RESUMEN
The development of plant-derived cysteine proteinases, such as those in papaya latex, as novel anthelmintics requires that the variables affecting efficacy be fully evaluated. Here, we conducted two experiments, the first to test for any effect of host sex and the second to determine whether the intensity of the worm burden carried by mice would influence efficacy. In both experiments, we used the standard C3H mouse reference strain in which papaya latex supernatant (PLS) consistently shows >80 % reduction in Heligmosomoides bakeri worm burdens, but to broaden the perspective, we also included for comparison mice of other strains that are known to respond more poorly to treatment with papaya latex. Our results confirmed that there is a strong genetic influence affecting efficacy of PLS in removing adult worm burdens. However, there was no effect of host sex on efficacy (C3H and NIH) and no effect of infection intensity (C3H and BALB/c). These results offer optimism that plant-derived cysteine proteinases (CPs), such as these from papaya latex, can function as effective anthelmintics, with neither host sex nor infection intensity presenting further hurdles to impede their development for future medicinal and veterinary usage.
Asunto(s)
Antihelmínticos/administración & dosificación , Carica/química , Proteasas de Cisteína/administración & dosificación , Látex/administración & dosificación , Nematospiroides/efectos de los fármacos , Extractos Vegetales/administración & dosificación , Proteínas de Plantas/administración & dosificación , Infecciones por Strongylida/tratamiento farmacológico , Animales , Antihelmínticos/química , Proteasas de Cisteína/química , Femenino , Látex/química , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Nematospiroides/fisiología , Extractos Vegetales/química , Proteínas de Plantas/química , Infecciones por Strongylida/parasitología , Resultado del TratamientoRESUMEN
Eight strains of mice, of contrasting genotypes, infected with Heligmosomoides bakeri were studied to determine whether the anthelmintic efficacy of papaya latex varied between inbred mouse strains and therefore whether there is an underlying genetic influence on the effectiveness of removing the intestinal nematode. Infected mice were treated with 330 nmol of crude papaya latex or with 240 nmol of papaya latex supernatant (PLS). Wide variation of response between different mouse strains was detected. Treatment was most effective in C3H (90·5-99·3% reduction in worm counts) and least effective in CD1 and BALB/c strains (36·0 and 40·5%, respectively). Cimetidine treatment did not improve anthelmintic efficacy of PLS in a poor drug responder mouse strain. Trypsin activity, pH and PLS activity did not differ significantly along the length of the gastro-intestinal (GI) tract between poor (BALB/c) and high (C3H) drug responder mouse strains. Our data indicate that there is a genetic component explaining between-mouse variation in the efficacy of a standard dose of PLS in removing worms, and therefore warrant some caution in developing this therapy for wider scale use in the livestock industry, and even in human medicine.
Asunto(s)
Antihelmínticos/farmacología , Carica/química , Proteasas de Cisteína/farmacología , Látex/farmacología , Proteínas de Plantas/farmacología , Enfermedades de los Roedores/genética , Infecciones por Strongylida/genética , Animales , Antihelmínticos/metabolismo , Carica/enzimología , Cimetidina/farmacología , Proteasas de Cisteína/metabolismo , Femenino , Tracto Gastrointestinal/efectos de los fármacos , Tracto Gastrointestinal/parasitología , Genotipo , Especificidad del Huésped , Concentración de Iones de Hidrógeno , Látex/metabolismo , Masculino , Ratones , Ratones Endogámicos , Nematospiroides/efectos de los fármacos , Nematospiroides/fisiología , Proteínas de Plantas/metabolismo , Enfermedades de los Roedores/tratamiento farmacológico , Enfermedades de los Roedores/parasitología , Especificidad de la Especie , Infecciones por Strongylida/tratamiento farmacológico , Infecciones por Strongylida/parasitologíaRESUMEN
The ability of animals to cope with an increasing parasite load, in terms of resilience and resistance, may be affected by both nutrient supply and demand. Here, we hypothesized that host nutrition and growth potential interact and influence the ability of mice to cope with different parasite doses. Mice selected for high (ROH) or low (ROL) body weight were fed a low (40 g/kg; LP) or high (230 g/kg; HP) protein diet and infected with 0, 50, 100, 150, 200 or 250 L3 infective Heligmosomoides bakeri larvae. ROH-LP mice grew less at doses of 150 L3 and above, whilst growth of ROH-HP and of ROL mice was not affected by infection pressure. Total worm burdens reached a plateau at doses of 150L3, whilst ROH mice excreted fewer worm eggs than ROL mice. Serum antibodies increased with infection dose and ROH mice were found to have higher parasite-specific IgG1 titres than ROL mice. In contrast, ROL had higher total IgE titres than ROH mice, only on HP diets. The interaction between host nutrition and growth potential appears to differentially affect resilience and resistance in mice. However, the results support the view that parasitism penalises performance in animals selected for higher growth.
Asunto(s)
Anticuerpos Antihelmínticos/sangre , Estado Nutricional/inmunología , Enfermedades de los Roedores/inmunología , Infecciones por Strongylida/inmunología , Animales , Peso Corporal , Cruzamientos Genéticos , Dieta , Proteínas en la Dieta/metabolismo , Ensayo de Inmunoadsorción Enzimática , Heces/parasitología , Inmunoglobulina E/sangre , Inmunoglobulina G/sangre , Larva/patogenicidad , Larva/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Nematospiroides/patogenicidad , Nematospiroides/fisiología , Recuento de Huevos de Parásitos , Carga de Parásitos , Enfermedades de los Roedores/sangre , Enfermedades de los Roedores/parasitología , Infecciones por Strongylida/sangre , Infecciones por Strongylida/parasitologíaRESUMEN
Nippostrongylus brasiliensis larvae are particularly susceptible to immunological attack during the pre-lung stage of primary and secondary infections in mice. Whilst most of the common laboratory strains of mice are permissive hosts for the parasite, in this study we report for the first time, the strong resistance of naive FVB/N mice to N. brasiliensis. Damage to larvae is evident within the first 24 h of infection and this may be critical to later larval development and reproductive success. Inflammatory responses in the skin, and larval escape from this tissue were comparable in susceptible CBA/Ca and resistant FVB/N mice, with most larvae exiting within 4 h of a primary infection. Lung larval burdens were also similar between strains, but larvae recovered from FVB/N mice were smaller and less motile. In FVB/N mice, larval colonization of the gut was impaired and worms produced very few eggs. However FVB/N mice did not show enhanced resistance to Heligmosomoides bakeri (also known as Heligmosomoides polygyrus), a nematode largely restricted to the gut. Damage done in the pre-lung or lung stages of infection with N. brasiliensis is likely to contribute to ongoing developmental and functional abnormalities, which are profoundly evident in the gut phase of infection.