RESUMO
Canine distemper virus (CDV) is a highly contagious pathogen for domestic dogs and several wild carnivore species. In Brazil, natural infection of CDV in dogs is very high due to the large non-vaccinated dog population, a scenario that calls for new studies on the molecular epidemiology. This study investigates the phylodynamics and amino-acid signatures of CDV epidemic in South America by analyzing a large dataset compiled from publicly available sequences and also by collecting new samples from Brazil. A population of 175 dogs with canine distemper (CD) signs was sampled, from which 89 were positive for CDV, generating 42 new CDV sequences. Phylogenetic analysis of the new and publicly available sequences revealed that Brazilian sequences mainly clustered in South America 1 (SA1) clade, which has its origin estimated to the late 1980's. The reconstruction of the demographic history in SA1 clade showed an epidemic expanding until the recent years, doubling in size every nine years. SA1 clade epidemic distinguished from the world CDV epidemic by the emergence of the R580Q strain, a very rare and potentially detrimental substitution in the viral genome. The R580Q substitution was estimated to have happened in one single evolutionary step in the epidemic history in SA1 clade, emerging shortly after introduction to the continent. Moreover, a high prevalence (11.9%) of the Y549H mutation was observed among the domestic dogs sampled here. This finding was associated (p<0.05) with outcome-death and higher frequency in mixed-breed dogs, the later being an indicator of a continuous exchange of CDV strains circulating among wild carnivores and domestic dogs. The results reported here highlight the diversity of the worldwide CDV epidemic and reveal local features that can be valuable for combating the disease.
Assuntos
Vírus da Cinomose Canina/genética , Cinomose/epidemiologia , Epidemias , Hemaglutininas Virais/genética , Filogenia , RNA Viral/genética , Substituição de Aminoácidos , Animais , Teorema de Bayes , Brasil/epidemiologia , Cinomose/transmissão , Cinomose/virologia , Vírus da Cinomose Canina/classificação , Vírus da Cinomose Canina/isolamento & purificação , Cães , Feminino , Masculino , Epidemiologia Molecular , MutaçãoRESUMO
Bovine spongiform encephalopathy (BSE) is a transmissible fatal neurodegenerative disorder, presenting a characteristic spongiform degeneration of cattle brain due to the accumulation of a pathogenic and protease-resistant infectious protein (prion). Two deletion/insertion polymorphisms of the prion protein gene (23 bp at the promoter region and 12 bp at intron 1) were analyzed in three beef cattle herds (Aberdeen Angus, Charolais, and Franqueiro) to verify allele frequencies for possible use in selection of resistant animals. High frequencies of susceptibility alleles (23 and 12 bp deletion) and haplotype (23 del/12 del) were observed in the Aberdeen Angus and Charolais herds, but Franqueiro presented one of the highest frequencies of resistant alleles so far described. These data indicate the need for selection in Aberdeen Angus and Charolais breeds to increase the frequency of resistant animals in order to reduce the probabilities of BSE outbreaks in these populations.
Assuntos
Bovinos/genética , Encefalopatia Espongiforme Bovina/genética , Frequência do Gene , Predisposição Genética para Doença , Príons/genética , Animais , Sequência de Bases/genética , Encéfalo/metabolismo , Encéfalo/patologia , Brasil , Cruzamento , Bovinos/metabolismo , Surtos de Doenças/prevenção & controle , Encefalopatia Espongiforme Bovina/epidemiologia , Encefalopatia Espongiforme Bovina/metabolismo , Encefalopatia Espongiforme Bovina/patologia , Haplótipos , Íntrons/genética , Polimorfismo Genético , Príons/metabolismo , Regiões Promotoras Genéticas/genética , Deleção de Sequência/genéticaRESUMO
The genetic diversity of a single nucleotide polymorphism (SNP) at the exon 20 (T945M) of the leptin receptor gene (LEPR) and of three short tandem repeats (STRs BM7225, BMS694, and BMS2145) linked to LEPR was investigated in three beef cattle herds (Brangus Ibagé, Charolais, and Aberdeen Angus). A cheap and effective new method to analyze the T945M polymorphism in cattle populations was developed and the possible role of these polymorphisms in reproduction and weight gain of postpartum cows was evaluated. High levels of genetic diversity were observed with the average heterozygosity of STRs ranging from 0.71 to 0.81. No significant association was detected between LEPR markers and reproductive parameters or daily weight gain. These negative results suggest that the LEPR gene polymorphisms, at least those herein described, do not influence postpartum cows production.