Prenatal Diagnosis of Congenital Lymphocytic Choriomeningitis Virus Infection: A Case Report

Lymphocytic Choriomeningitis Virus Infections in Hungary between 2017-2023-Investigation of the First Congenital Infections

Lymphocytic choriomeningitis virus (LCMV) is a neglected rodent-borne arenavirus, primarily spread by common house mouse species. Acquired human infections range from asymptomatic to mild flu-like symptoms and self-resolving neurological diseases. In contrast, intrauterine LCMV infection is associated with high mortality and morbidity. Infection of the fetus often leads to fetal death, and surviving fetuses may develop vision impairment and central nervous system developmental disorders. LCMV is mainly diagnosed by serological methods using in-house indirect immunofluorescence assays. LCMV nucleic acid is detected by the nested RT-PCR method and confirmed by Sanger sequencing. In Hungary, 23 acquired lymphocytic choriomeningitis cases were diagnosed between 2017 and 2023. Ten out of 23 confirmed patients proved to be positive by the PCR method. Two cases of intrauterine LCMV infections were detected in 2019 and 2021, respectively. The IgG antibody titers measured in the infant's serum samples were much higher than the IgG titers of the maternal serum samples. Both IgM and IgA antibodies were detectable in the infants' sera. As the microbiological diagnosis of LCMV is rather challenging and the symptoms are very similar to the clinical picture of other common teratogenic pathogens such as cytomegalovirus or Toxoplasma gondii, intrauterine LCMV infections might still be underdiagnosed.

Transmission, seroprevalence, and maternal-fetal impact of lymphocytic choriomeningitis virus

Congenital infections can have devastating short- and long-term impacts on the developing fetus. Lymphocytic choriomeningitis virus (LCMV) is a zoonotic pathogen of concern that causes a severe congenital syndrome but is under-recognized and under-studied. Herein we review data on the natural animal reservoirs of LCMV, modes of transmission to humans, seroprevalence of LCMV worldwide in both pregnant and non-pregnant individuals, mechanisms of viral dissemination to placenta and fetus, and impact of climate change on viral transmission. We highlight opportunities to enhance awareness of congenital LCMV and provide recommendations for prevention and monitoring among at-risk pregnant people. IMPACT: Key message of the article: LCMV is a zoonotic virus that poses a major threat to maternal-fetal health. Adds to the existing literature: We comprehensively address transmission of LCMV from the natural reservoir to the pregnant individual, placenta, and fetus. Impact: Available data call for enhanced patient and provider awareness about congenital LCMV during pregnancy, as well as a need for efforts to better define the seroprevalence and impact of congenital LCMV worldwide.

Lymphocytic choriomeningitis virus injures the developing brain: effects and mechanisms

Lymphocytic choriomeningitis virus (LCMV) is a prevalent pathogen, whose natural host and reservoir is the wild mouse. Humans can be infected when they contact the secretions of mice. Most infections of postnatal humans result in mild illness. However, the consequences can be severe when the infection occurs during pregnancy, as the virus crosses the placenta to infect the fetus. LCMV infection of the human fetus can lead to severe neuropathologic effects, including microencephaly, hydrocephalus, focal destructive lesions, and cerebellar hypoplasia. Outcomes among children with congenital LCMV are variable, but most are permanently and severely disabled. The neonatal rat inoculated with LCMV models human prenatal infection. The rat model has demonstrated that effects of LCMV depend on host age at the time of infection. Some effects, including encephalomalacia and neuronal migration disturbances, are immune-mediated and depend on the actions of T-lymphocytes. Other effects, including cerebellar hypoplasia, are virus-mediated and do not depend on T-lymphocytes. Cerebellar neuronal migration disturbances are caused by immune-mediated corruption of Bergmann glia structure. The rat pup inoculated with LCMV is a superb animal model for human congenital infection. All neuropathologic effects observed in human congenital LCMV infection can be recapitulated in the rat model. IMPACT: Lymphocytic choriomeningitis virus (LCMV) is a prevalent human pathogen that can cause serious neurologic birth defects when the infection occurs during pregnancy. The effects of the virus on the developing brain depend strongly on the age of the host at the time of infection. Some of the pathologic effects of LCMV are immune-mediated and are driven by T-lymphocytes, while other pathologic effects are due to the virus itself.