Susceptibility of Xenopus laevis tadpoles to infection by the ranavirus Frog-Virus 3 correlates with a reduced and delayed innate immune response in comparison with adult frogs

• Published in: Virology (New York, N.Y.) Vol. 432; no. 2; pp. 435 - 443
• Main Authors: De Jesús Andino, Francisco, Chen, Guangchun, Li, Zhenghui, Grayfer, Leon, Robert, Jacques
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25.10.2012
• Subjects: Amphibian; Animals; Anti-viral immunity; DNA Virus Infections - immunology; DNA Virus Infections - veterinary; DNA Virus Infections - virology; Gene Expression Profiling; Gene Expression Regulation - immunology; Immunity, Innate; Infectious Disease; Innate immunity; Larva - immunology; Larva - virology; Leukocytes - immunology; Ranavirus - growth & development; Ranavirus - pathogenicity; Time Factors; Viral infection; Xenopus laevis - growth & development; Xenopus laevis - immunology; Xenopus laevis - virology; one-way analysis of variance; FV3; intraperitoneal injection; RV; MOI; post-infection; Frog Virus 3; Qpcr; Innate immunity; i.p; p.i; quantitative real-time PCR; Viral infection; Anti-viral immunity; immediate-early; multiplicity of infection; ANOVA; plaque forming units; Ranavirus; IE; dpi; days post-infection; PFU; Amphibian
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2012.07.001

Abstract Xenopus laevis adults mount effective immune responses to ranavirus Frog Virus 3 (FV3) infections and clear the pathogen within 2–3 weeks. In contrast, most tadpoles cannot clear FV3 and succumb to infections within a month. While larval susceptibility has been attributed to ineffective adaptive immunity, the contribution of innate immune components has not been addressed. Accordingly, we performed a comprehensive gene expression analysis on FV3-infected tadpoles and adults. In comparison to adults, leukocytes and tissues of infected tadpoles exhibited modest (10–100 time lower than adult) and delayed (3 day later than adult) increase in expression of inflammation-associated (TNF-α, IL-1β and IFN-γ) and antiviral (Mx1) genes. In contrast, these genes were readily and robustly upregulated in tadpoles upon bacterial stimulation. Furthermore, greater proportions of larval than adult PLs were infected by FV3. Our study suggests that tadpole susceptibility to FV3 infection is partially due to poor virus-elicited innate immune responses.