.4%. Because all 18 positive females produced infected offspring, the TOT prevalence was 100%. These data indicated that efficient TOT of CxFV occurs in nature. To define the tissue tropisms of CxFV, different tissues (salivary glands, ovaries, testes, head, fat bodies, and midguts) were removed from the remainder of the F 1 and tested by RT-PCR for CxFV RNA. Viral RNA was detected in all tissues. Additionally, uninfected laboratory-colonized Cx. pipiens were infected with CxFV by needle inoculation, and ovaries were collected at 4, 6, 8, and 12 d postinoculation and tested for CxFV RNA by RT-PCR. Viral RNA was detected at all time points, demonstrating that CxFV infects the ovaries as early as 4 d postinoculation. Surprisingly, however, we were unable to demonstrate transovarial transmission despite the presence of viral RNA in the ovaries. Nevertheless, the experiments performed with field-infected Cx. pipiens demonstrate that TOT is an efficient mechanism by which CxFV is maintained in mosquitoes in nature.

Original languageEnglish (US)
Pages (from-to)1031-1038
Number of pages8
JournalJournal of Medical Entomology
Volume48
Issue number5
DOIs
StatePublished - Sep 1 2011
Externally publishedYes

Keywords

  • Culex flavivirus
  • Culex pipiens
  • flavivirus
  • tissue tropisms
  • transovarial transmission

ASJC Scopus subject areas

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

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