Intrauterine infection of the rhesus monkey with mumps virus: abbreviated viral replication in the immature fetus as an explanation for split immunologic recognition after birth

Molecular biology, pathogenesis and pathology of mumps virus

Mumps is caused by the mumps virus (MuV), a member of the Paramyxoviridae family of enveloped, non-segmented, negative-sense RNA viruses. Mumps is characterized by painful inflammatory symptoms, such as parotitis and orchitis. The virus is highly neurotropic, with laboratory evidence of central nervous system (CNS) infection in approximately half of cases. Symptomatic CNS infection occurs less frequently; nonetheless, prior to the introduction of routine vaccination, MuV was a leading cause of aseptic meningitis and viral encephalitis in many developed countries. Despite being one of the oldest recognized diseases, with a worldwide distribution, surprisingly little attention has been given to its study. Cases of aseptic meningitis associated with some vaccine strains and a global resurgence of cases, including in highly vaccinated populations, has renewed interest in the virus, particularly in its pathogenesis and the need for development of clinically relevant models of disease. In this review we summarize the current state of knowledge on the virus, its pathogenesis and its clinical and pathological outcomes.

Infection of mice, ferrets, and rhesus macaques with a clinical mumps virus isolate

In recent years, many mumps outbreaks have occurred in vaccinated populations worldwide. The reasons for these outbreaks are not clear. Animal models are needed to investigate the causes of outbreaks and to understand the pathogenesis of mumps virus (MuV). In this study, we have examined the infection of three animal models with an isolate of mumps virus from a recent outbreak (MuV-IA). We have found that while both ferrets and mice generated humoral and cellular immune responses to MuV-IA infection, no obvious signs of illness were observed in these animals; rhesus macaques were the most susceptible to MuV-IA infection. Infection of rhesus macaques via both intranasal and intratracheal routes with MuV-IA led to the typical clinical signs of mumps 2 weeks to 4 weeks postinfection. However, none of the infected macaques showed any fever or neurologic signs during the experimental period. Mumps viral antigen was detected in parotid glands by immunohistochemistry (IHC). Rhesus macaques represent the best animal model for the study of mumps virus pathogenesis.

New syndrome of hydrocephalus, endocardial fibroelastosis, and cataracts (HEC syndrome)

We report on two unrelated male infants with similar findings of communicating hydrocephalus, endocardial fibroelastosis (EFE) and congenital cataracts, who died at 4 months of age. Both mothers reported an upper respiratory infection during the first trimester of pregnancy which was further complicated by polyhydramnios in the third trimester. The infants were diagnosed with bilateral congenital nuclear cataracts at birth. Serologic tests for toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus, syphilis, and galactosemia screens were negative. Chromosome analyses were normal. Both children developed communicating hydrocephalus between one and three months after birth. Patient 1 died suddenly at 4 months following an upper respiratory infection. Patient 2 developed congestive heart failure and also died at 4 months. At autopsy, both infants had enlarged hearts with endocardial fibroelastosis. No identifiable organism could be isolated. We discuss the association of birth defects in widely separated organ systems in these patients and suggest that this may represent a genetic syndrome; however, a viral etiology cannot entirely be excluded. We believe this is a distinct disorder and propose the acronym HEC for hydrocephalus, EFE and cataracts.

Maternal infections influence infection susceptibility in childhood

The proposed hypothesis suggests that the types of infections commonly experienced in pregnancy and in childhood are linked. The suggestion is made that maternal infections leave an impression on the developing fetal immune system and modulate future responsiveness to infection and/or vaccination challenge. A number of factors are explored which may influence this process, namely immunoregulation in pregnancy and infection type, gestation, maturity of the fetal immune system, and parity.

Unilateral hydrocephalus due to obstruction of the foramen of Monro: another complication of intrauterine mumps infection?

Unilateral hydrocephalus due to foramen of Monro-obstruction was diagnosed in a newborn who presented with macrocephaly at birth. The mother had mumps in the second trimester of pregnancy and immunological studies indicated possible intrauterine infection of the baby with mumps virus. His condition deteriorated rapidly, and he developed myoclonic seizures. The possible relationship of intrauterine mumps infection to neonatal neurological complications is discussed.

Intrauterine infection of mice with St. Louis encephalitis virus: immunological, physiological, neurological, and behavioral effects on progeny

Intravenous injection of pregnant mice with St. Louis encephalitis (SLE) virus at 8 days of gestation resulted in infection of the fetus. Progeny developed no antibody or tolerance to SLE virus since the viral antigen was cleared by maternal antibody before antibody-forming competence developed in the young. Temporary growth retardation was observed in a number of young at 3 weeks of age. After the initial setback the growth rate increased, indicating that early runting was due to an inability to adjust adequately to extrauterine life, which was subsequently overcome. In most other young there were no significant effects on growth, reproduction, or life expectancy. A few young died at or shortly after birth; in these, neurological changes ranging from gross defects such as encephaloceles and hydrocephalus to histological evidence of necrosis and congestion were observed. Neurologically related behavioral changes were detected by using the open field test and the rotating-rod test, which indicated neurological damage and memory impairment in the surviving intrauterinely infected animals.