Non-infected Females Research Articles

Post-Traumatic Stress after Corona Virus Disease 19 (COVID-19): The Role of Gender and Distressing Social Media Exposure as Risk Factors

Direct (e.g. being in contact with the virus) and indirect traumatic experiences (e.g. Distressing Social Media Exposure: DSME) of the COVID-19 pandemic led to a variety of psychological and psychosocial consequences. They represent COVID-19-related Posttraumatic Stress Symptoms (PTSS) risk factors, whereby their interactions and their relations to gender have not yet been explored.
 1368 participants filled in an online survey between the January and March 2021. Risk Ratios and 95% CIs were calculated to estimate the magnitude of the risk related to a reported COVID-19 infection, reported COVID-19 symptom severity, gender and DSME on COVID-19-related PTSS. A 2x2x2 ANOVA was used to determine the main and interaction effects of a COVID-19 infection, gender and DSME on COVID-19 PTSS.
 174 (13%) participants reported COVID-19-related PTSS, which was more prominent in female (n=127; 15%), than in male participants (n=49; 9%). Individuals, who reported to have or have had a COVID-19 infection showed a significantly higher risk (RR=2.50, LCI=1.87, UCI=3.32) for COVID-19-related PTSS, especially when severe COVID-19 symptoms were reported (RR=4.01, LCI=2.66, UCI=6.03). Whereas non-infected females were at higher risk than males (p≤.001, LCI=16.96,UCI=23.81), a non-significant mean difference of 6.54 (p=.159, LCI=-14.62,UCI=1.54) between males and females was found when COVID-19 infections were reported. DSME increased the Risk Ratios by 2.81 (LCI=2.08, UCI=3.79) and was more prominent in males.
 The results from this study indicate that severe COVID-19 symptoms, DSME and female gender are risk factors for COVID-19 related PTSS. This underlines the need for effective public health measures for prevention.

The Infection of Paracalanid Copepods by the Alveolate Parasite Ellobiopsis chattoni Caullery, 1910 in a Subtropical Coastal Area

Paracalanid copepods, common in tropical zooplankton communities, are known hosts for a variety of parasites. Nevertheless, relatively little is known about the prevalence and consequences of parasitism in these copepods. In this study, we analyzed the relationship between two paracalanid copepods, Parvocalanus crassirostris and Paracalanus spp., with a common parasite, the alveolate protist Ellobiopsis chattoni, in a subtropical environment on the south-east Brazilian coast. We assessed the frequency and abundance of parasites in juveniles and adult male and female copepods. We observed that 22 out of 4014 Paracalanus spp. (0.55%) and 98 out of 3920 P. crassirostris were infected (2.5%). E. chattoni were rarely found in other taxa (about 0.05% for Oithona spp. and Acartia lilljeborgii). The parasites were most frequently attached to cephalosome appendages (73.6%), with up to four cells per copepod. The parasites were more prevalent in adults than juveniles, and adult females were more frequently infected than males. E. chattoni had a likely negative impact on copepod growth because the infected females were smaller than the non-infected females (p < 0.001). Females are usually bigger and live longer than males, which could account for their high frequency of infection.

The association of telomere maintenance and TERT expression with susceptibility to human papillomavirus infection in cervical epithelium.

The role of telomerase reverse transcriptase (TERT) induction and telomere maintenance in carcinogenesis including cervical cancer (CC) pathogenesis has been well established. However, it remains unclear whether they affect infection of high-risk human papillomavirus (hrHPV), an initiating event for CC development. Similarly, genetic variants at the TERT locus are shown to be associated with susceptibility to CC, but it is unclear whether these SNPs modify the risk for cervical HPV infection. Here we show that in CC-derived HeLa cells, TERT overexpression inhibits, while its depletion upregulates expression of Syndecan-1 (SDC-1), a key component for HPV entry receptors. The TCGA cohort of CC analyses reveals an inverse correlation between TERT and SDC-1 expression (R = -0.23, P = 0.001). We further recruited 1330 females (520 non-HPV and 810 hrHPV-infected) without CC or high-grade cervicalintraepithelial neoplasia to analyze telomeres in cervical epithelial cells and SNPs at rs2736098, rs2736100 and rs2736108, previously identified TERT SNPs for CC risk. Non-infected females exhibited age-related telomere shortening in cervical epithelial cells and their telomeres were significantly longer than those in hrHPV-infected group (1.31 ± 0.62 vs 1.19 ± 0.48, P < 0.001). There were no differences in rs2736098 and rs2736100 genotypes, but non-infected individuals had significantly a higher C-allele frequency (associated with higher TERT expression) while lower T-allele levels at rs2736108 compared with those in the hrHPV group (P = 0.020). Collectively, appropriate telomere maintenance and TERT expression in normal cervical cells may prevent CC by modulating hrHPV infection predisposition, although they are required for CC development and progression.

Phlebotomus papatasi Antimicrobial Peptides in Larvae and Females and a Gut-Specific Defensin Upregulated by Leishmania major Infection.

Phlebotomus papatasi is the vector of Leishmania major, causing cutaneous leishmaniasis in the Old World. We investigated whether P. papatasi immunity genes were expressed toward L. major, commensal gut microbes, or a combination of both. We focused on sand fly transcription factors dorsal and relish and antimicrobial peptides (AMPs) attacin and defensin and assessed their relative gene expression by qPCR. Sand fly larvae were fed food with different bacterial loads. Relish and AMPs gene expressions were higher in L3 and early L4 larval instars, while bacteria 16S rRNA increased in late L4 larval instar, all fed rich-microbe food compared to the control group fed autoclaved food. Sand fly females were treated with an antibiotic cocktail to deplete gut bacteria and were experimentally infected by Leishmania. Compared to non-infected females, dorsal and defensin were upregulated at early and late infection stages, respectively. An earlier increase of defensin was observed in infected females when bacteria recolonized the gut after the removal of antibiotics. Interestingly, this defensin gene expression occurred specifically in midguts but not in other tissues of females and larvae. A gut-specific defensin gene upregulated by L. major infection, in combination with gut-bacteria, is a promising molecular target for parasite control strategies.

Evaluation of Locally Isolated Entomopathogenic Fungi against Multiple Life Stages of Bactrocera zonata and Bactrocera dorsalis (Diptera: Tephritidae): Laboratory and Field Study.

Fruit flies including Bactrocera zonata and B. dorsalis (Diptera: Tephritidae) are considered major pests of orchard systems in Pakistan. This study evaluated the laboratory virulence, sub-lethal effects, horizontal transmission, greenhouse, and field-cage efficacy of locally isolated entomopathogenic fungi (EPF) against B. zonata and B. dorsalis. In virulence assays against third instars and adults, all 21 EPF isolates (Beauveria bassiana and Metarhizium anisopliae) tested were pathogenic and caused varying levels of mortality to the fruit flies. Based on the initial screening, four isolates (B. bassiana WG-21 and WG-18 and M. anisopliae WG-07 and WG-02) were selected for further study. The isolate WG-18 was the most virulent against larvae and adults of B. zonata and B. dorsalis followed by WG-21, WG-02, and WG-07. In both species, adults were more susceptible than larvae to all isolates, and pupae were the least susceptible. Isolates WG-18 and WG-21 strongly decreased female fecundity and fertility, the highest adult and larval mortality, and longest developmental time of larvae and pupae. Fungal conidia were disseminated passively from infected to healthy adults and induced significant mortality, particularly from infected males to non-infected females. In greenhouse and field-cage experiments, WG-18 and WG-21 were the most effective isolates in reducing adult emergence when applied to larvae and pupae of both fruit fly species. Our results indicate that B. bassiana isolates WG-18 and WG-21 were the most virulent against multiple life stages of B. zonata and B. dorsalis, and also exerted the strongest sub-lethal effects.

Non-invasive visualisation and identification of fluorescent Leishmania tarentolae in infected sand flies

Background: The leishmaniases are neglected diseases that affect some of the most vulnerable populations in the tropical and sub-tropical world. The parasites are transmitted by sand flies and novel strategies to control this neglected vector-borne disease are needed. Blocking transmission by targeting the parasite inside the phlebotomine vector offers potential in this regard. Some experimental approaches can be best performed by longitudinal study of parasites within flies, for which non-destructive methods to identify infected flies and to follow parasite population changes are required. Methods: Lutzomyia longipalpis were reared under standard insectary conditions at the Wellcome Centre for Molecular Parasitology. Flies were artificially infected with L. tarentolae expressing green fluorescent protein (GFP. Parasite counts were carried out 5 days post-infection and the percentage of infected flies and survival of infected females was established up to days 5 post-infection. Whole living females were visualised using an epifluorescence inverted microscope to detect the presence parasites inferred by a localised green fluorescent region in the upper thorax. Confirmation of infection was performed by localised-fluorescence of dissected flies and estimates of the parasite population. Results : Leishmania tarentolae was successfully transfected and expressed GFP in vitro. L. tarentolae-GFP Infected flies showed similar parasite populations when compared to non-transfected parasites ( L. tarentolae-WT). Survival of non-infected females was higher than L. tarentolae-infected groups, (Log-rank (Mantel-Cox) test, p<0.05). L. tarentolae-GFP infected females displayed an intense localised fluorescence in the thorax while other specimens from the same infected group did not. Localised fluorescent flies were dissected and showed higher parasite populations compared to those that did not demonstrate high concentrations in this region (t-test, p<0.005). Conclusion : These results demonstrate the feasibility of establishing a safe non-human infectious fluorescent Leishmania-sand fly infection model by allowing non-destructive imaging to signal the establishment of Leishmania infections in living sand flies.

Non-invasive visualisation and identification of fluorescent Leishmania tarentolae in infected sand flies.

Background: The leishmaniases are neglected diseases that affect some of the most vulnerable populations in the tropical and sub-tropical world. The parasites are transmitted by sand flies and novel strategies to control this neglected vector-borne disease are needed. Blocking transmission by targeting the parasite inside the phlebotomine vector offers potential in this regard. Some experimental approaches can be best performed by longitudinal study of parasites within flies, for which non-destructive methods to identify infected flies and to follow parasite population changes are required. Methods: Lutzomyia longipalpis were reared under standard insectary conditions at the Wellcome Centre for Molecular Parasitology. Flies were artificially infected with L. tarentolae expressing green fluorescent protein (GFP. Parasite counts were carried out 5 days post-infection and the percentage of infected flies and survival of infected females was established up to days 5 post-infection. Whole living females were visualised using an epifluorescence inverted microscope to detect the presence parasites inferred by a localised green fluorescent region in the upper thorax. Confirmation of infection was performed by localised-fluorescence of dissected flies and estimates of the parasite population. Results : Leishmania tarentolae was successfully transfected and expressed GFP in vitro. L. tarentolae-GFP Infected flies showed similar parasite populations when compared to non-transfected parasites ( L. tarentolae-WT). Survival of non-infected females was higher than L. tarentolae-infected groups, (Log-rank (Mantel-Cox) test, p<0.05). L. tarentolae-GFP infected females displayed an intense localised fluorescence in the thorax while other specimens from the same infected group did not. Localised fluorescent flies were dissected and showed higher parasite populations compared to those that did not demonstrate high concentrations in this region (t-test, p<0.005). Conclusion : These results demonstrate the feasibility of establishing a safe non-human infectious fluorescent Leishmania-sand fly infection model by allowing non-destructive imaging to signal the establishment of Leishmania infections in living sand flies.

Zika infection decreases Aedes aegypti locomotor activity but does not influence egg production or viability.

BACKGROUND Zika has emerged as a new public health threat after the explosive epidemic in Brazil in 2015. It is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. The knowledge of physiological, behavioural and biological features in virus-infected vectors may help the understanding of arbovirus transmission dynamics and elucidate their influence in vector capacity.OBJECTIVES We aimed to investigate the effects of Zika virus (ZIKV) infection in the behaviour of Ae. aegypti females by analysing the locomotor activity, egg production and viability.METHODOLOGY Ae. aegypti females were orally infected with ZIKV through an artificial feeder to access egg production, egg viability and locomotor activity. For egg production and viability assays, females were kept in cages containing an artificial site for oviposition and eggs were counted. Locomotor activity assays were performed in activity monitors and an average of 5th, 6th and 7th days after infective feeding was calculated.FINDINGS No significant difference in the number of eggs laid per females neither in their viability were found between ZIKV infected and non-infected females, regardless the tested pair of mosquito population and virus strain and the gonotrophic cycles. Locomotor activity assays were performed regardless of the locomotor activity in ZIKV infected females was observed, in both LD and DD conditions.MAIN CONCLUSIONS The lower locomotor activity may reduce the mobility of the mosquitoes and may explain case clustering within households reported during Zika outbreaks such as in Rio de Janeiro 2015. Nevertheless, the mosquitoes infected with ZIKV are still able to disseminate and to transmit the disease, especially in places where there are many oviposition sites.

Macrophage Migration Inhibitory Factor (MIF) Prevents Maternal Death, but Contributes to Poor Fetal Outcome During Congenital Toxoplasmosis.

Migration inhibitory factor (MIF) is a pro-inflammatory cytokine that plays important roles in physiology, pathology, immunology and parasitology, including the control of infection by protozoa parasites such as Toxoplasma gondii. As the MIF function in congenital toxoplasmosis is not fully elucidated yet, the present study brings new insights for T. gondii infection in the absence of MIF based on pregnant C57BL/6MIF-/- mouse models. Pregnant C57BL/6MIF-/- and C57BL/6WT mice were infected with 05 cysts of T. gondii (ME49 strain) on the first day of pregnancy (dop) and were euthanized at 8 dop. Non-pregnant and non-infected females were used as control. Our results demonstrated that MIF-/- mice have more accentuated change in body weight and succumbed to infection first than their WT counterparts. Otherwise, pregnancy outcome was less destructive in MIF-/- mice compared to WT ones, and the former had an increase in the mast cell recruitment and IDO expression and consequently presented less inflammatory cytokine production. Also, MIF receptor (CD74) was upregulated in MIF-/- mice, indicating that a compensatory mechanism may be required in this model of study. The global absence of MIF was associated with attenuation of pathology in congenital toxoplasmosis, but resulted in female death probably because of uncontrolled infection. Altogether, ours results demonstrated that part of the immune response that protects a pregnant female from T. gondii infection, favors fetal damage.

Symbiotic Bacteria Influence the Odor and Mating Preference of Their Hosts

In many species, chemical communication is a determining factor in mate choice. Some species use the composition of cuticular compounds to discriminate between potential mates. Moreover, the presence of parasites can also influence mate choice and alter the odor of an individual. In the current study, we tested the effect of the endosymbiont Wolbachia, which is naturally present in the terrestrial isopod Armadillidium vulgare and can induce male feminization in the species. We compared male attraction to different types of females (Wolbachia-free, females naturally infected by Wolbachia, Wolbachia-injected females, and females injected with a bacteria-free suspension). Our behavioral assays revealed that males consistently preferred Wolbachia-free females and that this preference correlates to changes in cuticular compounds. Males also preferred naturally infected females over Wolbachia-injected females. The ability of males to discriminate between females could result in Wolbachia impacting its host phenotype, thus affecting the odor of the host. Female odor is the result of an honest signal that makes it possible for males to discriminate between Wolbachia-infected and non-infected females. The male preference for Wolbachia-free females is adaptive, and long-term studies have demonstrated that such choices confer improved fitness.

DREADD-induced silencing of the medial amygdala reduces the preference for male pheromones and the expression of lordosis in estrous female mice.

Sexually naïve estrous female mice seek out male urinary pheromones; however, they initially display little receptive (lordosis) behavior in response to male mounts. Vomeronasal-accessory olfactory bulb inputs to the medial amygdala (Me) regulate courtship in female rodents. We used a reversible inhibitory chemogenetic technique (Designer Receptors Exclusively Activated by Designer Drugs; DREADDs) to assess the contribution of Me signaling to females' preference for male pheromones and improvement in receptivity normally seen with repeated testing. Sexually naïve females received bilateral Me injections of an adeno-associated virus carrying an inhibitory DREADD. Females were later ovariectomized, treated with ovarian hormones, and given behavioral tests following intraperitoneal injections of saline or clozapine-N-oxide (CNO; which hyperpolarizes infected Me neurons). CNO attenuated females' preference to investigate male vs. female urinary odors. Repeated CNO treatment also slowed the increase in lordosis otherwise seen in females given saline. However, when saline was given to females previously treated with CNO, their lordosis quotients were as high as other females repeatedly given saline. No disruptive behavioral effects of CNO were seen in estrous females lacking DREADD infections of the Me. Finally, CNO attenuated the ability of male pheromones to stimulate Fos expression in the Me of DREADD-infected mice but not in non-infected females. Our results affirm the importance of Me signaling in females' chemosensory preferences and in the acute expression of lordosis. However, they provide no indication that Me signaling is required for the increase in receptivity normally seen after repeated hormone priming and testing with a male.

Effects of Soybean Vein Necrosis Virus on Life History and Host Preference of Its Vector, Neohydatothrips variabilis, and Evaluation of Vector Status of Frankliniella tritici and Frankliniella fusca.

Soybean vein necrosis virus (SVNV) is an emerging Tospovirus that is now considered to be the most widespread soybean virus in the United States. SVNV is transmitted from plant-to-plant by soybean thrips, Neohydatothrips variabilis (Beach). We hypothesized that a positive interaction between the host plant, SVNV, and the vector may have resulted in the widespread distribution of the virus in a short span of time. Our study found that SVNV-infected N. variabilis females produced significantly more offspring compared with non-infected females. No other life-history trait varied between SVNV-infected and non-infected thrips. There was considerable variation in SVNV copy number in infected thrips ranging from 10(2) -10(6) Moreover, there was a significant negative correlation between SVNV copy number and fecundity in infected N. variabilis This suggests that excessive virus accumulation may result in lower viability of N. variabilis In choice tests, SVNV-infected N. variabilis preferred to feed on non-infected leaflets compared with infected leaflets. Vector competence assays indicated that Frankliniella tritici and Frankliniella fusca can transmit SVNV, but at a lower efficiency than N. variabilis Comparison of life history of between the primary and secondary vectors showed that N. variabilis had the highest fecundity, but F. tritici had the shortest development time and greatest larval survival. Taken together, the increased fecundity of SVNV-infected N. variabilis, their apparent preference for non-infected host plants, in conjunction with the ability of secondary vectors to survive and reproduce on soybean may, in part, explain the rapid spread of SVNV in the United States.

Tidal elevation and parasitism: patterns of infection by the rhizocephalan parasite Sacculina carcini in shore crabs Carcinus maenas

While the distinct zonation patterns of benthic organisms along intertidal elevation gradients have been extensively documented, relatively little is known about the impact that tidal elevation has on the distribution and abundance of marine parasites that are common in intertidal ecosystems. In this study, we investigated the distribution of shore crabs Carcinus maenas infected with the rhizocephalan parasite Sacculina carcini at 12 locations and in 3 adjacent habitats (intertidal mussel beds, intertidal bare sand flats and subtidal gullies) along a tidal elevation gradient in the Dutch Wadden Sea. Our sampling revealed that of the 27 629 crabs investigated, most infected crabs were found in the subtidal gullies and almost none on intertidal bare sand flats or mussel beds at all of the 12 locations. This probably resulted from a parasite-induced manipulation of infected crabs to behave like egg-bearing females which migrate towards deeper waters, as the same pattern was observed in the distribution of non-infected ovigerous females. The prevalence of both infected crabs and ovigerous females in the gullies was significantly correlated with water depth, and both tended to increase (albeit not significantly) with increasing salinity. As water depth and salinity are expected to affect larval survival of both parasites and crabs, this suggests that the migration into subtidal habitats may result in favourable conditions for reproduction and dispersal. By using a replicated and nested sampling design as well as a large sample size, our study significantly increases the limited understanding of parasite distributions along tidal elevation gradients.

Comparative evaluation of Amblyomma ovale ticks infected and noninfected by Rickettsia sp. strain Atlantic rainforest, the agent of an emerging rickettsiosis in Brazil

In 2010, a novel spotted fever group rickettsiosis was reported in the Atlantic rainforest coast of Brazil. The etiological agent was identified as Rickettsia sp. strain Atlantic rainforest, and the tick Amblyomma ovale was incriminated as the presumed vector. The present study evaluated under laboratory conditions four colonies of A. ovale: two started from engorged females that were naturally infected by Rickettsia sp. strain Atlantic rainforest (designated as infected groups); the two others started from noninfected females (designated as control groups). All colonies were reared in parallel from F0 engorged female to F2 unfed nymphs. Tick-naïve vesper mice (Calomys callosus) or domestic rabbits were used for feeding of each tick stage. Rickettsia sp. strain Atlantic rainforest was preserved by transstadial maintenance and transovarial transmission in A. ovale ticks for at least 2 generations (from F0 females to F2 nymphs), because nearly 100% of the tested larvae, nymphs, and adults from the infected groups were shown by PCR to contain rickettsial DNA. All vesper mice and rabbits infested by larvae and nymphs, and 50% of the rabbits infested by adults from the infected groups seroconverted, indicating that these tick stages were vector competent for Rickettsia sp. strain Atlantic rainforest. Expressive differences in mortality rates and reproductive performance were observed between engorged females from the infected and control groups, as indicated by 75.0% and 97.1% oviposition success, respectively, and significantly lower egg mass weight, conversion efficiency index, and percentage of egg hatching for the infected groups. Our results indicate that A. ovale can act as a natural reservoir for Rickettsia sp. strain Atlantic rainforest. However, due to deleterious effect caused by this rickettsial agent on engorged females, amplifier vertebrate hosts might be necessary for persistent perpetuation of Rickettsia sp. strain Atlantic rainforest in A. ovale under natural conditions.

Low temperature affects cattle tick reproduction but does not lead to transovarial transmission of Anaplasma marginale

Anaplasma marginale is an obligate intracellular pathogen that infects the erythrocytes of calves, causing bovine anaplasmosis. This rickettsia is biologically transmitted by several species of ticks. In tropical and subtropical regions of the world, Rhipicephalus microplus is the main vector. Due to their mobility and longevity, the adult males play an important role in the transmission of A. marginale to calves. Some studies have demonstrated that A. marginale can be intrastadially and interstadially transmitted in R. microplus, but the transovarial transmission has not been demonstrated so far. In the present study, we investigated the effects of low temperature on both the A. marginale migration from infected females to their offspring and reproductive parameters of the tick R. microplus. The larvae of R. microplus fed on a calf infected with the strain Jaboticabal of A. marginale. At the end of the parasitic phase, fully engorged females were incubated at either 18°C or 28°C for oviposition. Although A. marginale was detected in the salivary glands of the females, demonstrating that the ticks were successfully infected, the presence of rickettsia was not detected in the offspring. However, the preoviposition period of the non-infected females maintained at 18°C was longer than that of those maintained at 28°C. In addition, the average weight of the mass of eggs as well as the egg production efficiency (ratio of the egg mass weight to the female weight) of the females maintained at 18°C were significantly lower than those of the females incubated at 28°C. There was no larval hatching from the eggs maintained exclusively at 18°C, even at 65 days after female detachment. Hatching occurred only when the eggs maintained at 18°C were transferred to 28°C at 20 days after female detachment (18°C/28°C). We also verified a significantly higher larvae conversion efficiency (ratio of the larvae mass weight to the egg mass weight) in the group of females maintained exclusively at 28°C compared to those from the 18°C/28°C group. Collectively, our results reinforce that low temperature exerts negative effects on female fertility and egg development in R. microplus, although it has no influence on A. marginale transmission to the progeny. In the field, the detrimental effects of temperatures on tick reproductive fitness lead to a reduction of tick population, which may cause a decrease in the incidence of bovine anaplasmosis.

Comparative Evaluation of Infected and NoninfectedAmblyomma tristeTicks withRickettsia parkeri, the Agent of an Emerging Rickettsiosis in the New World

The distribution of Rickettsia parkeri in South America has been associated with Amblyomma triste ticks. The present study evaluated under laboratory conditions two colonies of A. triste: one started from engorged females that were naturally infected by R. parkeri (designated as infected group); the other started from noninfected females (designated as control group). Both colonies were reared in parallel for five consecutive generations. Tick-naïve domestic rabbits were used for feeding of each tick stage and generation. R. parkeri was preserved by transstadial maintenance and transovarial transmission in A. triste ticks for five consecutive generations, because all tested larvae, nymphs, and adults from the infected group were shown by PCR to contain rickettsial DNA. All rabbits infested by larvae, nymphs, and adults from the infected group seroconverted, indicating that these tick stages were all vector competent for R. parkeri. Expressive differences in mortality rates were observed between engorged nymphs from the infected and control groups, as indicated by 65.9% and 92.4% molting success, respectively. Our results indicate that A. triste can act as a natural reservoir for R. parkeri. However, due to deleterious effect caused by R. parkeri on engorged nymphs, amplifier vertebrate hosts might be necessary for natural long-term maintenance of R. parkeri in A. triste.

Replication of Clone 13, a Naturally Attenuated Avirulent Isolate of Rift Valley Fever Virus, inAedesandCulexmosquitoes

Rift Valley fever virus continues to cause large outbreaks of acute and febrile illness among humans and domestic animals in Africa. The high pathogenicity of the virus is mainly due to the non-structural protein derived from the S segment NSs, which was shown to inhibit the type I interferon expression at the transcriptional level and to suppress host cell RNA synthesis. Clone 13, a naturally attenuated clone containing a deletion of 70% in NSs, is a promising vaccine candidate as it has no pathogenicity for mice and is highly immunogenic leading to long-lasting immunity. If Clone 13 succeeds in inducing a transient viremia in inoculated animals, is a mosquito vector able to replicate Clone 13 and is the vector affected by viral infection? In this work, we orally infected two mosquito species, Aedes vexans and Culex pipiens quinquefasciatus, with the avirulent Clone 13. We showed that the mosquito Ae. vexans better replicated the avirulent Clone 13 than Cx. p. quinquefasciatus. Moreover, infection with Clone 13 did not cause any important changes in mosquito's life-history traits compared to noninfected females. Nevertheless, it is likely that Clone 13 would not be efficiently transmitted by mosquito vectors.

Patterns of house infestation dynamics by non-domiciliatedTriatoma dimidiatareveal a spatial gradient of infestation in rural villages and potential insect manipulation byTrypanosoma cruzi

Chagas disease is a major vector-borne parasitic disease in Latin America, primarily transmitted to humans by triatomine vectors. Non-domiciliated triatomine species such as Triatoma dimidiata in the Yucatan peninsula, Mexico, can transiently invade houses and are emerging as a major challenge to control Trypanosoma cruzi transmission to humans. We analyzed the spatio-temporal spreading of house infestation by T. dimidiata in four rural villages. Triatomines were collected in four rural villages over a 2 years period, and the spatio-temporal patterns of infestation were analyzed. Triatomines were consistently more abundant at the periphery of villages than in centers, indicating a much higher risk of T. cruzi transmission at the periphery. Male T. dimidiata were found further in the center of the village, while females remained closer to the periphery, suggesting differential dispersal capabilities between sexes, although the timing of dispersal appeared identical. Surprisingly, infected females were consistently collected in houses much further from the surrounding bushes than non-infected females, while the distribution of males was unaffected by their T. cruzi infection status, suggesting an increased dispersal capability in infected females. The spatial structure of infestation should be taken into account for the prioritization of vector control activities within villages, and spatially targeted interventions may be explored. A potential vector manipulation by T. cruzi, observed for the first time in triatomines, may favor parasite transmission to new hosts.

Effect of fungal infection on reproductive potential and survival time of Tetranychus urticae (Acari: Tetranychidae)

The effect of fungal infection on the reproductive potential of two-spotted spider mite, Tetranychus urticae, was evaluated as part of the full biocontrol potential of three entomopathogenic fungi by modeling of fecundity probability. Female mites (<or=2-day-old) on leaves were exposed to the sprays of Beauveria bassiana, Paecilomyces fumosoroseus and Metarhizium anisopliae at the concentrations of 1.13 x 10(3), 1.55 x 10(3) and 0.95 x 10(3) deposited conidia mm(-2) and then individually reared at 25 degrees C and 12:12 L:D for oviposition. Mite mortalities 10 days after spraying were 73.1, 75.4 and 67.9% in the fungal treatments versus 15.5% in control. On average, females infected by the three fungal species survived 5.8, 6.2 and 6.3 days, and laid 3.1, 4.0 and 4.0 eggs per capita, respectively. These were 3-4 fold lower than the control fecundity at 12.3. The cumulative probabilities [P(m <or= N)] for the counts of infected and non-infected (control) females laying m eggs per capita (m <or= N) during 10 days fit very well the equation P(m <or= N) = 1/[1 + exp(a + bm)] (r(2) >or= 0.98), yielding a solution to the probability for the female mites to achieve a specific fecundity {P(m <or= N)-P[m <or= (N - 1)]}. Consequently, the infected mites had 71-78% chance to lay <or=5 eggs per capita but only 5-8% to deposit >10 eggs despite some variation among the tested fungi. In contrast, the chances for the non-infected mites to achieve the low and high fecundities were 23 and 55%. The fitted probabilities provide a full coverage of the fecundity potential of infected versus non-infected mites and are more informative than the mean fecundities.

Toxoplasma gondii: Effect of maternal infection in the development of lymphoid organs of BALB/c neonates

Toxoplasmosis is one of the worldwide parasitic zoonoses. Alterations in the lymphopoietic system are still poorly studied. We analyzed lymphoid organs of BALB/c mice neonates from Toxoplasma gondii-intraperitoneally-infected mothers on 19th day of gestation, with 30 tachyzoites of strain RH. Normal non-infected pregnant females were used as controls. At 7 days after birth, animals were classified as neonates from infected (NIM) and neonates from non-infected mothers (NNIM). Weight of the thymus and number of thymic cells in NIM were decreased, percentage of apoptosis was significantly increased. Decrease in lymphocytes and monocytes and an increase of plasma cells were observed in bone marrow of NIM. Peripheral blood of NIM showed an increase of monocytes and neutrophils and a decrease in lymphocytes. Infection of the mother during the last day of gestation provokes in the neonates changes in the lymphoid organs that could explain survival of 75% of them.