Serological evidence of Borrelia circulation among blood donors in the São Paulo state, Brazil.

OBJECTIVE: The objective of this study was to examine the Borrelia seroprevalence among blood donors in Southeast Brazil. BACKGROUND: There is evidence that Borrelia spirochetes are circulating in Brazil; however, there are no studies that characterise these bacteria and investigate their seroprevalence in the Brazilian population. Such a situation, combined with a recent outbreak of tick-borne Rocky Mountain spotted fever in the São Paulo state demonstrates the increasing role of ticks as arthropod vectors in Brazil. METHODS: For the purpose of the study, 452 blood donors from Ribeirão Preto city, São Paulo state were tested using anti-Borrelia immunoglobulin G (IgG) assay. The positive results were also confirmed by Western blot for anti-borrelia IgM/IgG. RESULTS: The anti-Borrelia IgG enzyme-linked immunosorbent assay (ELISA) showed nine positive and nine borderline reactive samples, giving a total seroprevalence of 2·0% of anti-Borrelia IgG among Brazilian blood donors. The confirmation of the seropositive and borderline samples by Borrelia Western blot was demonstrated by IgG-positive results in 16 samples (a seroprevalence of 3.5%). Anti-Borrelia IgM antibodies were also detected in one sample. CONCLUSIONS: Our results demonstrate that Borrelia-like spirochetes may be circulating among blood donors from the São Paulo State and that the ticks have an important epidemiological role as vectors of bacterial infections in this Brazilian region. These results not only alert us to possible actions that might be undertaken in order to completely characterise the aetiological agents of Lyme-like syndromes in Brazil but also the possible impact that these bacterial agents might have on haemotherapy practices.

Human pegivirus-1 (HPgV-1) RNA prevalence and genotypes in volunteer blood donors from the Brazilian Amazon.

OBJECTIVES: The objectives of this study were to evaluate the prevalence of Human Pegivirus-1 (HPgV-1) viremia and genotype diversity among healthy blood donors from the Eastern Brazilian Amazon (city of Macapá, State of Amapá). There is little information for prevalence and circulation of HPgV-1 in this remote Brazilian region. MATERIALS AND METHODS: We conducted a study evaluating the HPgV-1 RNA prevalence and circulating genotypes in 431 volunteer blood donors originating from the Eastern Brazilian Amazon. The obtained HPgV-1 positive samples were submitted to sequencing and genotyping analysis in order to examine the genotype diversity of this virus in the Brazilian Amazon. RESULTS: Our results demonstrated a prevalence of HPgV-1 RNA in 9.5% of the tested blood donors. The phylogenetic analyses of the detected positive samples showed the presence of HPgV-1 genotypes 1, 2 and 3. The most frequently detected genotype was 2 (78.0% of the cases) represented by sub-genotypes 2A (39.0%) and 2B (39.0%). At lower rates, genotypes 1 (14.6%) and 3 (7.4%) were also detected. CONCLUSION: Our results revealed the presence of genotypes with European, Asiatic and African endemicity in Amazonian blood donors, probably due to the complex miscegenation processes that took place in this Brazilian region. More investigations, including information for the prevalence of HPgV-1 RNA in blood donors from other Latin American countries are needed to estimate the viremic rates and genotype distribution of this virus in a highly diverse continent like South America.

Phagocytosis by macrophages mediated by receptors for denatured proteins - dependence on tyrosine protein kinases.

Previous studies have demonstrated that some components of the leukocyte cell membrane, CR3 (Mac-1, CD11b/CD18) and p150/95, are able to bind to denatured proteins. Thus, it is of interest to know which effector functions of these cells can be triggered by these receptors when they interact with particles or surfaces covered with denatured proteins. In the present study we analyzed their possible role as mediators of phagocytosis of red cells covered with denatured bovine serum albumin (BSA) by mouse peritoneal macrophages. We observed that a) macrophages are able to recognize (bind to) these red cells, b) this interaction can be inhibited by denatured BSA in the fluid phase, c) there is no phagocytosis of these particles by normal macrophages, d) phagocytosis mediated by denatured BSA can be, however, effectively triggered in inflammatory macrophages induced by glycogen or in macrophages activated in vivo with LPS, and e) this phagocytic capacity is strongly dependent on the activity of tyrosine protein kinases in its signal transduction pathway, as demonstrated by using three kinds of enzyme inhibitors (genistein, quercetin and herbimycin A).

Phagocytosis by macrophages mediated by receptors for denatured proteins - dependence on tyrosine protein kinases

Previous studies have demonstrated that some components of the leukocyte cell membrane, CR3 (Mac-1, CD11b/CD18) and p150/95, are able to bind to denatured proteins. Thus, it is of interest to know which effector functions of these cells can be triggered by these receptors when they interact with particles or surfaces covered with denatured proteins. In the present study we analyzed their possible role as mediators of phagocytosis of red cells covered with denatured bovine serum albumin (BSA) by mouse peritoneal macrophages. We observed that a) macrophages are able to recognize (bind to) these red cells, b) this interaction can be inhibited by denatured BSA in the fluid phase, c) there is no phagocytosis of these particles by normal macrophages, d) phagocytosis mediated by denatured BSA can be, however, effectively triggered in inflammatory macrophages induced by glycogen or in macrophages activated in vivo with LPS, and e) this phagocytic capacity is strongly dependent on the activity of tyrosine protein kinases in its signal transduction pathway, as demonstrated by using three kinds of enzyme inhibitors (genistein, quercetin and herbimycin A)