Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-26T03:00:24.987Z Has data issue: false hasContentIssue false

Onchocerca lienalis: comparison of techniques for the cryopreservation of microfilariae within skin-snips or free of host tissues

Published online by Cambridge University Press:  05 June 2009

S. K. Tagboto
Affiliation:
Tropical Parasitic Diseases Unit, International Institute of Parasitology, 395a Hatfield Road, St. Albans AL4 OXU, UK
S. Townson
Affiliation:
Tropical Parasitic Diseases Unit, International Institute of Parasitology, 395a Hatfield Road, St. Albans AL4 OXU, UK

Abstract

Onchocerca lienalis microfilariae (mf) were cryopreserved in liquid nitrogen within skin-snips using methanol as a cryoprotectant and their viability evaluated and compared to mf cryopreserved free of host tissues using ethanediol as a cryoprotectant. Despite an initial delay in emergence, the methanol technique did not significantly affect the total numbers of mf emerging from skin-snips of various sizes (3·3–59·81 mg) compared to untreated controls over a 6 h period. Following thawing, the initial motility index (MI) scores of mf cryopreserved by either method were not significantly different from untreated controls; however, over a period of 15 days in culture the MI scores of both cryopreserved groups showed a small but significant overall decline, with the methanol technique producing the lowest scores. These changes in motility levels correlated with the numbers of mf which developed to the infective stage following intrathoracic injection into Simulium ornatum, although this ability to develop was a much more sensitive measure of parasite viability; compared to untreated control recoveries of 3rd-stage larvae, 63·9–71·7% (ethanediol technique) and 34·2–36·9% (methanol technique) of this number were recovered from cyropreserved groups. There were no significant differences in the lengths of infective larvae recovered from the insect heads from each treatment group, nevertheless there were higher numbers of 2nd-stage larvae recovered from the cryopreserved groups compared to the untreated controls. The methanol technique has the advantage of being easier to carry Out under field conditions, while parasite viability is significantly better using the ethanediol technique.

Type
Research Papers
Copyright
Copyright © Cambridge University Press 1991

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Bianco, A. E., Ham, P. J., El-Sinnary, K. & Nelson, G. S. (1980) Large scale recovery of Onchocerca microfilariae from naturally infected cattle and horses. Transactions of the Royal Society for Tropical Medicine and Hygiene, 74, 109110.Google Scholar
Bianco, A. E., Ham, P. J., Townson, S., Mustafa, M. B. & Nelson, G. S. (1989) A semi-automated system of intrathoracic injection for the large-scale production of Onchocerca lienalis infective larvae. Tropical Medicine and Parasitology, 40, 5764.Google ScholarPubMed
El sheikh, H. & Ham, P. J. (1982) Human onchocerciasis: Cryopreservation of isolated microfilariae. The Lancer, 1, 50.Google ScholarPubMed
Ham, P. J., James, E. R. & Bianco, A. E. (1979) Onchocerca sp.: Cryopreservation of microfilariae and subsequent development in the insect host. Experimental Parasitology, 47, 384391.CrossRefGoogle Scholar
Ham, P. J. & Bianco, A. E. (1981) Quantification of a cryopreservation technique for Onchocerca microfilariae in skin snips. Journal of Helminthology, 55, 5961.CrossRefGoogle ScholarPubMed
Ham, P. J., Townson, S., James, E. R. & Bianco, A. E. (1981) An improved technique for the cryopreservation of Onchocerca microfilariae. Parasitology, 83, 139146.CrossRefGoogle ScholarPubMed
Ham, P. J. & Bianco, A. E. (1983) Development of Onchocerca volvulus from cryopreserved microfilariae in three temperate species of laboratory-reared blackflies. Tropenmedizin und Parasitologie, 34, 137139.Google ScholarPubMed
Schiller, E. L., Turner, V. M., Marroquín, H. F. & D'Antonio, R. (1979) The cryopreservation and in vitro cultivation of larval Onchocerca volvulus. American Journal of Tropical Medicine and Hygiene, 28, 9971009.Google ScholarPubMed
Townson, S.Connelly, C. & Muller, R. (1986) Optimization of culture conditions for the maintenance of Onchocerca gutturosa adult worms in vitro. Journal of Helminthology, 60, 323330.CrossRefGoogle ScholarPubMed
Townson, S., Shay, K. E., Dobinson, A. R., Comley, J. W. C. & Zea-flores, G. (1989) Onchocerca gutturosa and O. volvulus: Studies on the viability and drug responses of cryopreserved adult worms in vitro. Transactions of the Royal Society for Tropical Medicine and Hygiene, 83, 664669.CrossRefGoogle Scholar
Townson, S. & Tagboto, S. (1991) The effects of ivermectin on the viability of Onchocerca lienalis microfilariae in vitro and on their subsequent development in the blackfly vector, Simulium ornatum. Tropical Medicine and Parasitology, 42, 3137.Google ScholarPubMed