Immunity in Haematophagous Insect Vectors of Parasitic Infection

Ham, P. J.

doi:10.1007/978-1-4612-2910-0_4

Cited by 26 publications

(27 citation statements)

References 146 publications

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“…These findings indicate the possibility that serine proteases may not be involved in the proPO-activating system in this insect (Gomes & Azambuja, unpublished results). Alternately, Ham (1992) observed that besides an active serine protease, a cysteine protease was strongly induced following trauma or infection with Onchocerca microfilariae in the haemolymph of Simulium ornatum. Since serine proteases are involved in the activation of proPO system, it was postulated that proteases present in S. ornatum haemolymph may not be restricted to triggering proPO activation, but may be responsible for the direct killing of microfilariae (Ham 1992).…”

Section: Discussionmentioning

confidence: 99%

“…Alternately, Ham (1992) observed that besides an active serine protease, a cysteine protease was strongly induced following trauma or infection with Onchocerca microfilariae in the haemolymph of Simulium ornatum. Since serine proteases are involved in the activation of proPO system, it was postulated that proteases present in S. ornatum haemolymph may not be restricted to triggering proPO activation, but may be responsible for the direct killing of microfilariae (Ham 1992). However, this hypothesis is not adequate for T. rangeli infection due to the fact that protease does not kill the parasite, by contrary it survives and develops in Rhodnius haemolymph (Mello et al 1995, Gomes et al 1999.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus

Feder¹,

Gomes²,

Garcia³

et al. 1999

Mem. Inst. Oswaldo Cruz

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus

Feder¹,

Gomes²,

Garcia³

et al. 1999

Mem. Inst. Oswaldo Cruz

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“…Among the factors that can affect the survival and development of the parasites within the vector are (1) genetically determined host susceptibility or refractoriness to infection (Curtis & Graves, 1983), (2) the damage caused to ingested parasites by the cibarial/buccopharyngeal armature of the flies when it is present (Coluzzi & Trabucchi, 1968;Omar & Garms, 1975;McGreevy et al 1978;Reid, 1978Reid, , 1994, (3) the dynamics of formation and structure of the peritrophic membrane, secreted around the bloodmeal (Lewis, 1950(Lewis, , 1953Duke & Lewis, 1964;Reid & Lehane, 1984;Miller & Lehane, 1993) and (4) the mounting of specific and non-specific insect defences to parasite invasion (Townson & Chaithong, 1991;Ham, 1992). Some or all of these factors may be influenced by the density of the corresponding parasite stages.…”

Section: G Basanez and Othersmentioning

confidence: 99%

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

et al. 1995

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SUMMARYA previous paper reported that the intake of Onchocerca volvulus microfilariae (mff) by different species of Simulium is essentially proportional to the parasite load in the skin of infected carriers. This paper examines the fate of the ingested mff in susceptible vectors to assess the relationship between parasite intake and infective larval output in blackfly species with and without well-developed cibarial armatures. Analysis is based on data from 3 onchocerciasis endemic areas: /S. sirbanum) and the Amazonian focus between South Venezuela and Northern Brazil (S. guianense and S. oyapockense s.L).The data, which include published and unedited information collected in the field, record experimental studies of parasite uptake by wild flies maintained in captivity until the completion of the extrinsic incubation period. The relationship between L3 output (measured as the mean number of successful larvae/fly or, as the proportion of flies with infective larvae) and average microfilarial intake, was strongly non-linear. This non-linearity was best represented by a sigmoid function in case of armed simuliids (S. ochraceum s.L, S. oyapockense s.L), or by a hyperbolic expression in that of unarmed flies (S. damnosum s.L, S. guianense). These results are compatible, respectively, with the patterns of 'initial facilitation' and 'limitation' described in culicid vectors of lymphatic filariases. A maximum mean number of 1-3 L3/fly was observed in all 4 vectors. It is concluded that O. volvulus larval development to the infective stage is regulated by density-dependent mechanisms acting at the early phase of microfilarial migration out of the blackfly's bloodmeal. Damage by the bucco-pharyngeal armature may also be density dependent. A hypothesis, based on this density dependence is forwarded to explain initial facilitation, so far only recorded in vectors with well-developed cibarial teeth. Our results provide quantitative support for the conjecture that chemotherapy alone is likely to have a greater impact on reducing onchocerciasis transmission in endemic areas where the main vector has a toothed fore-gut than in foci where the vectors have unarmed cibaria.

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“…comm.). Other defense molecules such as inducible haemolymph proteases are also known in blackflies (Ham, 1992). A number of these are activated in response to infection, and comprise both serine and cysteine type species.…”

Section: Humoral Defense Moleculesmentioning

confidence: 99%

“…There is now a considerable body of data describing the innate and acquired resistance of vectors to the para sites they carry (eg. reviewed by Townson and Chaithong, 1993 ;Christensen and Severson 1993 ;Ham, 1992). Blackflies and mosquitoes possess complex immune sys tems, comprising inter-related cellular and humoral compo nents.…”

Section: Introductionmentioning

confidence: 99%

Humoral defense molecules in vectors of filariasis

et al. 1994

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VECTOR BIOLOGYPolyamine analogues, e.g. fc^XbenzyDpolyamine (MDL 27695), although shown to interfere strongly with both polyamine uptake systems of filarial worms, probably exhi bit their filaricidal effects by competing and interacting with polyamine binding sites such as nucleic acids and structural macromolecules.Inhibition of S-adenosylmethionine decarboxylase, a regula tory and rate-limiting step in the biosynthesis of polyamines which provides the aminopropyl group for the synthesis of spermidine and spermine, results in depletion of poly amines. MDL 73811, an irreversible inhibitor of S-adenosyl methionine decarboxylase, affects both polyamine synthesis and the viability of nematodes maintained in vitro.The strategy proposed here is directed to the interconversion and degradation pathway for polyamines. This is based on the findings that the polyamine oxidase is the rate-limiting step for the back conversion of spermine to spermidine and putrescine and that elevated levels of sper mine are lethal for Brugia worms maintained in vitro. The potential of polyamine oxidase as a target for chemothe rapy has been assessed by treatment of Brugia and Ascaris worms with MDL 72145, an irreversible inhibitor of nema TODE polyamine oxidase, which resulted in enzyme inactivation and a subsequent accumulation of spermine. By structural analysis of the filarial polyamine oxidase and the isofunctional mammalian enzyme, differences may be iden tified and exploited for the synthesis of drugs which react selectively with the parasite enzyme.

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Immunity in Haematophagous Insect Vectors of Parasitic Infection

Cited by 26 publications

References 146 publications

Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus

Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

Humoral defense molecules in vectors of filariasis

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