Genome of the Giant Panda Roundworm Illuminates Its Host Shift and Parasitic Adaptation

Baylisascaris schroederi, a roundworm (ascaridoid) parasite specific to the bamboofeeding giant panda (Ailuropoda melanoleuca), represents a leading cause of mortality in wild giant panda populations. Here, we present a 293-megabase chromosome-level genome assembly of B. schroederi to infer its biology, including host adaptations. Comparative genomics revealed an evolutionary trajectory accompanied by host-shift events in ascaridoid parasite lineages after host separations, suggesting their potential for transmission and rapid adaptation to new hosts. Genomic and anatomical lines of evidence, including expansion and positive selection of genes related to the cuticle and basal metabolisms, indicate that B. schroederi undergoes specific adaptations to survive in the sharp-edged bamboo-enriched gut of giant pandas by structurally increasing its cuticle thickness and efficiently utilizing host nutrients through gut parasitism. Additionally, we characterized the secretome of B. schroederi and predicted potential drug and vaccine targets for new control strategies. Overall, this genome resource provides new insights into the host adaptation of B. schroederi to the giant panda as well as the host-shift events in ascaridoid parasite lineages. Our findings on the unique biology of B. schroederi will also aid in the development of prevention and treatment measures to protect giant panda populations from roundworm parasitism.

Automated summary

This study reveals the host adaptation of Baylisascaris schroederi to the giant panda and provides insights into the evolutionary trajectory of host-shift events in ascaridoid parasite lineages. The specific adaptations of B. schroederi to survive in the gut of giant pandas, such as increasing cuticle thickness and efficient utilization of host nutrients, are characterized. The findings of this study will aid in the development of prevention and treatment measures to protect giant panda populations from roundworm parasitism.