Identification of Novel Genes and Proteoforms in Angiostrongylus costaricensis through a Proteogenomic Approach.

RNA sequencing (RNA-Seq) and mass-spectrometry-based proteomics data are often integrated in proteogenomic studies to assist in the prediction of eukaryote genome features, such as genes, splicing, single-nucleotide (SNVs), and single-amino-acid variants (SAAVs). Most genomes of parasite nematodes are draft versions that lack transcript- and protein-level information and whose gene annotations rely only on computational predictions. Angiostrongylus costaricensis is a roundworm species that causes an intestinal inflammatory disease, known as abdominal angiostrongyliasis (AA). Currently, there is no drug available that acts directly on this parasite, mostly due to the sparse understanding of its molecular characteristics. The available genome of A. costaricensis, specific to the Costa Rica strain, is a draft version that is not supported by transcript- or protein-level evidence. This study used RNA-Seq and MS/MS data to perform an in-depth annotation of the A. costaricensis genome. Our prediction improved the reference annotation with (a) novel coding and non-coding genes; (b) pieces of evidence of alternative splicing generating new proteoforms; and (c) a list of SNVs between the Brazilian (Crissiumal) and the Costa Rica strain. To the best of our knowledge, this is the first time that a multi-omics approach has been used to improve the genome annotation of A. costaricensis. We hope this improved genome annotation can assist in the future development of drugs, kits, and vaccines to treat, diagnose, and prevent AA caused by either the Brazil strain (Crissiumal) or the Costa Rica strain.

Proteolytic activity in the adult and larval stages of the human roundworm parasite Angiostrongylus costaricensis.

Angiostrongylus costaricensis is a nematode that causes abdominal angiostrongyliasis, a widespread human parasitism in Latin America. This study aimed to characterize the protease profiles of different developmental stages of this helminth. First-stage larvae (L1) were obtained from the faeces of infected Sigmodon hispidus rodents and third-stage larvae (L3) were collected from mollusks Biomphalaria glabrata previously infected with L1. Adult worms were recovered from rodent mesenteric arteries. Protein extraction was performed after repeated freeze-thaw cycles followed by maceration of the nematodes in 40 mM Tris base. Proteolysis of gelatin was observed by zymography and found only in the larval stages. In L3, the gelatinolytic activity was effectively inhibited by orthophenanthroline, indicating the involvement of metalloproteases. The mechanistic class of the gelatinases from L1 could not be precisely determined using traditional class-specific inhibitors. Adult worm extracts were able to hydrolyze haemoglobin in solution, although no activity was observed by zymography. This haemoglobinolytic activity was ascribed to aspartic proteases following its effective inhibition by pepstatin, which also inhibited the haemoglobinolytic activity of L1 and L3 extracts. The characterization of protease expression throughout the A. costaricensis life cycle may reveal key factors influencing the process of parasitic infection and thus foster our understanding of the disease pathogenesis.

Proteolytic activity in the adult and larval stages of the human roundworm parasite Angiostrongylus costaricensis

Angiostrongylus costaricensis is a nematode that causes abdominal angiostrongyliasis, a widespread human parasitism in Latin America. This study aimed to characterize the protease profiles of different developmental stages of this helminth. First-stage larvae (L1) were obtained from the faeces of infected Sigmodon hispidus rodents and third-stage larvae (L3) were collected from mollusks Biomphalaria glabrata previously infected with L1. Adult worms were recovered from rodent mesenteric arteries. Protein extraction was performed after repeated freeze-thaw cycles followed by maceration of the nematodes in 40 mM Tris base. Proteolysis of gelatin was observed by zymography and found only in the larval stages. In L3, the gelatinolytic activity was effectively inhibited by orthophenanthroline, indicating the involvement of metalloproteases. The mechanistic class of the gelatinases from L1 could not be precisely determined using traditional class-specific inhibitors. Adult worm extracts were able to hydrolyze haemoglobin in solution, although no activity was observed by zymography. This haemoglobinolytic activity was ascribed to aspartic proteases following its effective inhibition by pepstatin, which also inhibited the haemoglobinolytic activity of L1 and L3 extracts. The characterization of protease expression throughout the A. costaricensis life cycle may reveal key factors influencing the process of parasitic infection and thus foster our understanding of the disease pathogenesis.

Leishmania (Viannia) braziliensis: influence of successive in vitro cultivation on the expression of promastigote proteinases.

Cysteine proteinases are an important virulence factor in Leishmania parasites. In this study we analyzed the cysteine proteinase expression of infective Leishmania (Viannia) braziliensis promastigotes, examining the expression induced by successive in vitro passages in culture. We observed that this parasite presents a decrease in its virulence over BALB/c macrophages, after successive passages in culture, but still they present proteinase activity, being capable of hydrolyzing the substrate pGlu-Phe-Leu-p Nitroanilide at pH 7.0. This proteinase activity also decreases in the course of the successive passages. Additionally, the decrease in the amount of CPB proteins following successive passages of promastigotes was verified by immunoblotting assays, using an anti-CPB antiserum. Real-time PCR assays were performed to assess the relative cpb expression when compared to a housekeeping gene in promastigote cDNA preparations from the first, fourth and seventh passages. Interestingly, the data indicate a relative increase in cpb gene transcripts as the promastigotes were maintained under in vitro culture: 2.2 times higher for fourth and 2.7 times higher for seventh passages when compared to the first passage. Thus, the information gathered here shows that the expression of cysteine proteinases is modified during in vitro cultivation of L. (V.) braziliensis promastigotes.

Cisteína-proteinases em promastigotas de Leishmania (Viannia) braziliensis / Cysteine-proteinases in promastigotes of Leishmania (Viannia) braziliensis

No presente trabalho foram detectadas cisteína-proteinases (CPs) em promastigotas infectivas de Leishmania (Viannia) braziliensis. A estratégia de purificação consistiu na associação do método de extração por Triton X-114 com cromatografia em coluna de Concanavalina A-Sepharose, seguida por outra de DEAE-Sephacel. No ensaio das cromatografias, observamos um picomajoritário de atividade enzimática na presença do substrato pEFLpNan (165 x 10 (elevado a -32) (miu)M de pNan/minuto) para cerca de 10(elevado a 10) parasitas, coincidente com o pico majoritário da proteína eluído da coluna de troca iônica. A análise por SDS-PAGE do material eluído da coluna de troca iônica mostrou quatro principais bandas de proteínas com massas moleculares relativas de 63, 43, 30 e 27kDa. Os ensaios da atividade enzimática após eletroforese mostraram que as bandas de 63 kDa e 43 kDa, hidrolisam substratos como gelatina em pH 7,0 e são sensíveis de E-64. Além disso, as duas enzimas são capazes de hidrolisar o substrato pEFLpNan: 63 kDa (2,2(mais ou menos) 0,3(miu)M de pNan/minuto) e 43 kDa (0,05(mais ou menos) 0,2(miu)M de pNan/minuto), e são inibidas por 10(miu)M E-64 (47por cento e 36por cento, respectivamente). Os ensaios de reconhecimento imunológico utilizando um anti-soro policlonal específico contra cisteína-proteinase B [anti-CPB de L. (L.) mexicana] revelaram que as enzimas de 63 kDa e 43kDa são reconhecidas por este anti-soro. Os experimentos de aglutinação, citometria de fluxo e imunocitoquímica utilizando esse mesmo antisoro revelaram que homólogos de CPBs estão localizados na superfície da membrana de promastigotas. Além disso, a incubação dos promastigotas com fosfolipase C (PLC) reduziu o número de células positivas para os homólogos de CPB. Os anti-soros anti-CRD (cross reactive determinat) e anti-CPB reconhecem bandas de 63 kDa e 43 kDa do sobrenadante das células tratadas com PLC em ensaios de immunoblotting sugerindo que isoformas destas...intracelulares.