Browsing by Author "Gryseels, S."

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Arenavirus infection correlates with lower survival of its natural rodent host in a long-term capture-mark-recapture study
(2018) Mariën, J.; Sluydts, V.; Borremans, B.; Gryseels, S.; Broecke, B. V.; Sabuni, C. A.; Katakweba, A. A. S.; Mulungu, L. S.; Günther, S.; de Bellocq, J. G.; Massawe, A. W.; Leirs, H
Background: Parasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success. When host population densities fluctuate, low levels of virulence with limited impact on the host are expected, as this should increase the likelihood of surviving periods of low host density. We examined the effects of Morogoro arenavirus on the survival and recapture probability of multimammate mice (Mastomys natalensis) using a seven-year capture-mark-recapture time series. Mastomys natalensis is the natural host of Morogoro virus and is known for its strong seasonal density fluctuations. Results: Antibody presence was negatively correlated with survival probability (effect size: 5–8% per month depending on season) but positively with recapture probability (effect size: 8%). Conclusions: The small negative correlation between host survival probability and antibody presence suggests that either the virus has a negative effect on host condition, or that hosts with lower survival probability are more likely to obtain Morogoro virus infection, for example due to particular behavioural or immunological traits. The latter hypothesis is supported by the positive correlation between antibody status and recapture probability which suggests that risky behaviour might increase the probability of becoming infected.
Genetic distinction between contiguous urban and rural multimammate mice in Tanzania despite gene flow
(Journal of evolutionary biology., 2016) Gryseels, S.; Goüy de Bellocq, J.; Makundi, R.; Vanmechelen, K.; Broeckhove, J.; Mazoch, V.; Šumbera, R.; Zima Jr, J.; Leirs, H.; Baird, S. J. E.
Special conditions are required for genetic differentiation to arise at a localgeographical scale in the face of gene ﬂow. The Natal multimammatemouse, Mastomys natalensis, is the most widely distributed and abundantrodent in sub-Saharan Africa. A notorious agricultural pest and a naturalhost for many zoonotic diseases, it can live in close proximity to humansand appears to compete with other rodents for the synanthropic niche. Wesurveyed its population genetic structure across a 180-km transect in centralTanzania along which the landscape varied between agricultural land in arural setting and natural woody vegetation, rivers, roads and a city (Moro-goro). We sampled M. natalensis across 10 localities and genotyped 15microsatellite loci from 515 individuals. Hierarchical STRUCTURE analysesshow a K-invariant pattern distinguishing Morogoro suburbs (located in thecentre of the transect) from nine surrounding rural localities. Landscapeconnectivity analyses in Circuitscape and comparison of rainfall patternssuggest that neither geographical isolation nor natural breeding asynchronycould explain the genetic differentiation of the urban population. Using theisolation-with-migration model implemented in IMa2, we inferred that asplit between suburban and rural populations would have occurred recently(<150 years ago) with higher urban effective population density consistentwith an urban source to rural sink of effective migration. The observedgenetic differentiation of urban multimammate mice is striking given theuninterrupted distribution of the animal throughout the landscape and thehigh estimates of effective migration (2NeM = 3.0 and 29.7), suggesting astrong selection gradient across the urban boundary
Genetic structure and diversity of the black and rufous sengi in Tanzanian coastal forests
(Journal of Zoology, 2016) Sabuni, C. A.; Van Houtte, N.; Gryseels, S.; Maganga, S. L. S.; Makundi, Rhodes H.; Leirs, H.; Goüy de Bellocq, J.
The black and rufous sengi Rhynchocyon petersi is restricted to the Eastern ArcMountains and coastal forests of East Africa and considered vulnerable because ofhabitat fragmentation and degradation. Coastal forests are believed to have beenisolated from each other for thousands of years due to climatic changes. SinceR. petersi is described as strongly dependent on its forest habitat, we hypothesizedthat R. petersi from different forests would show genetic divergence. We investi-gated the genetic structure and diversity of this species in four coastal forests inTanzania using eight microsatellites and cytochrome b sequences. In total, 45 indi-viduals were captured after strenuous sampling efforts. For comparative purposeswe also sequenced the cytochrome b of 57 individuals from a sympatric rodent for-est species, Beamys hindei. The results indicate extant R. petersi have descendedfrom a single population of high effective size (Ne) with no forest-distinctive sig-nal. In contrast, B. hindei is more genetically structured: Although the most com-mon haplotype is found in the three closest forests, each forest harbours privatehaplotypes. Moreover, B. hindei Ne appeared 10 times smaller than R. petersi inZaraninge forest. While B. hindei results are consistent with the scenario of long-term isolation of coastal forests, the R. petersi are not. We suggest R. petersi mayless depend on forest habitat than previously suspected, consistent with anecdotalreports of sengis nesting in intervening agricultural habitat. From a conservationviewpoint, this sengi species therefore appears robust to the current spatial andtemporal scale of habitat fragmentation.
Polymorphism in vkorc1 gene of natal multimammate Mice, Mastomys natalensis, in Tanzania
(Journal of Heredity, 2015) Gryseels, S.; Leirsa, H.; Makundi, R.; De Bellocq, J. G.
Resistance of rodents to anticoagulant rodenticides has emerged in several areas across the world. Single nucleotide mutations in the vkorc1 gene have been shown to elicit various levels of anticoagulant resistance, and these mutations are prevalent in several Rattus and Mus musculus populations. In sub-Saharan Africa, the Natal multimammate mouse, Mastomys natalensis, is one of the most damaging pests to crops, and anticoagulant poisons such as bromadiolone are frequently used to control these rodents in agricultural fields. Here, we investigate if vkorc1 shows any polymorphism in natural populations of M. natalensis. We sequenced the third exon of vkorc1 of 162 M. natalensis captured from 14 different agricultural sites in Morogoro Region, Tanzania. In addition to 6 SNPs in the noncoding flanking region, we detected 3 nonsynonymous SNPs in this exon: 10 animals (6.2%) carried a Leu108Val variant, 2 animals (1.2%) an Ala140Thr variant, and 1 animal (0.6 %) an Arg100His variant, all 3 in heterozygous form. Ala140Thr is just one residue from a mutation known to be involved in anticoagulant resistance in Rattus and Mus. While in vitro or in vivo experiments are needed to link vkorc1 genetic polymorphisms to level of VKOR activity and anticoagulant susceptibility, our results suggest that M. natalensis individuals may vary in their response to anticoagulant rodenticides. This is the first vkorc1 sequence data from a species outside the Rattus or Mus genera, and for the first time from a rodent species endemic to Africa.
When viruses don’t go viral: the importance of host phylogeographic structure in the spatial spread of arenaviruses
(Public Library of Science, 2017) Gryseels, S.; Baird, S. J. E.; Borremans, B.; Makundi, R.; Leirs, H.; Bellocq, J. G.
Many emerging infections are RNA virus spillovers from animal reservoirs. Reservoir identification is necessary for predicting the geographic extent of infection risk, but rarely are taxonomic levels below the animal species considered as reservoir, and only key circumstances in nature and methodology allow intrinsic virus-host associations to be distinguished from simple geographic (co-)isolation. We sampled and genetically characterized in detail a contact zone of two subtaxa of the rodent Mastomys natalensis in Tanzania. We find two distinct arenaviruses, Gairo and Morogoro virus, each spatially confined to a single M. natalensis subtaxon, only co-occurring at the contact zone’s centre. Inter-subtaxon hybridization at this centre and a continuum of quality habitat for M. natalensis show that both viruses have the ecological opportunity to spread into the other substaxon’s range, but do not, strongly suggesting host-intrinsic barriers. Such barriers could explain why human cases of another M. natalensisborne arenavirus, Lassa virus, are limited to West Africa