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Sialic Acid-Binding Activity of S-Protein Facilitates Infection by Porcine TGE Coronavirus

by 5m Editor
11 October 2011, at 12:00am

Sialic acid-binding activity facilitates the infection by transmissible gastroenteritis coronavirus (TGEV) under unfavourable environmental conditions, and this activity varies between vrus strains, according to researchers based in Hanover, Germany.

Transmissible gastroenteritis virus (TGEV) has a sialic acid-binding activity that is believed to be important for enteropathogenicity, but that has so far appeared to be dispensable for infection of cultured cells, according to Christel Schwegmann-Weßels of the University of Veterinary Medicine in Hanover, Germany and co-authors there and at Centro Nacional de Biotecnología in Madrid, Spain and Institut National de la Recherche Agronomique (INRA) in Jouy-en-Josas, France.

In their paper published recently in Virology Journal, they explain that the aims of their study were to determine the effect of sialic acid-binding for the infection of cultured cells under unfavourable conditions, and comparison of TGEV strains and mutants, as well as the avian coronavirus, IBV, concerning their dependence on the sialic acid-binding activity.

The infectivity of different viruses was analysed by a plaque assay after adsorption times of 5, 20 and 60 minutes. Prior to infection, cultured cells were either treated with neuraminidase to deplete sialic acids from the cell surface, or mock-treated. In a second approach, pre-treatment of the virus with porcine intestinal mucin was performed, followed by the plaque assay after a five-minute adsorption time. A student's t-test was used to verify the significance of the results.

The researchers found that desialylation of cells only had a minor effect on the infection by TGEV strain Purdue 46 when an adsorption period of 60 minutes was allowed for initiation of infection. However, when the adsorption time was reduced to five minutes the infectivity on desialylated cells decreased by more than 60 per cent. A TGEV PUR46 mutant (HAD3) deficient in sialic acid binding showed a 77 per cent lower titre than the parental virus after a five-minute adsorption time. After an adsorption time of 60 minutes, the titre of HAD3 was 58 per cent lower than that of TGEV PUR46. Another TGEV strain, TGEV Miller, and IBV Beaudette showed a reduction in infectivity after neuraminidase treatment of the cultured cells, irrespective of the virion adsorption time.

Schwegmann-Weßels and co-authors concluded their results suggest that the sialic acid-binding activity facilitates the infection by TGEV under unfavourable environmental conditions. The dependence on the sialic acid-binding activity for an efficient infection differs in the analysed TGEV strains.

Reference

Schwegmann-Weßels C., S. Bauer, C. Winter, L. Enjuanes, H. Laude and G. Herrler. 2011. The sialic acid binding activity of the S protein facilitates infection by porcine transmissible gastroenteritis coronavirus. Virology Journal, 8:435. doi:10.1186/1743-422X-8-435

Further Reading

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Further Reading

- Find out more information on TGE by clicking here.


October 2011