Treatment for MERS May Be Discovered Through Alpacas

An international team of researchers may have identified a potential animal model for use in the laboratory as part of efforts to better understand the pathogenesis of Middle East respiratory syndrome (MERS) coronavirus and, hopefully, find an effective treatment for it: alpacas.

Their findings were published online on June 1 in the journal Emerging Infectious Diseases (EID).

To date, MERS coronavirus has largely confounded researchers and clinicians alike, with devastating results. More than 1,600 cases have been confirmed since the virus was first identified in 2012, and nearly 40% of them have resulted in fatalities.

Earlier studies published by this same group, made up of scientists from Colorado State University and the University of Queensland in Australia, had proposed using dromedary camels as animal models in MERS research. However, although their work found that these camels were suitable models, their size, cost, and the need for specialized facilities in which to conduct research using them limited their utility.

Conversely, alpacas, which typically measure three feet in height and weigh less than 200 pounds, would appear to be easier to manage in the laboratory setting. The authors experimented with 9 adult alpacas, initially infecting 3 of them with MERS coronavirus as part of the study. All 3 had detectable virus within 5 days postinfection, but stopped shedding virus by day 10. The researchers housed 3 more alpacas with the infected group 2 days following initial virus infection, and detected MERS coronavirus in 2 of the 3 by day 14. They detected neutralizing antibodies in all 3 within 14 days, suggesting viral transmission.

Overall, the researchers reported that MERS-infected alpacas “shed considerable quantities of infectious virus nasally, although at lower concentrations than those reported for dromedary camels, [although] none of the infected alpacas had a noticeable nasal discharge, which… might explain the relatively low efficiency of contact transmission...” In addition, they found that “experimentally infected alpacas were completely protected against subsequent virus rechallenge, and contact-infected alpacas were only partially protected.”

Although the researchers did not respond to requests for comment at press time, they wrote in their concluding remarks that “a major question related to the pathogenesis of MERS-coronavirus infection in camels, and of great relevance to vaccination strategies, is whether animals that have been infected are resistant to reinfection and virus shedding and, if so, for how long?”

They continue, “Our experimentally infected animals were completely protected against rechallenge 70 days later, which suggests that sterilizing immunity can be achieved. However, the animals that were infected through contact shed infectious virus after reinfection, albeit at much lower levels than infected control animals.”

According to the authors, “these results support field data that suggest that young animals become infected and probably receive booster infections; most older animals have acquired immunity and are not susceptible to infection and virus shedding. This finding also highlights the possibility that widespread vaccination of dromedary camels could result in a major decrease in virus transmission to humans.”

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.