Mosquito aging modulates the development, virulence and transmission potential of pathogens
Data files
Sep 27, 2023 version files 3.43 MB

fig2_oocyst_data.txt

fig2_sporozoite_data.txt

fig3_survival_data.txt

fig4_EIP_data.txt

fig5_vectorial_capacity_data.txt

README.md

Rscript_mosquito_age_infection.R
Nov 05, 2023 version files 3.42 MB

fig2_oocyst_data.txt

fig2_sporozoite_data.txt

fig3_survival_data.txt

fig4_EIP_data.txt

fig5_vectorial_capacity_data.txt

README.md
Abstract
Host age variation is a striking source of heterogeneity that can shape the evolution and transmission dynamic of pathogens. Compared to vertebrate systems, our understanding of the impact of host age on invertebratepathogen interactions remains limited. We examined the influence of mosquito age on key lifehistory traits driving human malaria transmission. Females of Anopheles coluzzii, a major malaria vector, belonging to three age classes (4, 8, and 12 dayold), were experimentally infected with Plasmodium falciparum field isolates. Our findings revealed reduced competence in 12dayold mosquitoes, characterized by lower oocyst/sporozoite rates and intensities compared to younger mosquitoes. Despite shorter median longevities in older age classes, infected 12dayold mosquitoes exhibited improved survival, suggesting that the infection might act as a fountain of youth for older mosquitoes specifically. The timing of sporozoite appearance in the salivary glands remained consistent across mosquito age classes, with an extrinsic incubation period of approximately 13 days. Integrating these results into an epidemiological model revealed a lower vectorial capacity for older mosquitoes compared to younger ones, albeit still substantial due to extended longevity in the presence of infection. Considering age heterogeneity provides valuable insights for ecological and epidemiological studies, informing targeted control strategies to mitigate pathogen transmission.
README: Mosquito aging modulates the development, virulence and transmission potential of pathogens
https://doi.org/10.5061/dryad.n02v6wx3n
5 datasets + 1 R script corresponding to the statistical analysis of the data and the modeling of vectorial capacity
Description of the data and file structure
Analysis of the effect of age on oocyst prevalence and intensity in An. coluzzii "fig2_oocyst_data.txt" has 4 columns:
* mosquito_id : a unique code for each dissected mosquito (n= 605)
* age_class : a 3level categorical variable corresponding to each of the three age group (12, 8 and 4dayold)
* isolate : a 4level categorical variable corresponding to each of the four gametocyte carriers (replicates)
* oocyst : number of developed oocyst in each mosquito midgut
Analysis of the effect of age on sporozoite prevalence and intensity in An. coluzzii
"fig2_sporozoite_data.txt" has 5 columns:
* mosquito_id : a unique code for each dissected mosquito (n= 729)
* age_class : a 3level categorical variable corresponding to each of the three age group (12, 8 and 4dayold)
* isolate : a 4level categorical variable corresponding to each of the four gametocyte carriers (replicates)
* Ct : number of cycle during the qPCR (this is a proxy of the quantity of parasite DNA in salivary glands)
* NB: this variable includes NA values which mean that no amplification occured and hence that the sample is negative
* positive: a binary variable corresponding to the infection status of mosquitoes (1: presence of, 0: absence of sporozoite)
Analysis of the effect of age and infection on mosquito survival "fig3_survival_data.txt" has 8 columns:
* mosquito_id : a unique code for each tracked mosquito (n= 657)
* cup: a code for each paper cup containing mosquitoes (n=48 cups of ~15 mosquitoes (range = 418))
* The naming convention for each cup follows a structured pattern: the first two letters represent one of
* the three age groups (G1, G2, or G3), the third letter indicates the ID of the parasite isolate (A to D),
* the fourth and fifth letters signify whether the mosquitoes were exposed (yes) or not (no) to the infectious blood meal,
* and the final letter specifies the cup number (1 or 2) for each group, isolate, exposure status.
* age_class : a 3level categorical variable corresponding to each of the three age group (12, 8 and 4dayold)
* isolate : a 4level categorical variable corresponding to each of the four gametocyte carriers (replicates)
* exposure : a twolevel categorical variable corresponding to whether mosquitoes received an infectious (yes) or uninfectious bloodmeal (no)
* infection_status: a 3level categorical variable corresponding to whether mosquitoes were uninfected controls, became infected upon exposure or remained uninfected upon exposure
* daysPI: the day (time postinfection) of mosquito death
* censor: censoring indicator (1 indicates that the response is a time at death, 0 indicates that the individual was alive when last seen). because all mosquitoes were followed until death, this indicator is 1 for every mosquito
Analysis of the effect of age on the parasite's EIP "fig4_EIP_data.txt" has 7 columns:
* mosquito_id : a unique code for each dissected mosquito (n= 802)
* age_class : a 2level categorical variable corresponding to each of the two age group (12 and 4dayold)
* isolate : a 3level categorical variable corresponding to each of the three gametocyte carriers (replicates)
* dpi : day (time postinfection) at which mosquitoes were dissected
* oocyst : number of developed oocyst in each mosquito midgut
* broken_oocyst: number of ruptured oocysts (NB: there are some NA values for dpi 6 because broken oocysts are unlikely
* to occur at this timepoint and were therefore not recorded)
* spz: a binomial variable corresponding to the presence (1) or absence (0) of sporozoite in mosquito salivary glands
* (NB: there are some NA values for dpi 6 because sporozoites are unlikely to occur at this timepoint and were therefore not recorded. A few additional NA are observed beyond dpi 6 when mosquito salivary glands were lost during the dissection)
Analysis of the effect of age on vectorial capacity "fig5_vectorial_capacity_data.txt" has 3 columns:
* scenario : a 3level categorical variable corresponding to each scenario
* age_class : a 2level categorical variable corresponding to each of the two age group (12 and 4dayold)
* vectorial_capacity: the response variable simulated from the mathematical model
Code/Software
1 R script "Rscript_mosquito_age_infection" corresponding to the analysis of the 5 data set presented above.