Complex interplay: The interactions between citrus tristeza virus and its host.

Citrus tristeza virus (CTV) is one of the largest and most economically important RNA viruses infecting plants. CTV's interactions with various citrus hosts can result in three diseases: quick decline, stem pitting, or seedling yellows. Studying CTV poses several challenges owing to its significant genetic diversity and the highly specific occurrence of disease symptoms when different genotypes infect different citrus hosts. Considerable progress has been made to functionally characterize the virus-host interactions involved in the induction of CTV's three diseases, revealing that the four CTV ORFs (p33, p18, p13 and p23) play significant roles in determining the pathogenicity of CTV infections. These ORFs are unique to CTV and are not conserved among other members of the family Closteroviridae. This minireview aims to capture the complexity of the factors that have been shown to be involved in CTV disease induction and highlights recent work that provides novel insights into this pathosystem.