Histopathological and virus-associated features of Boid Inclusion Body Disease in Boa constrictor

Boid inclusion body disease (BIBD) is a reptarenavirus-induced fatal disease of boid snakes that, while diagnosed with ease due to the pathognomonic intracytoplasmic inclusion bodies (IB), is not yet fully characterized pathomorphologically and with regards to its pathogenesis. The present study retrospectively investigated a random cohort of 50 captive male and female boa constrictors of variable age (neonate to 25 years) for histopathological changes and in situ viral protein (nucleoprotein, NP, and glycoprotein 2, GP2) expression patterns. IB formation and NP expression were scored semiquantitatively. The vast majority of snakes (42/50; 84%) exhibited histopathological changes; these mainly (39/42; 93%) represented inflammatory processes that most frequently affected the gastrointestinal tract. Overall, IB and NP scores were significantly higher in the more recent cases (2020-2025) compared to the older cases (2000-2003). NP scores did not differ between age groups or sex, but were lower in animals with clinical signs and higher in those with histopathological changes. No statistically significant association was found between NP scores and inflammatory processes, neither in general nor in individual organs. GP2 expression, as an indicator of virion assembly, was less consistent than NP expression and generally restricted to individual cells with and without IBs. There was no histological evidence of overt damage in infected cells. Jointly, the results indicate different phases of restrictive and systemic viral replication that are not directly associated with pathological processes and/or clinical signs.