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Transmission of West Nile virus by Culex quinquefasciatus say infected with Culex Flavivirus Izabal.

Kent RJ, Crabtree MB, Miller BR - PLoS Negl Trop Dis (2010)

Bottom Line: There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05).However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014).Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva.

View Article: PubMed Central - PubMed

Affiliation: Division of Vector-Borne Infectious Diseases, Arbovirus Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA. fxk7@cdc.gov

ABSTRACT

Background: The natural history and potential impact of mosquito-specific flaviviruses on the transmission efficiency of West Nile virus (WNV) is unknown. The objective of this study was to determine whether or not prior infection with Culex flavivirus (CxFV) Izabal altered the vector competence of Cx. quinquefasciatus Say for transmission of a co-circulating strain of West Nile virus (WNV) from Guatemala.

Methods and findings: CxFV-negative Culex quinquefasciatus and those infected with CxFV Izabal by intrathoracic inoculation were administered WNV-infectious blood meals. Infection, dissemination, and transmission of WNV were measured by plaque titration on Vero cells of individual mosquito bodies, legs, or saliva, respectively, two weeks following WNV exposure. Additional groups of Cx. quinquefasciatus were intrathoracically inoculated with WNV alone or WNV+CxFV Izabal simultaneously, and saliva collected nine days post inoculation. Growth of WNV in Aedes albopictus C6/36 cells or Cx. quinquefasciatus was not inhibited by prior infection with CxFV Izabal. There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05). However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014). Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva.

Conclusions: In the sequential infection experiments, prior infection with CxFV Izabal had no significant impact on WNV replication, infection, dissemination, or transmission by Cx. quinquefasciatus, however WNV transmission was enhanced in the Honduras colony when mosquitoes were inoculated simultaneously with both viruses.

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Replication of WNV in CxFV Izabal (+) and CxFV Izabal (−) C6/36 cells.CxFV (+) cells were infected two days prior to re-infection with WNV.
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pntd-0000671-g004: Replication of WNV in CxFV Izabal (+) and CxFV Izabal (−) C6/36 cells.CxFV (+) cells were infected two days prior to re-infection with WNV.

Mentions: Replication kinetics of CxFV Izabal were determined in C6/36 cells and in Cx. quinquefasciatus Sebring strain mosquitoes (Figs. 2,3). Replication of WNV was also monitored in CxFV Izabal (+) and (−) C6/36 cells, and in CxFV Izabal (+) and (−) Cx. quinquefasciatus Sebring (Figs. 4,5). In C6/36 cells, CxFV Izabal (passage 1) reached a maximum titer of approximately 7.0 log10 plaque forming units (pfu)/mL six days following infection at either multiplicity of infection (MOI) of 0.03 or MOI = 0.1, approximately one log less than that observed for KRV (Fig. 2). CxFV Izabal caused evident cytopathic effects (CPE) in C6/36 cells, completely destroying the cell monolayer by 8 days post infection (DPI) following inoculation at an MOI of 0.1. In Cx. quinquefasciatus Sebring mosquitoes exposed to CxFV Izabal by intrathoracic inoculation, CxFV Izabal reached a peak titer of 4.3 log10 pfu/mosquito approximately 8 DPI. Mosquitoes were not susceptible to CxFV Izabal infection following oral exposure (Fig. 3).


Transmission of West Nile virus by Culex quinquefasciatus say infected with Culex Flavivirus Izabal.

Kent RJ, Crabtree MB, Miller BR - PLoS Negl Trop Dis (2010)

Replication of WNV in CxFV Izabal (+) and CxFV Izabal (−) C6/36 cells.CxFV (+) cells were infected two days prior to re-infection with WNV.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2864301&req=5

pntd-0000671-g004: Replication of WNV in CxFV Izabal (+) and CxFV Izabal (−) C6/36 cells.CxFV (+) cells were infected two days prior to re-infection with WNV.
Mentions: Replication kinetics of CxFV Izabal were determined in C6/36 cells and in Cx. quinquefasciatus Sebring strain mosquitoes (Figs. 2,3). Replication of WNV was also monitored in CxFV Izabal (+) and (−) C6/36 cells, and in CxFV Izabal (+) and (−) Cx. quinquefasciatus Sebring (Figs. 4,5). In C6/36 cells, CxFV Izabal (passage 1) reached a maximum titer of approximately 7.0 log10 plaque forming units (pfu)/mL six days following infection at either multiplicity of infection (MOI) of 0.03 or MOI = 0.1, approximately one log less than that observed for KRV (Fig. 2). CxFV Izabal caused evident cytopathic effects (CPE) in C6/36 cells, completely destroying the cell monolayer by 8 days post infection (DPI) following inoculation at an MOI of 0.1. In Cx. quinquefasciatus Sebring mosquitoes exposed to CxFV Izabal by intrathoracic inoculation, CxFV Izabal reached a peak titer of 4.3 log10 pfu/mosquito approximately 8 DPI. Mosquitoes were not susceptible to CxFV Izabal infection following oral exposure (Fig. 3).

Bottom Line: There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05).However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014).Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva.

View Article: PubMed Central - PubMed

Affiliation: Division of Vector-Borne Infectious Diseases, Arbovirus Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA. fxk7@cdc.gov

ABSTRACT

Background: The natural history and potential impact of mosquito-specific flaviviruses on the transmission efficiency of West Nile virus (WNV) is unknown. The objective of this study was to determine whether or not prior infection with Culex flavivirus (CxFV) Izabal altered the vector competence of Cx. quinquefasciatus Say for transmission of a co-circulating strain of West Nile virus (WNV) from Guatemala.

Methods and findings: CxFV-negative Culex quinquefasciatus and those infected with CxFV Izabal by intrathoracic inoculation were administered WNV-infectious blood meals. Infection, dissemination, and transmission of WNV were measured by plaque titration on Vero cells of individual mosquito bodies, legs, or saliva, respectively, two weeks following WNV exposure. Additional groups of Cx. quinquefasciatus were intrathoracically inoculated with WNV alone or WNV+CxFV Izabal simultaneously, and saliva collected nine days post inoculation. Growth of WNV in Aedes albopictus C6/36 cells or Cx. quinquefasciatus was not inhibited by prior infection with CxFV Izabal. There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05). However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014). Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva.

Conclusions: In the sequential infection experiments, prior infection with CxFV Izabal had no significant impact on WNV replication, infection, dissemination, or transmission by Cx. quinquefasciatus, however WNV transmission was enhanced in the Honduras colony when mosquitoes were inoculated simultaneously with both viruses.

Show MeSH
Related in: MedlinePlus