Effects of influenza, mumps, and western equine encephalitis viruses on fetal rhesus monkeys (Macaca mulatta).

The research study explored the impact of influenza, mumps, and western equine encephalitis viruses on the fetuses of Rhesus monkeys. It found that all these viruses could infect fetal tissue with mumps and western equine encephalitis causing significant fetal death and deformities respectively.

Study Design and Methodology

• The research involved infecting pregnant Rhesus monkeys with influenza, mumps, and western equine encephalitis viruses. The infection was introduced into the amniotic sacs of the monkeys around 90 days into their gestation period.
• The main aim of the study was to determine whether these viruses would cause infection in the fetuses. Seven days post-infection, fetal tissues were taken from the exposed animals for examination.
• In addition to this, the fetuses were also directly inoculated with the viruses through an intracerebral route to establish if they possessed any teratogenic properties, which refers to their potential to cause developmental malformations or defects.

Study Findings and Conclusions

• The study found that virus was recoverable from the fetal tissues in 100% of the animals, proving that all the three viruses are capable of causing fetal infections.
• In terms of teratogenic properties, the study found differentiated results based on the type of virus. It observed that the influenza virus did not cause any malformations or effects that could be measured.
• In contrast, the mumps virus resulted in significant fetal mortality, implying a major negative impact. The western equine encephalitis virus was found to cause encephalitis and hydrocephalus in all cases, linking it with developmental abnormalities.
• Based on these findings, the researchers concluded that while influenza might be safe in context to fetal development, both mumps and western equine encephalitis viruses pose significant teratogenic risks and could potentially be harmful for human fetuses as well.