“Tick by tick” refers to a study on Crimean-Congo hemorrhagic fever virus done at the University of Texas Medical Branch at Galveston (UTMB). This is a deadly virus carried by ticks and requires biosafety level 4 contamination protocols and maximum containment “spacesuit labs” to prevent transmission.
According to professor Dennis Bente at UTMB, senior author of a paper describing the BSL4 tick work in Frontiers in cellular and Infection Microbiology, “It was completely new territory for us. Ticks are very small, and in the BSL4 you have two pairs of gloves on, you have this bulky suit, you have the plastic visor—all these things are a huge handicap. So how do you make sure you contain them?”
Bente and colleagues answer by saying: step by painstaking step. What they did was to attach small feeding capsules onto mice, and then place ticks into the capsules. Once the ticks became attached to the mice, they were moved into a room in the Galveston National Laboratory BSL4 and set aside for tick research.
Once the ticks had attached to the mice, the mice were inoculated with Crimean-Congo hemorrhagic fever virus. The encapsulated ticks began feeding on the blood of the mice and acquired the deadly virus. Each tick that was encapsulated was observed and accounted for through every stage of the experiment.
Bente notes that, “We did hours upon hours of testing to get this system working. We tested different types of sticky tape to determine the one that best inhibited the ticks’ mobility, we tried different gloves, we tested the work flow, we checked to see how long a tick could last if you submerge it in disinfectant.” (The answer: more than 24 hours)
Bente reports that the outcome of this was a tool that will provide scientists with a virtually unknown side of one of the world’s most vastly distributed hemorrhagic fever viruses. This virus is a pathogen known for its outbreaks from Greece to India to South Africa.
Bente points out that, “Ticks play such a vital role in the epidemiology of the disease — they’re not only the vector but they are also the reservoir for the virus, yet nobody really knows what’s happening to the virus in the ticks, because there’s been no way to study it in the laboratory. Now we can look at the complete transmission cycle in a controlled setting, examining how the virus is passed from infected animal to the uninfected tick, and from the infected tick to the uninfected animal. That’s something that people studying this in the field haven’t been able to do before now.”
The new protocol will allow researchers to study this particular virus’ transmission with other species of ticks. For example, North American ticks which carry West Nile virus but could potentially carry Crimean-Congo hemorrhagic fever virus into the United States.
Photo from http://www.cbwinfo.com