Effects of virus dose and extrinsic incubation temperature on vector competence of culex nigripalpus (diptera: Culicidae) for st. Louis encephalitis virus

Stephanie L. Richards, Sheri L. Anderson, Cynthia C. Lord, Walter J. Tabachnick

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Culex nigripalpus Theobald is a primary vector of St. Louis encephalitis virus in the southeastern United States. Cx. nigripalpus females were fed blood containing a low (4.0 ± 0.01 log10 plaque-forming unit equivalents (PFUeq) /ml) or high (4.7 ± 0.1 log10 PFUeq/ml) St. Louis encephalitis virus dose and maintained at extrinsic incubation temperatures (EIT) of 25 or 28°C for 12 d. Vector competence was measured via quantitative real-time reverse transcriptase polymerase chain reaction to estimate PFUeq using rates of infection, dissemination, and transmission. There were no differences in infection rates between the two EITs at either dose. The low dose had higher infection rates at both EITs. Dissemination rates were significantly higher at 28°C compared with 25°C at both doses. Virus transmission was observed (<7%) only at 28°C for both doses. The virus titer in body tissues was greater at 28°C compared with 25°C at both doses. The difference between the EITs was greater at the low dose, resulting in a higher titer for the low dose than the high dose at 28°C. Virus titers in leg tissues were greater in mosquitoes fed the high versus low dose, but were not influenced by EIT. Further investigations using a variety of environmental and biological factors would be useful in exploring the complexity of vector competence.

Original languageEnglish
Pages (from-to)1502-1506
Number of pages5
JournalJournal of Medical Entomology
Volume49
Issue number6
DOIs
StatePublished - Nov 2012
Externally publishedYes

Keywords

  • Culex nigripalpus
  • St. Louis encephalitis virus
  • vector competence

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