In vitro culture of parasitic stages of Haemonchus contortus.

Haemonchus contortus is a constraint to sheep production. Seeking to reduce the use of hosts and produce parasitic stages in large-scale, a 42-day in vitro culture protocol of H. contortus third-stage larvae was optimized using Dulbecco's modified Eagle's medium (DMEM). In cell-free culture, larvae were maintained at 39.6°C, in acidic media (pH 6.1) for 3 or 6 days with Δ4-dafachronic acid followed by DMEM pH 7.4 supplemented or not with Fildes' reagent. In DMEM pH 7.4 at 37°C, supplementation with Caco-2 cells was compared to Fildes. On Day 14, fourth-stage larvae (L4) development rates in acidic media supplemented (86.8-88.4%) or not (74.4-77.8%) with Fildes and in Caco-2 cell co-culture (92.6%) were similar, and superior to DMEM pH 7.4 with Fildes (0.0%). On Day 21, Caco-2 cell co-culture resulted in higher larvae differentiation (25.0%) and lower degeneration (13.9%) compared to acidic media (1.5-8.1% and 48.6-69.9%, respectively). This is the first report of prolonged in vitro culture of H. contortus larvae using commercial media in co-culture with Caco-2 cells. Although no progression to the adult stage, Caco-2 cell co-culture resulted in morphological differentiation of H. contortus L4 and larval viability for up to 28 days.

In vitro culture of parasitic stages of Haemonchus contortus / Cultivo in vitro de estádios parasitários de Haemonchus contortus

Haemonchus contortus is a constraint to sheep production. Seeking to reduce the use of hosts and produce parasitic stages in large-scale, a 42-day in vitro culture protocol of H. contortus third-stage larvae was optimized using Dulbecco's modified Eagle's medium (DMEM). In cell-free culture, larvae were maintained at 39.6°C, in acidic media (pH 6.1) for 3 or 6 days with Δ4-dafachronic acid followed by DMEM pH 7.4 supplemented or not with Fildes' reagent. In DMEM pH 7.4 at 37°C, supplementation with Caco-2 cells was compared to Fildes. On Day 14, fourth-stage larvae (L4) development rates in acidic media supplemented (86.8-88.4%) or not (74.4-77.8%) with Fildes and in Caco-2 cell co-culture (92.6%) were similar, and superior to DMEM pH 7.4 with Fildes (0.0%). On Day 21, Caco-2 cell co-culture resulted in higher larvae differentiation (25.0%) and lower degeneration (13.9%) compared to acidic media (1.5-8.1% and 48.6-69.9%, respectively). This is the first report of prolonged in vitro culture of H. contortus larvae using commercial media in co-culture with Caco-2 cells. Although no progression to the adult stage, Caco-2 cell co-culture resulted in morphological differentiation of H. contortus L4 and larval viability for up to 28 days.(AU)

Haemonchus contortus provoca grandes prejuízos à ovinocultura. Visando reduzir a utilização de ovinos hospedeiros e produzir estágios parasitários em larga escala, um protocolo para o cultivo in vitro por 42 dias de larvas de terceiro estádio de H. contortus foi realizado em meio Eagle, modificado por Dulbecco (DMEM). No cultivo sem células, as larvas foram mantidas a 39,6°C e incubadas em DMEM ácido (pH 6,1) por 3 ou 6 dias com 4Δ-ácido dafacrônico seguido por DMEM pH 7,4 suplementado ou não com reagente de Fildes. Em DMEM pH 7,4 a 37°C, a suplementação com células Caco-2 foi comparada à suplementação com Fildes. No Dia 14, as taxas de desenvolvimento até o quarto estádio larvar (L4) foram similares em meio ácido sem células suplementado (86,8-88,4%) ou não (74,4-77,8%) com Fildes e em co-cultura com células Caco-2 (92,6%), e superiores ao desenvolvimento em DMEM pH 7,4 com Fildes (0,0%). No Dia 21, o co-cultivo com células Caco-2 resultou em maior diferenciação (25,0%) e menor degeneração (13,9%) das larvas em comparação ao meio ácido (1,5-8,1% e 48,6-69,9%, respectivamente). Este é o primeiro relato de cultivo in vitro prolongado de H. contortus em meio comercial em co-cultivo com células Caco-2. Apesar da ausência de progressão até o estágio adulto, o co-cultivo com células Caco-2 resultou em diferenciação de L4 e manutenção da viabilidade das larvas de H. contortus por até 28 dias in vitro.(AU)