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Crimean-Congo Hemorrhagic Fever: New NHP Model Developed

Crimean Congo Hemorrhagic Fever (CCHF)
Scanning electron micrograph of CCHF viral particles (yellow) budding from the surface of cultured epithelial cells from a patient. Credit: NIAID

Researchers have developed a new non-human primate (NHP) animal model to study Crimean-Congo hemorrhagic fever (CCHF), a viral disease spread by ticks in the Middle East, Asia, Africa and parts of Europe.

No specific treatments or vaccines for exist, primarily because a suitable animal model for studying the disease has not been available.

Scientists at the National Institute of Allergy and Infectious Diseases (NIAID) conducted a pilot study using CCHF virus to infect African green monkeys, rhesus macaques, and cynomolgus macaques. The strain of the virus they used, known as Kosova Hoti, was isolated from the blood of a person who died of CCHF.

The first two monkey species showed no signs of disease using various inoculation methods. Two of three cynomolgus macaques, however, developed disease. That led to a larger study of 12 cynomolgus macaques, four each inoculated under the skin, intravenously, or a combination of both. Within three days, all eight animals in the combination and intravenous groups showed signs of infection that led to severe disease. Two of the four animals inoculated under the skin developed mild signs of disease while the other two remained symptom-free.

Crimean Congo Hemorrhagic Fever Distribution Map
Crimean-Congo Hemorrhagic Fever (CCHF) Distribution Map. Credit: CDC

Disease progression in the cynomolgus macaques followed the four phases that most infected people experience: 1) A 3- to 4-day incubation period; 2) a 3- to 5-day pre-hemorrhagic period; 3) a 2-to 3-day hemorrhagic period; and 4) recovery or death.

Because their study included cynomolgus macaques that experienced a range of conditions, from no CCHF symptoms to severe disease, the scientists believe this animal model will be useful for examining how the infection progresses and interacts with the immune system. Ultimately, they plan to use the model to develop treatments and vaccines for CCHF.

Read more: E Haddock, et al. A cynomolgus macaque model for Crimean–Congo haemorrhagic feverNature Microbiology DOI: 10.1038/s41564-018-0141-7 (2018).

Sources: Adapted from the U.S. Centers for Disease Control and Prevention and National Institutes of Health

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