Amino acid change 335 E to K affects the sialic-acid-binding and neuraminidase activities of Urabe AM9 mumps virus hemagglutinin–neuraminidase glycoprotein

• DOI: 10.1016/j.micinf.2006.11.011
• Publication Date: 2006-12-19T14:32:17Z
• Authors: Julio Reyes-Leyva; Rocío Baños; María Borraz-Argü...; Gerardo Santos-López; Nora Rosas; Gabriela Alvarado; Irma Herrera; Verónica Vallejo; José Tapia-Ramírez
• Keywords: 0301 basic medicine; HN Protein; Mutation, Missense; Virus Attachment; N-Acetylneuraminic Acid; Cell Line; 3. Good health; 03 medical and health sciences; Amino Acid Substitution; Mumps virus; Chlorocebus aethiops; Animals; Humans; Receptors, Virus

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.