a1 Institute of Immunology, Department for Research and Development, Zagreb, Croatia
a2 Institute of Immunology, Unit for Experimental Animals, Sveta Nedelja, Croatia
a3 Croatian National Institute of Public Health, Department of Virology, Zagreb, and School of Medicine, University of Zagreb, Zagreb, Croatia.
A recent resurgence of mumps in doubly vaccinated cohorts has been observed, identifying genotype G as the current predominant genotype. In this study, the neutralization efficacy of guinea pig sera immunized with three vaccine viruses: L-Zagreb, Urabe AM9 and JL5, was tested against seven mumps viruses: three vaccine strains and four wild-type strains (two of genotype G, one of genotype C, one of genotype D) isolated during 1998–2011. All sera neutralized all viruses although at different levels. The neutralization efficiency of sera decreases several fold by temporal order of virus isolation. Therefore, we concluded that gradual evolution of mumps viruses, rather than belonging to a certain genotype, results in an antigenic divergence from the vaccine strains that decrease the neutralization capacity of vaccine-induced antibodies. Moreover, the amino-acid sequence alignment revealed three new potentially relevant regions for escape from neutralization, i.e. 113–130, 375–403 and 440–443.
(Received April 24 2012)
(Revised July 10 2012)
(Accepted August 03 2012)
(Online publication September 07 2012)
c1 Author for correspondence: M. Šantak, Ph.D., Institute of Immunology, Molecular Biomedicine Unit, Department for Research and Development, Rockefellerova 10, CRO-10000 Zagreb, Croatia. (Email: firstname.lastname@example.org)