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Updated: Jun 29, 2026
Modeling Ascending Vaginal Infection, Preterm Birth, and Neonatal Morbidity in Mice
Published on: October 10, 2025
Fetal death persists through recurrent pregnancies in mice following Ljungan virus infection
Annika Samsioe1, Ake Sjöholm, Bo Niklasson
1Karolinska Institutet, Department of Clinical Science and Education, Södersjukhuset, Division of Internal Medicine. SE-118 83 Stockholm, Sweden. Annika.Samsioe@Sodersjukhuset.se
Objectives:
Laboratory mice infected with Ljungan virus (LV) early in pregnancy suffer from perinatal death. Here we investigate the persistence of that effect through the outcome of consecutive pregnancies in LV-infected mice.
Study Design:
CD-1 mice were infected while pregnant and their adult female offspring were followed in parallel with uninfected control mice during repeated pregnancies. Three mating attempts resulted in two or three pregnancies per dam. The outcome of the last pregnancy was carefully monitored.
Results:
Both the dams infected as adults and their adult female offspring suffered perinatal deaths during the last pregnancy which occurred approximately 6 months after the original LV exposure and acute infection. The non-infected control animals experienced no perinatal death.
Conclusions:
Perinatal death persists across recurrent pregnancies in this mouse model of LV infection, both in animals infected as adults and in females exposed to the virus in utero. This implies that LV persists in mice long after initial infection, and is maintained in a quiescent state but can remain pathogenic in later pregnancies.
