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Reyes-Leyva, J, Baños, R, Borraz-Argüello, M, Santos-López, G, Rosas, N, Alvarado, G, Herrera, I, Vallejo, V and Tapia-Ramírez, J (2007) Amino acid change 335 E to K affects the sialic-acid-binding and neuraminidase activities of Urabe AM9 mumps virus hemagglutinin-neuraminidase glycoprotein. Microbes Infect. 9:234-40
A mutation coding for the amino acid change E335 to K is frequently found in the hemagglutinin-neuraminidase (HN) gene of Urabe AM9 mumps viruses isolated during post-vaccination meningitis cases. To identify if this mutation modifies the biological activities of the HN glycoprotein, two variants of Urabe AM9 vaccine differing at amino acid 335 (HN-E335 and HN-K335) were isolated and their receptor-binding specificity was determined by means of competence assays. Pre-incubation of the viruses with sialic acids inhibited both syncytia formation in Vero cells and replication in SH-SY5Y cells. Thus, HN-K335 showed higher affinity towards sialylalpha2,6lactose, whereas HN-G335 preferred sialylalpha2,3lactose. These results are relevant because a high expression of sialylalpha2,6lactose in nerve cells was confirmed by means of Sambucus nigra lectin-cytochemistry. In addition, kinetics assays showed that HN-K335 and HN-E335 also differ in their hydrolysis rate (Vmax values of 37.5 vs. 3.5 nmol min-1mg-1, respectively). Therefore, HN-K335 variant presented a neuraminidase activity level 11-fold higher than that of HN-E335 variant. In conclusion, the mutation affects the receptor-binding and neuraminidase activities of Urabe AM9 mumps virus variants.
Amino Acid Substitution; Animals; Cell Line; Cercopithecus aethiops; HN Protein/chemistry; HN Protein/genetics; HN Protein/metabolism; Humans; Mumps virus/genetics; Mumps virus/physiology; Mutation, Missense; N-Acetylneuraminic Acid/metabolism; Receptors, Virus/metabolism; Virus Attachment
|Gene product||Qualifier||GO Term||Evidence Code||with/from||Aspect||Extension||Notes||Status|
|GO:0004308: exo-alpha-sialidase activity||
Fig. 3 shows the presence of sialic acid that was produced by using direct fluorescence.
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