Limits...
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.

Show MeSH

Related in: MedlinePlus

Localization of CxFV Izabal and WNV to head tissues in co-infected mosquitoes.A) Uninfected head tissues of Cx. quinquefasciatus stained with AlexaFluor 594 (red). White arrow depicts non-specific staining of debris. B) Head tissues of CxFV Izabal-infected Cx. quinquefasciatus, harvested 7 DPI. CxFV Izabal stained with AlexaFluor 594. C) Head tissues of WNV-infected Cx. quinquefasciatus, harvested 9 DPI. WNV stained with AlexaFluor 488 (green). D) Co-infected head tissues of Cx. quinquefasciatus. Mosquito inoculated simultaneously with CxFV Izabal and WNV, harvested 9 DPI. CxFV Izabal stained with AlexaFluor 594 (red) and WNV with Alexa 488 (green). White arrow denotes non-specific staining of debris.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2864301&req=5

pntd-0000671-g008: Localization of CxFV Izabal and WNV to head tissues in co-infected mosquitoes.A) Uninfected head tissues of Cx. quinquefasciatus stained with AlexaFluor 594 (red). White arrow depicts non-specific staining of debris. B) Head tissues of CxFV Izabal-infected Cx. quinquefasciatus, harvested 7 DPI. CxFV Izabal stained with AlexaFluor 594. C) Head tissues of WNV-infected Cx. quinquefasciatus, harvested 9 DPI. WNV stained with AlexaFluor 488 (green). D) Co-infected head tissues of Cx. quinquefasciatus. Mosquito inoculated simultaneously with CxFV Izabal and WNV, harvested 9 DPI. CxFV Izabal stained with AlexaFluor 594 (red) and WNV with Alexa 488 (green). White arrow denotes non-specific staining of debris.

Mentions: A significantly higher percentage of Honduras Cx. quinquefasciatus transmitted WNV when co-inoculated simultaneously with CxFV Izabal (98%, n = 53) than when inoculated with WNV alone (69%, n = 36) (p = 0.0014, Fisher Exact test) (Fig. 6). The percentage of Sebring Cx. quinquefasciatus that transmitted WNV when co-inoculated simultaneously with CxFV Izabal (93%, n = 27) was not significantly different from those inoculated with WNV alone (88%, n = 66) (p>0.05, Fisher exact test) (Fig. 6). The percentage of intrathoracically-inoculated specimens that transmitted WNV alone was also significantly less in the Honduras colony as compared with the Sebring colony, suggesting a more effective salivary gland barrier to WNV in the Honduras colony (p = 0.033, Fisher exact test); 87% of Sebring specimens (n = 66) transmitted WNV compared with only 69% (n = 36) of the Honduras specimens. For the Sebring colony, the average WNV titer in salivary expectorates for specimens inoculated with WNV only was 4.4 log10 pfu (n = 58), and not significantly different from an average titer of 4.7 log10 pfu in the expectorates of WNV+CxFV Izabal group (n = 25) (Student's two-tailed t-test, p = 0.11). For the Honduras colony, the average WNV titer in salivary expectorates for specimens inoculated with WNV only was 4.6 log10 pfu (n = 25) compared with 4.8 log10 pfu in the WNV+CxFV Izabal group (n = 52) (Student's two-tailed t-test, p = 0.38). For these groups, co-inoculated mosquitoes that transmitted WNV also contained CxFV Izabal in their saliva and mosquitoes that did not transmit WNV also did not transmit CxFV (n = 12). Mosquitoes infected with CxFV Izabal only (n = 5) did not have CxFV Izabal in their saliva. Midgut (Fig. 7) and head tissues (Fig. 8) of mosquitoes inoculated simultaneously with CxFV Izabal and WNV were observed to be infected with both viruses by IFA.


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)

Localization of CxFV Izabal and WNV to head tissues in co-infected mosquitoes.A) Uninfected head tissues of Cx. quinquefasciatus stained with AlexaFluor 594 (red). White arrow depicts non-specific staining of debris. B) Head tissues of CxFV Izabal-infected Cx. quinquefasciatus, harvested 7 DPI. CxFV Izabal stained with AlexaFluor 594. C) Head tissues of WNV-infected Cx. quinquefasciatus, harvested 9 DPI. WNV stained with AlexaFluor 488 (green). D) Co-infected head tissues of Cx. quinquefasciatus. Mosquito inoculated simultaneously with CxFV Izabal and WNV, harvested 9 DPI. CxFV Izabal stained with AlexaFluor 594 (red) and WNV with Alexa 488 (green). White arrow denotes non-specific staining of debris.
© Copyright Policy
Related In: Results  -  Collection

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

pntd-0000671-g008: Localization of CxFV Izabal and WNV to head tissues in co-infected mosquitoes.A) Uninfected head tissues of Cx. quinquefasciatus stained with AlexaFluor 594 (red). White arrow depicts non-specific staining of debris. B) Head tissues of CxFV Izabal-infected Cx. quinquefasciatus, harvested 7 DPI. CxFV Izabal stained with AlexaFluor 594. C) Head tissues of WNV-infected Cx. quinquefasciatus, harvested 9 DPI. WNV stained with AlexaFluor 488 (green). D) Co-infected head tissues of Cx. quinquefasciatus. Mosquito inoculated simultaneously with CxFV Izabal and WNV, harvested 9 DPI. CxFV Izabal stained with AlexaFluor 594 (red) and WNV with Alexa 488 (green). White arrow denotes non-specific staining of debris.
Mentions: A significantly higher percentage of Honduras Cx. quinquefasciatus transmitted WNV when co-inoculated simultaneously with CxFV Izabal (98%, n = 53) than when inoculated with WNV alone (69%, n = 36) (p = 0.0014, Fisher Exact test) (Fig. 6). The percentage of Sebring Cx. quinquefasciatus that transmitted WNV when co-inoculated simultaneously with CxFV Izabal (93%, n = 27) was not significantly different from those inoculated with WNV alone (88%, n = 66) (p>0.05, Fisher exact test) (Fig. 6). The percentage of intrathoracically-inoculated specimens that transmitted WNV alone was also significantly less in the Honduras colony as compared with the Sebring colony, suggesting a more effective salivary gland barrier to WNV in the Honduras colony (p = 0.033, Fisher exact test); 87% of Sebring specimens (n = 66) transmitted WNV compared with only 69% (n = 36) of the Honduras specimens. For the Sebring colony, the average WNV titer in salivary expectorates for specimens inoculated with WNV only was 4.4 log10 pfu (n = 58), and not significantly different from an average titer of 4.7 log10 pfu in the expectorates of WNV+CxFV Izabal group (n = 25) (Student's two-tailed t-test, p = 0.11). For the Honduras colony, the average WNV titer in salivary expectorates for specimens inoculated with WNV only was 4.6 log10 pfu (n = 25) compared with 4.8 log10 pfu in the WNV+CxFV Izabal group (n = 52) (Student's two-tailed t-test, p = 0.38). For these groups, co-inoculated mosquitoes that transmitted WNV also contained CxFV Izabal in their saliva and mosquitoes that did not transmit WNV also did not transmit CxFV (n = 12). Mosquitoes infected with CxFV Izabal only (n = 5) did not have CxFV Izabal in their saliva. Midgut (Fig. 7) and head tissues (Fig. 8) of mosquitoes inoculated simultaneously with CxFV Izabal and WNV were observed to be infected with both viruses by IFA.

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