Preliminary characterization of a Rhodnius prolixus hemolymph trypanolytic protein, this being a determinant of Trypanosoma rangeli KP1(+) and KP1(-) subpopulations' vectorial ability

Abstract

Rhodnius prolixus is the main Trypanosoma rangeli vector in several Latin-American countries and is susceptible to infection with KP1(+) strains; however, it presents an invasion-resistant response to KP1(-) strains. The present work has identified a trypanolytic protein against T. rangeli KP1(-) in the R. prolixus hemolymph which was fractioned with ammonium sulfate (following dialysis). The results revealed a protein component which did not depend on divalent cations for its biological function whilst keeping its trypanolytic activity at temperatures ranging from -20ºC to 37ºC, at 7.0 to 10.5 pH. The protein was partially purified by gel filtration chromatography and ionic exchange chromatography. The major component presented a molecular weight of around 79 kDa and an isoelectric point between 4.9 and 6.3 and may be directly related to hemolymph trypanolytic activity against T. rangeli KP1(-) populations.Key words: Rhodnius prolixus -Trypanosoma rangeli KP1(+) -Trypanosoma rangeli KP1(-) -trypanolytic factorvectorial ability -insect immunity Trypanosoma rangeli is a hemoflagellate which is apparently apathogenous for humans, presenting pathogenicity for the invertebrate host. T. rangeli is of great interest due to its presence in mixed infection with Trypanosoma cruzi in vertebrates and invertebrate hosts, thereby interfering with a clear diagnosis of Chagas' disease and the epidemiology of these parasites in different Latin-American countries .T. rangeli vectors become infected by ingesting blood from wild or domestic reservoirs in natural conditions. The parasite develops in the digestive tract and then invades the hemolymph where it is recognized by the vector's immune system; however, some strains may escape host defense mechanisms, reaching the salivary glands where they become infective forms or metacyclic trypomastigotes (D'Alessandro-Bacigalupo & Gore-Saravia 1992). Salivary gland invasion is a necessary step for transmission, being mediated by one or several ligandreceptor interactions (Basseri et al. 2002).Previous work has revealed two phylogenetically different groups in T. rangeli called T. rangeli KP1(-) and T. rangeli KP1(+), these being mainly transmitted by the 16 Rhodnius species described so far (Vallejo et al. 2002(Vallejo et al. , 2007. Specificity between the vector and the parasite strain which it transmits has been pointed out; each Rhodnius species seems to select the T. rangeli subpopulation to which it is susceptible in nature so that it can then be transmitted to the vertebrate host via insect bite . Nevertheless, a close association has been observed between T. rangeli KP1(+) and vectors from the prolixus group (which includes Rhodnius prolixus and Rhodnius neglectus) and between T. rangeli KP1(-) and vectors from the pallescens group (including Rhodnius pallescens, Rhodnius colombiensis and Rhodnius ecuadoriensis) , Urrea et al. 2005. Recent parasite-vector interaction studies have shown a trypanolytic factor in R. prolixus hemolymph impeding the development of T. rangeli KP1(...

Susceptibilidad de diferentes especies de Rhodnius (Hemiptera, Reduviidae, Triatominae) a una cepa brasileña de Trypanosoma rangeli (SC58/KP1-)

“…and a hypothesis that these triatomines act as biological filters in the transmission of genetically distinct populations of T. rangeli (11,14,15 (11). Such association agrees with the report of a trypanolytic protein present in R. prolixus hemolymph, which selectively lyses (KP1-) strains isolated from R. pallescens, R. colombiensis and R. ecuadoriensis, but not (KP1+) strains (18). However, the susceptibility of the species that give the name to these evolutionary lineages (R. pictipes and R. robustus) has not yet been evaluated.…”

Behavioral fever response in Rhodnius prolixus (Reduviidae: Triatominae) to intracoelomic inoculation of Trypanosoma cruzi

“…Conversely, T. rangeli always leaves the digestive tract to travel to the salivary glands and is transmitted through the bite of an infected individual (14) (17) . According to Zingales et al (18) , six groups of T. cruzi are recognized (T. cruzi I to VI), while for T. rangeli only two groups have been defi ned [T. rangeli KP1(-) and T. rangeli KP1(+)] (19) .…”

Genes de cisteíno proteases (Catepsina L-like) de Trypanosoma rangeli: polimorfismo, relações filogenéticas e alvos para diagnóstico e genotipagem.

“…lisozimas e atividade tripanolítica (MELLO et al, 1995;GOMES et al, 1999;PULIDO et al, 2008); ativação do sistema profenoloxidase (MELLO et al, 1995;GOMES et al, 1999GOMES et al, , 2003GARCIA et al, 2004); fagocitose e micro-aglutinação de hemócitos (MELLO et al, 1995;GARCIA et al, 2004) e a geração de radicais citotóxicos superóxido e óxido nítrico (WHITTEN et al, 2001AZAMBUJA et al, 2005, AZAMBUJA e GARCIA, 2005 AGUILAR et al, 2007).…”

“…Estudos anteriores baseados em marcadores do gene de mini-exon e em padrões de minicírculos de kDNA haviam revelado os grupos A e C (GRISARD et al, 1999a;VALLEJO et al, 2003;URREA et al, 2005 PULIDO et al, 2008;GOMES et al, 2003GOMES et al, , 2008.…”

“…No intestino e nas glândulas salivares do inseto existem lectinas que modulam a adesão do parasita, na hemolinfa, T. rangeli desencadeia a produção de enzimas e outros fatores tripanolíticos entre outros mecanismos de defesa imune humoral (AZAMBUJA et al, 2005;AZAMBUJA e GARCIA, 2005;PULIDO et al, 2008;GOMES et al, 2008). Entretanto na relação de T.rangeli com o vetor pouco é conhecido a cerca dos processos imunológicos que envolvem os radicais livres como superóxido (O2 ¯) e óxido nítrico ( NO), os quais também poderiam participar ativamente na interação parasita hospedeiro.…”