Limits...
Wolbachia induces density-dependent inhibition to dengue virus in mosquito cells.

Lu P, Bian G, Pan X, Xi Z - PLoS Negl Trop Dis (2012)

Bottom Line: We then compared Wolbachia density between transinfected Ae. aegypti and naturally infected Ae. albopictus.The results show that Wolbachia density in midgut, fatbody and salivary gland of Ae. albopictus is 80-, 18-, and 24-fold less than that of Ae. aegypti, respectively.Our results will aid in understanding the mechanism of Wolbachia-mediated pathogen interference and developing novel methods to block disease transmission by mosquitoes carrying native Wolbachia infections.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA.

ABSTRACT
Wolbachia is a maternal transmitted endosymbiotic bacterium that is estimated to infect up to 65% of insect species. The ability of Wolbachia to both induce viral interference and spread into mosquito vector population makes it possible to develop Wolbachia as a biological control agent for dengue control. While Wolbachia induces resistance to dengue virus in the transinfected Aedes aegypti mosquitoes, a similar effect was not observed in Aedes albopictus, which naturally carries Wolbachia infection but still serves as a dengue vector. In order to understand the mechanism of this lack of Wolbachia-mediated viral interference, we used both Ae. albopictus cell line (Aa23) and mosquitoes to characterize the impact of Wolbachia on dengue infection. A serial of sub-lethal doses of antibiotic treatment was used to partially remove Wolbachia in Aa23 cells and generate cell cultures with Wolbachia at different densities. We show that there is a strong negative linear correlation between the genome copy of Wolbachia and dengue virus with a dengue infection completely removed when Wolbacha density reaches a certain level. We then compared Wolbachia density between transinfected Ae. aegypti and naturally infected Ae. albopictus. The results show that Wolbachia density in midgut, fatbody and salivary gland of Ae. albopictus is 80-, 18-, and 24-fold less than that of Ae. aegypti, respectively. We provide evidence that Wolbachia density in somatic tissues of Ae. albopictus is too low to induce resistance to dengue virus. Our results will aid in understanding the mechanism of Wolbachia-mediated pathogen interference and developing novel methods to block disease transmission by mosquitoes carrying native Wolbachia infections.

Show MeSH

Related in: MedlinePlus

Generation of Aa23 cells with different Wolbachia density.Cells were treated using sub-lethal doses of rifampicin for a different time periods. Three dosages (0.05 µg/ml, 0.5 µg/ml and 5 µg/ml) and four time periods (4 h, 10 h, 40 h and 70 h) were used. The genome copies of wsp were measure by q-PCR, normalized by host gene actin. Error bars are standard errors of the mean of at least three biological replicates. Statistical significance is represented by letters above each column, with different letters signifying distinct statistical groups. Student's t test: a vs. b, P<0.001; b vs. c, P<0.001; d vs. a, P<0.05.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3404113&req=5

pntd-0001754-g002: Generation of Aa23 cells with different Wolbachia density.Cells were treated using sub-lethal doses of rifampicin for a different time periods. Three dosages (0.05 µg/ml, 0.5 µg/ml and 5 µg/ml) and four time periods (4 h, 10 h, 40 h and 70 h) were used. The genome copies of wsp were measure by q-PCR, normalized by host gene actin. Error bars are standard errors of the mean of at least three biological replicates. Statistical significance is represented by letters above each column, with different letters signifying distinct statistical groups. Student's t test: a vs. b, P<0.001; b vs. c, P<0.001; d vs. a, P<0.05.

Mentions: To study how the density of wAlbB can influence its induced resistance to DENV in Aa23 cell line, we used sub-lethal doses of rifampicin to partially remove Wolbachia and generated cell cultures with Wolbachia at different densities. Three dosages (0.05 µg/ml, 0.5 µg/ml and 5 µg/ml) with four treatment times (4 h, 10 h, 40 h and 70 h), resulting in a total of 12 treatments, were designed to make Wolbachia density cover a broad range. A mock treatment (control) was included to treat cells with only methanol solvent for the above four time periods. As a result (Fig. 2), we generated a serial of cell cultures with different Wolbachia densities, with a highest at 953.2 wsp/actin (from 0.05 µg/ml and 4 h) and a lowest at 18.0 wsp/actin (from 5 µg/ml and 70 h). Wolbachia density significantly decreased with an increase in treatment dose. Within each dosage, no significant difference in Wolbachia density is observed among four treatment times. This indicates a treatment for 4 h can effectively remove Wolbachia and a further increase in treatment time will not significantly enhance the inhibitory effect of rifampicin on Wolbachia. For example, a treatment at dosage of 5 µg/ml for 4 h can dramatically reduce Wolbachia to a very low level (75.2 wsp/actin), compared to the mock treatment (1,888.3 wsp/actin). Further increasing treatment time at this dose will not significantly change the Wolbachia density, resulting in 74.1 wsp/actin (10 h), 52.4 wsp/actin (40 h), and 18.0 wsp/actin (70 h, Fig. 2).


Wolbachia induces density-dependent inhibition to dengue virus in mosquito cells.

Lu P, Bian G, Pan X, Xi Z - PLoS Negl Trop Dis (2012)

Generation of Aa23 cells with different Wolbachia density.Cells were treated using sub-lethal doses of rifampicin for a different time periods. Three dosages (0.05 µg/ml, 0.5 µg/ml and 5 µg/ml) and four time periods (4 h, 10 h, 40 h and 70 h) were used. The genome copies of wsp were measure by q-PCR, normalized by host gene actin. Error bars are standard errors of the mean of at least three biological replicates. Statistical significance is represented by letters above each column, with different letters signifying distinct statistical groups. Student's t test: a vs. b, P<0.001; b vs. c, P<0.001; d vs. a, P<0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3404113&req=5

pntd-0001754-g002: Generation of Aa23 cells with different Wolbachia density.Cells were treated using sub-lethal doses of rifampicin for a different time periods. Three dosages (0.05 µg/ml, 0.5 µg/ml and 5 µg/ml) and four time periods (4 h, 10 h, 40 h and 70 h) were used. The genome copies of wsp were measure by q-PCR, normalized by host gene actin. Error bars are standard errors of the mean of at least three biological replicates. Statistical significance is represented by letters above each column, with different letters signifying distinct statistical groups. Student's t test: a vs. b, P<0.001; b vs. c, P<0.001; d vs. a, P<0.05.
Mentions: To study how the density of wAlbB can influence its induced resistance to DENV in Aa23 cell line, we used sub-lethal doses of rifampicin to partially remove Wolbachia and generated cell cultures with Wolbachia at different densities. Three dosages (0.05 µg/ml, 0.5 µg/ml and 5 µg/ml) with four treatment times (4 h, 10 h, 40 h and 70 h), resulting in a total of 12 treatments, were designed to make Wolbachia density cover a broad range. A mock treatment (control) was included to treat cells with only methanol solvent for the above four time periods. As a result (Fig. 2), we generated a serial of cell cultures with different Wolbachia densities, with a highest at 953.2 wsp/actin (from 0.05 µg/ml and 4 h) and a lowest at 18.0 wsp/actin (from 5 µg/ml and 70 h). Wolbachia density significantly decreased with an increase in treatment dose. Within each dosage, no significant difference in Wolbachia density is observed among four treatment times. This indicates a treatment for 4 h can effectively remove Wolbachia and a further increase in treatment time will not significantly enhance the inhibitory effect of rifampicin on Wolbachia. For example, a treatment at dosage of 5 µg/ml for 4 h can dramatically reduce Wolbachia to a very low level (75.2 wsp/actin), compared to the mock treatment (1,888.3 wsp/actin). Further increasing treatment time at this dose will not significantly change the Wolbachia density, resulting in 74.1 wsp/actin (10 h), 52.4 wsp/actin (40 h), and 18.0 wsp/actin (70 h, Fig. 2).

Bottom Line: We then compared Wolbachia density between transinfected Ae. aegypti and naturally infected Ae. albopictus.The results show that Wolbachia density in midgut, fatbody and salivary gland of Ae. albopictus is 80-, 18-, and 24-fold less than that of Ae. aegypti, respectively.Our results will aid in understanding the mechanism of Wolbachia-mediated pathogen interference and developing novel methods to block disease transmission by mosquitoes carrying native Wolbachia infections.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA.

ABSTRACT
Wolbachia is a maternal transmitted endosymbiotic bacterium that is estimated to infect up to 65% of insect species. The ability of Wolbachia to both induce viral interference and spread into mosquito vector population makes it possible to develop Wolbachia as a biological control agent for dengue control. While Wolbachia induces resistance to dengue virus in the transinfected Aedes aegypti mosquitoes, a similar effect was not observed in Aedes albopictus, which naturally carries Wolbachia infection but still serves as a dengue vector. In order to understand the mechanism of this lack of Wolbachia-mediated viral interference, we used both Ae. albopictus cell line (Aa23) and mosquitoes to characterize the impact of Wolbachia on dengue infection. A serial of sub-lethal doses of antibiotic treatment was used to partially remove Wolbachia in Aa23 cells and generate cell cultures with Wolbachia at different densities. We show that there is a strong negative linear correlation between the genome copy of Wolbachia and dengue virus with a dengue infection completely removed when Wolbacha density reaches a certain level. We then compared Wolbachia density between transinfected Ae. aegypti and naturally infected Ae. albopictus. The results show that Wolbachia density in midgut, fatbody and salivary gland of Ae. albopictus is 80-, 18-, and 24-fold less than that of Ae. aegypti, respectively. We provide evidence that Wolbachia density in somatic tissues of Ae. albopictus is too low to induce resistance to dengue virus. Our results will aid in understanding the mechanism of Wolbachia-mediated pathogen interference and developing novel methods to block disease transmission by mosquitoes carrying native Wolbachia infections.

Show MeSH
Related in: MedlinePlus