Stage- and Gender-Specific Proteomic Analysis of Brugia malayi Excretory-Secretory Products

To succeed in infection, parasites must have ways to reach the host, penetrate its tissues and escape its defense systems. As they are not necessarily fatal, most helminth parasites remain viable within their host for many years, exerting a strong influence over the host immune function. Many of these functions are performed by products that are released from the parasite. We exploited the remarkable sensitivity of modern proteomics tools together with the availability of a sequenced genome to identify and compare the proteins released in vitro by adult males, adult females and the microfilariae of the filarial nematode Brugia malayi. This parasite is one of the etiological agents of lymphatic filariasis, a disease that poses continuing and significant threats to human health. The different forms of the parasite inhabit different compartments in the mammalian host. We found that the set of proteins released by each form is unique; they must reflect particular developmental processes and different strategies for evasion of host responses. The identification of these proteins will allow us to illuminate the biology of secretory processes in this organism and to establish a path for developing an understanding of how these parasite proteins function in immune evasion events

The bacterial catalase from filarial DNA preparations derives from common pseudomonad contaminants and not from Wolbachia endosymbionts

Wolbachia are obligatory endosymbionts in many species of filarial nematodes. Certain bacterial molecules induce antibody responses in mammalian hosts infected with filariae, while others activate inflammatory responses that contribute to pathology. These findings, coupled with antibiotic studies demonstrating the dependence of filarial embryogenesis on the presence of Wolbachia, have intensified research on Wolbachia-nematode interactions, and the effects of Wolbachia molecules on the mammalian immune system. By amplification and sequencing of 16S rDNA and catalase sequences, we show that filarial DNA samples prepared from nematodes collected under typical conditions are frequently contaminated with Pseudomonas DNA. Analysis of a published DNA fragment containing a catalase attributed to the Wolbachia of Onchocerca volvulus showed it to be most like Pseudomonas, both in terms of sequence similarity and genomic organization. Additionally, there was no obvious catalase in either of two available Wolbachia genome sequences. Contamination of filarial DNA with bacterial sequences other than Wolbachia can complicate studies of the role of these symbionts in filarial biology

Effect of Cysticercus cellulosae fractions on the respiratory burst of pig neutrophils Efeito de frações de Cysticercus cellulosae sobre a explosão respiratória de neutrófilos de suínos

Neutrophils, eosinophils and macrophages are cells that interact with invading parasites and naive hosts have been shown to have anti-parasitic activity. The initial reaction of these leukocytes is the generation of reactive oxygen species (ROS) to play in parasite expulsion. The present work was carried out to study the effect of total extract, scolex and membrane fractions from Cysticercus cellulosae on respiratory burst by pig neutrophils. Hydrogen peroxide (H2O2) production by neutrophils incubated with metacestode fractions from C. cellulosae showed an increase of: 190% (total extract), 120% (scolex) and 44% (membrane). High antioxidant catalatic activity (33%, 28%, 28% by total extract, scolex and membrane, respectively) was observed in neutrophils incubated with metacestode fractions, which could be an attempt at self-protection. Scolex and membrane fractions increased the phagocytic capacity of neutrophils (44% and 28%, respectively). On the other hand, total cysticerci did not alter the phagocytosis, possibly due to modifications in membrane function, caused by high ROS production from neutrophils in the presence of total cysticerci. Total fraction from C. cellulosae is toxic for neutrophils as shown by the decrease in phagocytic capacity, probably caused by high levels of ROS formation. The difference in toxicity of total extract, scolex and membrane fractions on neutrophils can be explained by the presence of an antigenic effect of the vesicular fluid in the total extract of C. cellulosae.<br>Neutrófilos, eosinófilos e macrófagos são células que interagem com os parasitas no corpo do hospedeiro desenvolvendo atividade antiparasitária. A reação inicial destes leucócitos é a geração de espécies reativas de oxigênio (ERO) a fim de expulsar os parasitas. No presente trabalho estudou-se o efeito da fração total, de escolex e de membrana de Cysticercus cellulosae sobre a explosão respiratória de neutrófilos de suínos. A produção de peróxido de hidrogênio (H2O2) pelos neutrófilos incubados com as frações de C. cellulosae apresentou acréscimo de 190% (extrato total), 120% (escolex) e 44% (membrana). Alta atividade de catalase (33%, 28% e 28% para extrato total, escolex e membrana respectivamente) foi observada nos neutrófilos incubados com as frações de metacestodeo, podendo representar a própria proteção celular do neutrófilo. Frações de escolex e de membrana aumentaram a capacidade fagocitária dos neutrófilos (44% e 28%, respectivamente). Por outro lado, a fração total do cisticerco não alterou a capacidade fagocitária dos neutrófilos, o que pode estar relacionada com modificações na função da membrana celular causadas pela alta produção de ERO na presença da fração total. O extrato total de C. cellulosae é tóxico para os neutrófilos, indicada pela diminuição da capacidade fagocitária, provavelmente pela indução de alto nível de ERO. A diferença de toxicidade do extrato total, de escolex e de membrana para os neutrófilos pode ocorrer pelo efeito antigênico presente no fluido vesicular no extrato total de C. cellulosae