Trichostrongylus colubriformis: in vitro culture of parasitic stages and their use for the evaluation of anthelmintics

The aggregation response of Trichostrongylus colubriformis: a basis for the rapid interpretation of in vitro anthelmintic screens

“…The medium was based on that developed previously for the culture of Nippostrongylus brasiliensis (Jenkins et al 1980;Jenkins & Carrington, 1982) and used also for the culture of Nematospiroides dubius and T. colubriformis (Rapson et al 1985).…”

“…All compounds were tested at least in duplicate at every concentration used. All drugs were evaluated at concentrations ranging by serial double dilution from a concentration at least 4 times greater than that known to inhibit the final moult of T. colubriformis in vitro (Rapson et al 1985), to one for which no inhibitory effects on the aggregation responses of the young adult worms was seen. The lowest dilution at which no worm aggregation was seen was regarded as the minimum inhibitory concentration (m.i.c.)…”

“…The parasitic late 4th-stage larvae of the nematodes, Nippostrongylus brasiliensis, Nematospiroides dubius and Trichostrongylus colubriformis are particularly susceptible in vitro to all major classes of the broad spectrum anti-trichostrongyle anthelmintics (Jenkins, Armitage & Carrington, 1980;Rapson, Jenkins & Topley, 1985). The activity of some, but not all of these compounds, is clearly discernible by their marked effects on the motility and/or survival of the worms in culture.…”

“…Such an in vitro screen employing worms of T. colubriformis (Rapson et al 1985) is particularly suitable for the preliminary identification of new potential broad-spectrum veterinary anthelmintics because it employs an actual target parasite of ruminants that can also be used in secondary in vivo assays, both in rodents (Ostlind & Cifelli, 1981) and of course in ruminants themselves. However, interpretation of the T. colubriformis in vitro screen, usually achieved by careful determination of the percentage of larval cuticles cast in the test wells relative to drug-free controls, is a time-consuming and difficult operation.…”

Long live the worms: methods for maintaining and assessing the viability of intestinal stages of Parascaris spp. in vitro

“…The ability to maintain gastro-intestinal helminths in vitro would enhance the experimental tractability of nematode parasites by facilitating the application of a range of molecular and biochemical tools and analyses in clinically relevant species. Such an advance would prompt a paradigm shift in parasitology research permitting progress in key areas including evaluation of anthelmintics and natural products with anthelmintic properties (Rapson et al ., 1985; Brownlee et al ., 1997; O'Grady and Kotze, 2004; Jansen et al ., 2013), application of transcriptomics to investigate the genetic mechanisms driving anthelmintic resistance (Jansen et al ., 2013), induction of RNAi interference for the identification of novel drug targets (McCoy et al ., 2015), analysis of excretory and secretory products (Young et al ., 1995; Geldhof et al ., 2000; Islam et al ., 2004; Cribb et al ., 2006; Burk et al ., 2014; Thomas et al ., 2016) and interrogation of host–parasite interactions (Kotze and McClure, 2001).…”