Molecular variants of Leishmania (Viannia) braziliensis trigger distinct patterns of cytokines and chemokines expression in golden hamster.

Cutaneous leishmaniasis (CL) mainly caused by Leishmania braziliensis is a chronic inflammatory disease widely spread in Brazil. Genetic variant strains of this parasite have been associated with atypical clinical manifestations of CL in an endemic area in Brazil. Furthermore, these strains have presented distinct biological behaviors in golden hamster, suggesting differential activation of the immune response. In the present study we proposed to evaluate the localized immune response in golden hamsters infected with known molecular variant strains of L. braziliensis, in distinct time points post-infection (PI). Detailed analyses of the mRNA expression of cytokines and chemokines in hamster-skin lesions were performed. Heat map matrix and hierarchical cluster analysis were carried out to segregate the strains due to mRNA expression. Distinct patterns of immune response were found in both time points, more evident in the recent-phase disease (30 days-PI). At this time point, the genetic variant strains expressed high levels of tnfα, il12 and tgfß whilst the non-variant strain expressed ifnγ, il6, il4, il10, il13 and ccl17. The hierarchical clustering highlights this distinct pattern in which all genetic variant strain was grouped in the cluster I and the non-variant strain grouped into the cluster II. At late-phase disease (60 days-PI) all isolates expressed high levels of il4 and il10. The non-variant strain shown a significant reduced expression of ifnγ, il6, ccl17, and ccl22 whilst distinct patterns were observed for the genetic variant strains. For the first time, a large panel of cytokines and chemokines mRNA-expression was analyzed in experimental trials using golden hamsters as animal model and genetic variant strains of L. braziliensis. Our findings suggest that genetic variant strains of L. braziliensis are able to trigger differential gene expression of cytokines and chemokines in the skin lesion from infected hamsters. The parasite intrinsic ability to activate distinct pathways in the host-parasite interaction may be associated to the large spectrum of clinical manifestation observed in CL-patients.

Molecular epidemiology and evolution of avian infectious bronchitis virus

Mutation and recombination processes are involved in the genetic and phenotypic variations of RNA viruses, leading to the emergence of new variant strains, and give rise to virus population diversity to be modeled by the host, particularly by the immune system, as occurred with infectious bronchitis virus (IBV) in chickens. The consequence is a continuous emergence of new IBV variants with regard to pathotypes, serotypes, and protectotypes. Nucleotide sequencing and subsequent genetic analysis of the S1 and N protein gene sequences provide a fast and accurate method to classify and predict IBV genotype, and a powerful instrument to monitor phylogenetic and epidemiological evolution of IBV variants. Despite the use of vaccination programmes, infectious bronchitis has become a serious problem in Brazil. Thus, a significant number of IBV field variants have been identified circulating in the Brazilian commercial poultries between 2000 to 2006 and more recently in Argentina. These viruses seem to be indigenous, because they demonstrated a low genetic relatedness with the majority of the reference strains from North America, Europe and Asia, but were moderately to highly related one to another. In summary, indigenous field IBV variants were evolving and circulating in the field in Brazil and Argentina, and should be considered as initial candidates for protection against current IBV infectious in chickens. However, in vitro and in vivo studies are needed to determine the pathogenicity and immunogenecity of these new isolates, before defining a new vaccine strain.

Molecular epidemiology and evolution of avian infectious bronchitis virus

Mutation and recombination processes are involved in the genetic and phenotypic variations of RNA viruses, leading to the emergence of new variant strains, and give rise to virus population diversity to be modeled by the host, particularly by the immune system, as occurred with infectious bronchitis virus (IBV) in chickens. The consequence is a continuous emergence of new IBV variants with regard to pathotypes, serotypes, and protectotypes. Nucleotide sequencing and subsequent genetic analysis of the S1 and N protein gene sequences provide a fast and accurate method to classify and predict IBV genotype, and a powerful instrument to monitor phylogenetic and epidemiological evolution of IBV variants. Despite the use of vaccination programmes, infectious bronchitis has become a serious problem in Brazil. Thus, a significant number of IBV field variants have been identified circulating in the Brazilian commercial poultries between 2000 to 2006 and more recently in Argentina. These viruses seem to be indigenous, because they demonstrated a low genetic relatedness with the majority of the reference strains from North America, Europe and Asia, but were moderately to highly related one to another. In summary, indigenous field IBV variants were evolving and circulating in the field in Brazil and Argentina, and should be considered as initial candidates for protection against current IBV infectious in chickens. However, in vitro and in vivo studies are needed to determine the pathogenicity and immunogenecity of these new isolates, before defining a new vaccine strain.