ABSTRACT
Infection in pregnant women is relatively common. For instance, 11 % of pregnant women are positive during the second and third trimesters for influenza.1 In fact, pregnancy is known to alter the immune system's response to infection.2,3 Although the mother may recover relatively quickly from an infection, the consequences for the fetus can be severe. Depending on the type and timing of infection, and the genotype of the mother and fetus, acute maternal infections can increase the incidence of miscarriage and stillbirth, as well as disorders in the offspring such as cerebral palsy4-7 and mental illness8-13 in the offspring. For instance, 'German measles' (rubella virus) or cytomegalovirus infection during the first trimester strongly increases the risk for autism in the offspring, leading one study to conclude that 'the principal nongenetic cause of autism is prenatal viral infection.'14 In addition, respiratory infection during the second trimester can increase the risk for schizophrenia in the offspring. ll ,12,15-20 Moreover, the presence of antiinfluenza antibodies or increased levels of interleukin (IL)-8 during the second trimester increases the risk for schizophrenia in the offspring.21 ,22
Given this morbidity and mortality, it is important to investigate the pathophysiology of maternal infection, as well as potential avenues of prevention and therapy. Moreover, because of this connection, studies in animal models could shed light on mental retardation, autism, and schizophrenia. These models have the advantage of being based on a known risk factor for the disorders. The present article briefly reviews the effects of maternal infection on the behavior of offspring. The offspring of infected rodents can be characterized in a number of ways, including via molecular and neuropathological studies of their brains. Behavioral assays can also be useful in charac-
terizing the mental status of these offspring. A number of relevant behavioral tests are being used in various rodent models of mental illness.23-27 These assays include motor activity, stereotypies, and the acoustic startle response, as well as tests of latent inhibition, social interaction, learning and memory, and responses to stressful environments. Of these assays, only a few have been used thus far in testing the offspring of infected or immune-activated mothers.
