RESUMEN
Mosquito-borne flaviviruses (MBFVs) are of public and animal health concern because they cause millions of human deaths annually and impact domestic animals and wildlife globally. MBFVs are phylogenetically divided into two clades, one is transmitted by Aedes mosquitoes (Ae-MBFVs) associated with mammals and the other by Culex mosquitoes (Cx-MBFVs) associated with birds. However, this assumption has not been evaluated. Here, we synthesized 79 published reports of MBFVs from wild mammals, estimating their host. Then, we tested whether the host specificity was biased to sampling and investigation efforts or to phylogenetic relationships using a viral phylogenetic tree drawn from analyzing whole flavivirus genomes obtained in GenBank. We found in total 18 flaviviruses, nine related to Aedes spp. and nine to Culex spp. infecting 129 mammal species. Thus, this supports that vectors are transmitting MBFV across available host clades and that ornithophilic mosquitoes are readily infecting mammals. Although most of the mosquito species are generalists in their host-feeding preferences, we also found a certain degree of MBFV's specificity, as most of them infect closely related mammal species. The present study integrates knowledge regarding MBFVs, and it may help to understand their transmission dynamics between viruses, vectors, and mammal hosts.
Asunto(s)
Interacciones Microbiota-Huesped/inmunología , Especificidad del Huésped/genética , Especificidad del Huésped/inmunología , Mosquitos Vectores/virología , Fiebre del Nilo Occidental/inmunología , Fiebre del Nilo Occidental/transmisión , Virus del Nilo Occidental/aislamiento & purificación , Aedes/virología , Animales , Animales Domésticos/virología , Culex/virología , Interacciones Microbiota-Huesped/genética , Mamíferos/genética , Mamíferos/virologíaRESUMEN
In accordance with the Red Queen hypothesis, the lower genotypic diversity in clonally reproducing species should make them easier targets for pathogen infection, especially when closely related sexually reproducing species occur in close proximity. We analyzed two populations of clonal P. formosa and their sexual parental species P. mexicana by correlating individual parasite infection with overall and immune genotype. Our study revealed lower levels of overall genotypic diversity and marginally fewer MHC class I alleles in P. formosa individuals compared to sexually reproducing P. mexicana. Parasite load, however, differed only between field sites but not between species. We hypothesize that this might be due to slightly higher genotypic diversity in P. formosa at the innate immune system (toll like receptor 8) which is likely due to the species' hybrid origin. In consequence, it appears that clonal individuals do not necessarily suffer a disadvantage compared to sexual individuals when fighting parasite infection.
Asunto(s)
Poecilia/fisiología , Poecilia/parasitología , Reproducción Asexuada/genética , Reproducción Asexuada/inmunología , Inmunidad Adaptativa/genética , Alelos , Animales , Femenino , Proteínas de Peces/genética , Proteínas de Peces/inmunología , Genes MHC Clase I , Variación Genética , Genotipo , Especificidad del Huésped/genética , Especificidad del Huésped/inmunología , Inmunidad Innata/genética , Masculino , México , Modelos Genéticos , Modelos Inmunológicos , Carga de Parásitos , Poecilia/genética , Reproducción/genética , Reproducción/inmunología , Especificidad de la Especie , Receptor Toll-Like 8/genética , Receptor Toll-Like 8/inmunologíaRESUMEN
The description of cryptic species with different pathogenic potentials has changed the perspectives on sporotrichosis. Sporothrix schenckii causes a benign chronic subcutaneous mycosis, Sporothrix brasiliensis is highly virulent, and Sporothrix globosa mainly causes fixed cutaneous lesions. Furthermore, S. brasiliensis is the prevalent species related to cat-transmitted sporotrichosis. Sources of infection, transmission, and distribution patterns also differ between species, and variability differs between species because of different degrees of clonality. The present review article will cover several aspects of the biology of clinically relevant agents of sporotrichosis, including epidemiological aspects of emerging species. Genomic information of Sporothrix spp. is also discussed. The cell wall is an essential structure for cell viability, interaction with the environment, and the host immune cells and contains several macromolecules involved in virulence. Due to its importance, aspects of glycosylation and cell wall polysaccharides are reviewed. Recent genome data and bioinformatics analyses helped to identify specific enzymes of the biosynthetic glycosylation routes, with no homologs in mammalian cells, which can be putative targets for development of antifungal drugs. A diversity of molecular techniques is available for the recognition of the clinically relevant species of Sporothrix. Furthermore, antigens identified as diagnostic markers and putative vaccine candidates are described. Cell-mediated immunity plays a key role in controlling infection, but Sporothrix species differ in their interaction with the host. The adaptive branch of the immune response is essential for appropriate control of infection.
Asunto(s)
Sporothrix/fisiología , Esporotricosis/diagnóstico , Esporotricosis/inmunología , Animales , Antígenos Fúngicos/inmunología , Pared Celular/química , Pared Celular/metabolismo , Genoma Fúngico , Especificidad del Huésped/inmunología , Humanos , Técnicas de Diagnóstico Molecular , Sporothrix/clasificación , Sporothrix/inmunología , Esporotricosis/microbiología , Esporotricosis/transmisión , VirulenciaRESUMEN
Two trials were conducted to determine the prepatent and the patent period of Haemonchus contortus and Haemonchus placei in Santa Ines crossbred sheep and to determine whether serial infections with both species confer protection against homologous or heterologous challenge. To evaluate the prepatent and patent periods of infection, five lambs received a single infection with 4000 H. contortus-infective larvae (L3), and another five received a single infection with 4000 H. placei L3. H. contortus presented patency earlier than H. placei. Animals infected with both species shed a large number of eggs in the faeces for several months with the highest counts, with means higher than 3000 eggs per gram of faeces (EPG) between 24 and 106 days and between 38 and 73 days post infection with H. contortus and H. placei, respectively. H. contortus eggs were detected in the faeces for a minimum of 302 days and a maximum of 538 days post infection, while the H. placei patent period lasted from 288 to 364 days. In the second trial, one group of lambs (n=12) was serially infected 12 times (three times per week for four weeks) with 500 L3 of H. placei and then challenged with either H. placei (n=6) or with H. contortus (n=6). The lambs in the second group (n=12) were serially infected 12 times with 500 L3 of H. contortus and then challenged with H. contortus (n=6) or with H. placei (n=6), and a third group of lambs was single challenged with H. placei (n=6), H. contortus (n=6), or remained uninfected throughout the trial period (control group, n=6). Animals serially infected with H. placei and then challenged with the same species presented the most intense immune response with the highest levels of anti-parasitic immunoglobulin and number of inflammatory cells in the abomasal mucosa. As a result, this group had the lowest rate of parasite establishment (2.68% of the 4000 L3 given), but this phenomenon did not occur in animals single challenged with H. placei, in which the rate of establishment was relatively high (25.3%), confirming that the protective immune response to H. placei develops only when animals are repeatedly infected with this species. However, when the animals were previously serially infected with H. placei and then challenged with H. contortus, no evidence of significant protection was observed (establishment of 19.18%). The results of the trials showed an important role played by the immune response on parasite-host specificity.