Mumps virus neutralizing antibodies do not protect against reinfection with a heterologous mumps virus genotype

In April 1999, a previously healthy 22-year-old woman was taken ill with fe ver and bilateral swelling of the parotid glands. A chronic course of disea se extending from April to December was found with swelling of the parotid glands, fatigue, low grade fever, episodes of tachycardia and nightswetting . Mumps virus RNA of genotype A character based on the SH (small hydrophobi c) protein gene classification was demonstrated in three serum samples coll ected during the course of clinical disease. Different criteria for reinfec tion were fulfilled including demonstration of IgG antibodies by ELISA in a preinfection serum sample. The preinfection serum sample of the patient wa s able to efficiently neutralize the infectivity of a heterologous genotype D strain but was unable to neutralize the homologous genotype A virus. The findings in the present study may offer an explanation of a mechanism behi nd previously observed vaccine failures and the occurrence of reinfection w ith heterologous mumps virus strains. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.