T Vermeire1, C Barbezange2, A Francart2, A Hamouda2, A Litzroth3, V Hutse2, L Martens4, E Vandermarliere4, S Van Gucht5. 1. Department of Viral Diseases, Sciensano, Brussels, Belgium; Department of Biomolecular Medicine, Ghent University, Ghent, Belgium; Center for Medical Biotechnology, VIB, Ghent, Belgium. 2. Department of Viral Diseases, Sciensano, Brussels, Belgium. 3. Service of Epidemiology Infectious Diseases, Sciensano, Brussels, Belgium. 4. Department of Biomolecular Medicine, Ghent University, Ghent, Belgium; Center for Medical Biotechnology, VIB, Ghent, Belgium. 5. Department of Viral Diseases, Sciensano, Brussels, Belgium. Electronic address: steven.vangucht@sciensano.be.
Abstract
OBJECTIVES: Mumps used to affect children between 2 and 15 years old. The mumps-measles-rubella (MMR) vaccine is available, with vaccine coverage rate of about 85% after two vaccine doses. Recently new mumps outbreaks have emerged in highly vaccinated populations; the causes for these new outbreaks are yet unknown. We tested if a difference in seroneutralizing capacity against the vaccine and wild-type viruses existed and if waning immunity could be detected. METHODS: In this study, 570 serum samples (age group 2-3 years (n = 96), 8-9 years (n = 95), 13-14 years (n = 94), 18-20 years (n = 96), 24-26 years (n = 92) and 50 + years (n = 97)) in Belgium were tested in the rapid fluorescent foci inhibition test for their neutralizing capacity against the vaccine and wild-type viruses. RESULTS: Neutralizing antibodies against the vaccine strain were present in 84% (81/97) of the 2-3-year, 74% (70/95) of the 8-9-year, 81% (76/94) of the 13-14-year, 76% (73/96) of the 18-20-year, 67% (62/92) of the 24-26-year and 77% (75/97) of the 50+-year age group serum samples. For all age groups, only about half of these serum samples were also positive for the wild-type virus. The geometric mean titres for the vaccine and wild-type virus for all younger age groups, except for 24-26 years, were significantly different, demonstrating poor in vitro cross-neutralization. CONCLUSIONS: A possible contribution of antigenic differences between the genotype A and G mumps virus as well as other immune factors, in addition to lower-than-optimal vaccination coverage and waning immunity, could explain the poor in vitro cross-neutralization and should be further studied.
OBJECTIVES: Mumps used to affect children between 2 and 15 years old. The mumps-measles-rubella (MMR) vaccine is available, with vaccine coverage rate of about 85% after two vaccine doses. Recently new mumps outbreaks have emerged in highly vaccinated populations; the causes for these new outbreaks are yet unknown. We tested if a difference in seroneutralizing capacity against the vaccine and wild-type viruses existed and if waning immunity could be detected. METHODS: In this study, 570 serum samples (age group 2-3 years (n = 96), 8-9 years (n = 95), 13-14 years (n = 94), 18-20 years (n = 96), 24-26 years (n = 92) and 50 + years (n = 97)) in Belgium were tested in the rapid fluorescent foci inhibition test for their neutralizing capacity against the vaccine and wild-type viruses. RESULTS: Neutralizing antibodies against the vaccine strain were present in 84% (81/97) of the 2-3-year, 74% (70/95) of the 8-9-year, 81% (76/94) of the 13-14-year, 76% (73/96) of the 18-20-year, 67% (62/92) of the 24-26-year and 77% (75/97) of the 50+-year age group serum samples. For all age groups, only about half of these serum samples were also positive for the wild-type virus. The geometric mean titres for the vaccine and wild-type virus for all younger age groups, except for 24-26 years, were significantly different, demonstrating poor in vitro cross-neutralization. CONCLUSIONS: A possible contribution of antigenic differences between the genotype A and G mumps virus as well as other immune factors, in addition to lower-than-optimal vaccination coverage and waning immunity, could explain the poor in vitro cross-neutralization and should be further studied.