New CCHFVACIM-supported study sheds light on CCHFV infection dynamics in sheep
A new study supported by the CCHFVACIM project provides detailed insights into how Crimean-Congo haemorrhagic fever virus (CCHFV) disseminates in sheep and how the animals’ immune response develops over time.
Published in npj Viruses, the study was led by researchers from the Friedrich-Loeffler-Institut, with contributions from Karolinska Institutet and international partners.
Sheep and other ruminants generally develop no obvious disease following CCHFV infection. However, they may carry the virus in their blood and transmit it to ticks or expose people who come into contact with infected blood and tissues. Understanding infection in these animals is therefore important for CCHFV surveillance, prevention and vaccine development.
The researchers experimentally infected six sheep with the CCHFV Kosovo Hoti strain and monitored them for 21 days. All animals developed a brief fever and transient viraemia, peaking three to four days after infection. Infectious virus was recovered from serum samples collected during the first days of infection.
At early time points, the highest viral RNA loads were found in the liver, spleen, testicles and lymphoid tissues. By days 20–21, viral RNA had been largely cleared from the organs, supporting a transient and self-limiting course of infection in this experimental model.
The study also characterised the animals’ immune response. Seroconversion began around seven days after infection, while virus-neutralising antibodies were detectable from day eight. The comparison of several serological assays revealed differences in the timing and type of antibodies detected, an observation that may help improve the interpretation of CCHFV serosurveillance studies in sheep.
These findings provide a more detailed picture of CCHFV infection in an important animal host. They also establish valuable data for the future development and evaluation of countermeasures, including vaccines designed to reduce viraemia and potentially limit transmission.
The study involved a small number of animals and used an experimental inoculation route rather than infection through tick bites. Further studies will therefore be needed to determine how closely these findings reflect natural infection in the field.
The research was supported by the European Commission through the CCHFVaccine and CCHFVACIM projects, as well as by USDA-ARS.
Read the article:
Gutjahr B. et al. Viral dissemination and diagnostic insights from experimental infection of sheep with Crimean-Congo hemorrhagic fever virus. npj Viruses 4, 39 (2026).
