A Novel Mycovirus Identified in Clinical Isolates of Cryptococcus neoformans
Mycoviruses are widespread throughout the fungal kingdom and are known to infect diverse fungal taxa including fungal species that are important plant and human pathogens. Although many mycoviruses have been found to have minimal effects on their host, several viruses have been found to modulate fungal physiology, and as a result impact fungal virulence. Screens for mycoviruses in clinically…
A previously unknown type of mycovirus has been discovered within six clinical isolates of Cryptococcus neoformans, a dangerous human pathogen responsible for cryptococcal meningitis. This opportunistic yeast causes life-threatening meningitis, a leading cause of death in individuals with weakened immune systems, particularly those with HIV/AIDS.
The researchers examined publicly available transcriptomic data of C. neoformans and found Totiviridae viral genomes in six of the isolates, all from HIV-positive patients suffering from cryptococcal meningitis. The presence of the virus was confirmed through reverse transcription PCR (RT-PCR) in three of these clinical isolates.
Further analysis of the viral genome revealed that it belongs to a single species of Totivirus, which exhibits all the typical characteristics of the Totiviridae family. This includes a distinct heptamer known as a slippery sequence and an RNA pseudoknot structure that is crucial for the programmed -1 ribosomal frameshifting necessary for the expression of the RNA-dependent RNA polymerase (RdRP).
The findings indicate the existence of a mycovirus that can infect C. neoformans, contributing to our understanding of the potential impact of mycoviruses on the pathogenicity of this human pathogen.
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