Isolation and passaging of reptarenaviruses utilizing cultured snake cells suggest tissue tropism and restrictions in segment reassortment

Reptarenaviruses cause boid inclusion body disease that can affect the fitness of the infected animals through a variety of clinical signs. Reptarenaviruses infect most tissue types in the affected individuals and spread efficiently in captive snake collections. Their genome consists of a small (S) and a large (L) segment, and the reptarenavirus-infected snakes often carry multiple genetically divergent reptarenavirus S and L segments, suggesting reptarenavirus coinfections occur frequently. We previously observed that reptarenavirus S and L segment combinations may vary between the tissues of an infected snake, leading to the hypothesis that the segment combination might contribute to tissue and/or species tropism. To test the hypothesis, we inoculated various cell lines derived from different tissues of several constrictor snake species with two samples containing multiple reptarenavirus segments (F15, two S and seven L segments; F17, one S and four L segments). We blind-passaged both virus samples five times in each cell line and monitored the presence of the segments in the supernatants through reverse transcription PCR. We also passaged the cells following the first inoculation with F17 and studied the segments present as above. The analysis revealed that some L segments were only present in supernatants with a specific S segment, suggesting preferred S and L segment pairs, thereby arguing against free reassortment of the segments. The results also showed that boa constrictor-derived cell lines supported reptarenavirus infection slightly better than pythonid-derived cell lines.