Last August, in Study: Experimental Infection Of Goats, Sheep & Horses With MERS-CoV, we looked at a study that reassuringly found that:
Minimal or no virus shedding was detected in all of the animals. During the four weeks following inoculation, neutralizing antibodies were detected in the young goats, but not in sheep or horses.
Among common livestock tested, only camels and alpacas - a member of the same biological family (Camelidae) as dromedaries - have been found both susceptible to MERS infection and able to shed large quantities of the virus.
But today we've a new study that suggests that pigs (not initially tested because they are not commonly raised in the Middle East) may need to be added to the short list of livestock that can carry the MERS virus.The susceptibility of swine to MERS is perhaps not all that surprising, given that pigs are known to be infected by a variety of Coronaviruses, several of which we've looked at in the past few years;
- We took our first detailed look in October of 2013, in mBio: PEDV - Porcine Epidemic Diarrhea Virus - An Emerging Coronavirus. While distantly related to SARS and MERS (both are betacoronaviruses), PEDV is an alphacoronavirus.
- In early 2014, the Ohio Department of Agriculture officially announced that a never-before-seen porcine deltacoronavirus (PDCoV) had been identified in the United States (see New, non-PED Coronavirus detected in pigs with diarrhea).
- With a plethora of porcine pathogens to deal with , the USDA lumped them together in 2014 into the general category of SECD – or Swine Enteric Coronavirus Diseases.
I've only included some brief excerpts from a much longer report. Follow the link to read it in its entirety.
Volume 23, Number 2—February 2017
Livestock Susceptibility to Infection with Middle East Respiratory Syndrome Coronavirus
Middle East respiratory syndrome (MERS) cases continue to be reported, predominantly in Saudi Arabia and occasionally other countries. Although dromedaries are the main reservoir, other animal species might be susceptible to MERS coronavirus (MERS-CoV) infection and potentially serve as reservoirs.
To determine whether other animals are potential reservoirs, we inoculated MERS-CoV into llamas, pigs, sheep, and horses and collected nasal and rectal swab samples at various times.
The presence of MERS-CoV in the nose of pigs and llamas was confirmed by PCR, titration of infectious virus, immunohistochemistry, and in situ hybridization; seroconversion was detected in animals of both species.
Conversely, in sheep and horses, virus-specific antibodies did not develop and no evidence of viral replication in the upper respiratory tract was found. These results prove the susceptibility of llamas and pigs to MERS-CoV infection. Thus, the possibility of MERS-CoV circulation in animals other than dromedaries, such as llamas and pigs, is not negligible.
Epidemiologic studies have provided evidence of endemic MERS-CoV infection among dromedaries in the Greater Horn of Africa as far back as 1983 (23,24) and in Saudi Arabia as far back as 1992–1993 (25). To implement optimal serologic surveillance in countries where MERS is and is not endemic, identifying which animal species might be potential reservoirs for MERS-CoV, besides dromedaries, is crucial.
The finding that pigs can be infected with MERS-CoV suggests that other members of the family Suidae could be susceptible to the virus, such as common warthogs (Phacochoerus africanus), bushpigs (Potamochoerus larvatus), and wild boars (Sus scrofa scrofa). Indeed, these animals are commonly found in the Greater Horn of Africa or the Middle East, sharing territories and water sources with dromedaries.
Thus, members of the family Suidae might merit inclusion in MERS surveillance programs. Further studies need to be done to investigate MERS-CoV transmission within and among species to provide a better understanding of the role of potential reservoirs during an outbreak. Moreover, studies comparing the innate immunity of horses with susceptibility of other animal species (i.e., dromedary camels, alpacas, llamas, or pigs) are needed.
Dr. Vergara-Alert is a postdoctoral researcher at IRTA-CReSA (Barcelona). Her main research areas of interest are emerging and zoonotic diseases, animal models, vaccines, and treatments.