The EG95 antigen of Echinococcus spp. contains positively selected amino acids, which may influence host specificity and vaccine efficacy

Haag, K.L.; Gottstein, B.; Ayala, F.J. (2009). The EG95 antigen of Echinococcus spp. contains positively selected amino acids, which may influence host specificity and vaccine efficacy. PLoS ONE, 4(4), e5362. Lawrence, Kans.: Public Library of Science 10.1371/journal.pone.0005362

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Echinococcosis is a worldwide zoonotic parasitic disease of humans and various herbivorous domestic animals (intermediate hosts) transmitted by the contact with wild and domestic carnivores (definitive hosts), mainly foxes and dogs. Recently, a vaccine was developed showing high levels of protection against one parasite haplotype (G1) of Echinococcus granulosus, and its potential efficacy against distinct parasite variants or species is still unclear. Interestingly, the EG95 vaccine antigen is a secreted glycosylphosphatydilinositol (GPI)-anchored protein containing a fibronectin type III domain, which is ubiquitous in modular proteins involved in cell adhesion. EG95 is highly expressed in oncospheres, the parasite life cycle stage which actively invades the intermediate hosts. After amplifying and sequencing the complete CDS of 57 Echinococcus isolates belonging to 7 distinct species, we uncovered a large amount of genetic variability, which may influence protein folding. Two positively selected sites are outside the vaccine epitopes, but are predicted to alter protein conformation. Moreover, phylogenetic analyses indicate that EG95 isoform evolution is convergent with regard to the number of beta-sheets and alpha-helices. We conclude that having a variety of EG95 isoforms is adaptive for Echinococcus parasites, in terms of their ability to invade different hosts, and we propose that a mixture of isoforms could possibly maximize vaccine efficacy.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Institute of Parasitology

UniBE Contributor:

Gottstein, Bruno

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 15:25

Last Modified:

19 Jul 2018 16:06

Publisher DOI:

10.1371/journal.pone.0005362

PubMed ID:

19401778

Web of Science ID:

000265601100009

BORIS DOI:

10.7892/boris.38337

URI:

https://boris.unibe.ch/id/eprint/38337 (FactScience: 221172)

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