The efficiency of rotavirus A spread to extraintestinal tissues is not determined by the levels of its replication in the gut

Rotavirus A (RVA) spreads to multiple extraintestinal organs; however, it is not well understood what viral or host characteristics regulate the efficiency of this spread. We conducted this study to determine whether more efficient intestinal RVA replication leads to a higher rate of its extraintestinal spread. We also examined the distribution of known RVA glycan receptors in different tissues to better understand their potential role in facilitating viral dissemination to extraintestinal sites. We inoculated germ-free pigs with porcine OSU G5P[7] characterized by remarkably robust in vitro/in vivo replication, and G9P[13] which replicates to low-to-moderate titers and several other strains. Significantly higher RVA titers were observed in intestinal tissue/contents/feces of pigs infected with G5P[7], whereas G9P[13] was associated with a relatively modest intestinal replication but the most efficient extraintestinal spread. As expected, and coinciding with the increased sialic acid/glycan abundance and diversity, all RVA strains replicated to highest titers in the gut. Further, among the examined extraintestinal tissues, the lungs: a) had the highest frequency of RVA RNA detection; b) exhibited the highest host glycan diversity/abundance; and c) represented the only extraintestinal tissue in which both gross and microscopic lesions were observed. This further underscores the association between the RVA receptor diversity and respiratory lesions. This is the first experimental evidence that RVA extraintestinal spread does not depend on its replication efficiency in the gut. Additionally, these findings may provide an explanation for the current global dominance of G9P[13] and related RVA strains, which could be capable of airborne spread.