Vaccination of all giant pandas in captivity against canine distemper virus (CDV) may be warranted to support conservation efforts for this endangered species, suggests a study in Scientific Reports.
An eight-year-old giant panda named Chengcheng presented with jaw trembling and convulsions of the limbs, symptoms of CDV, at the Shanxi Rare Wild Animal Rescue and Research Centre in China in December 2014. Over the ensuing fourteen weeks four additional pandas housed in the same or adjacent rooms began to display clinical signs of CDV. Each of the five pandas displaying symptoms of infection died 7-34 days following the onset of the disease. CDV was also detected in an asymptomatic giant panda named Zhuzhu, who was previously vaccinated against CDV in 2012.
After isolating CDV from lung and spleen tissue from one of the infected pandas, Yuwei Gao and colleagues sequenced the genome of the virus responsible for this outbreak. They identified five mutations encoded in the H gene of CDV, which have not been previously observed in Asia-1 strains. The authors suggest that one of the mutations - a substitution of an amino acid at position 549 of the H protein - may have been responsible for the high-level of virulence associated with this outbreak.
The authors argue that the recovery of CDV genomic material from Zhuzhu suggests that the immune responses elicited by CDV vaccination were not sufficient to prevent infection, but may have reduced the virulence of the disease. They suggest that heightened surveillance and CDV vaccination should be considered in all facilities housing captive giant pandas.