Specificity and affinity of neuraminic acid exhibited by canine rotavirus strain K9 carbohydrate-binding domain (VP8*)

The role and implication of rotavirus VP8∗ in viral infection and vaccine development

Rotaviruses (RVs) are major causative agents of diarrhea in both humans and animals worldwide. Despite the successful development of live attenuated vaccines, the efficacy of these vaccines remains low in developing countries and RV infections still result in more than 200,000 deaths in children under 5 years old globally each year. These viruses are also an enteric pathogen for agricultural animals and have caused substantial economic losses annually to the animal livestock industry. Frequent reassortment and the emergence of new RV strains continue to pose a significant challenge to human and agricultural animal health. Attachment to susceptible cells by recognizing cell surface glycans is the first step of the RV lifecycle, which is directed by the RV spike protein VP8∗. VP8∗-host glycan receptor interactions are thought to be strain-specific and play an important role in RV replication fitness, tropism, and cross-species transmission. This review will summarize the current understanding of the roles of VP8∗ in engagement of glycan receptors and its functional consequences in impacting RV replication fitness and host ranges. The current progress towards developing a VP8∗-based RV vaccine is also discussed in the review.

Structural and functional characterization of bovine G1P[5] rotavirus VP8* protein

The widely used rotavirus (RV) vaccine, Rotateq, contained reassortment strains of human and bovine G1/2/3/4P[5] RVs. The functional and structural features of bovine G1P[5] VP8* were investigated. Bovine G1P[5] VP8* was identified to interact with sialic acids and sialic acid-containing glycans. In addition, P[5] VP8* recognized α-Gal histo-blood group antigens (HBGAs). Bovine G1P[5] VP8* did not hemagglutinate the tested red blood cells. The crystal structure of P[5] VP8* was determined at 1.7 Å. Structural superimposition revealed that P[5] VP8* was most close to human P[8] VP8*, while much further to VP8*s of porcine P[7] and rhesus P[3]. Sequence alignment showed that amino acids of the putative glycan binding site in P[5] VP8* were different to those in P[3]/P[7] VP8*s, indicating that P[5] VP8* may interact with glycans using different mechanism. This study provided more understanding of P[5] RV infection and the interactions of RV VP8* and glycans.

Structural Basis of Glycan Recognition of Rotavirus

Rotavirus (RV) is an important pathogen causing acute gastroenteritis in young humans and animals. Attachment to the host receptor is a crucial step for the virus infection. The recent advances in illustrating the interactions between RV and glycans promoted our understanding of the host range and epidemiology of RVs. VP8*, the distal region of the RV outer capsid spike protein VP4, played a critical role in the glycan recognition. Group A RVs were classified into different P genotypes based on the VP4 sequences and recognized glycans in a P genotype-dependent manner. Glycans including sialic acid, gangliosides, histo-blood group antigens (HBGAs), and mucin cores have been reported to interact with RV VP8*s. The glycan binding specificities of VP8*s of different RV genotypes have been studied. Here, we mainly discussed the structural basis for the interactions between RV VP8*s and glycans, which provided molecular insights into the receptor recognition and host tropism, offering new clues to the design of RV vaccine and anti-viral agents.