
Caenorhabditis briggsae wild isolates exhibit natural variation in their susceptibility to two intestinal RNA viruses, Santeuil virus (SANTV) and Le Blanc virus (LEBV), with some strains showing specific resistance to one virus. The genetic basis of this variation was mapped to quantitative trait loci on different chromosomes.


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Antagonistic relationships such as host-virus interactions potentially lead to rapid evolution and specificity in interactions. The Orsay virus is so far the only horizontal virus naturally infecting the nematode C. elegans . In contrast, several related RNA viruses infect its congener C. briggsae , including Santeuil (SANTV) and Le Blanc (LEBV) viruses. Here we focus on the host’s intraspecific variation in sensitivity to these two intestinal viruses. Many temperate-origin C. briggsae strains, including JU1264 and JU1498, are sensitive to both, while many tropical strains, such as AF16, are resistant to both. Interestingly, some C. briggsae strains exhibit a specific resistance, such as the HK104 strain, specifically resistant to LEBV. The viral sensitivity pattern matches the strains’ geographic and genomic relationships. The heavily infected strains mount a seemingly normal small RNA response that is insufficient to suppress viral infection, while the resistant strains show no small RNA response, suggesting an early block in viral entry or replication. We use a genetic approach from the host side to map genomic regions participating in viral resistance polymorphisms. Using Advanced Intercrossed Recombinant Inbred Lines (RILs) between virus-resistant AF16 and SANTV-sensitive HK104, we detect Quantitative Trait Loci (QTLs) on chromosomes IV and III. Building RILs between virus-sensitive JU1498 and LEBV-resistant HK104 followed by bulk segregant analysis, we identify a chromosome II QTL. In both cases, further introgressions of the regions confirmed the QTLs. This diversity provides an avenue for studying virus entry, replication, and exit mechanisms, as well as host-virus specificity and the host response to a specific virus infection.

### Competing Interest Statement

The authors have declared no competing interest.

*   ### Abbreviations
    
    SANTV
    :   Santeuil virus
    LEBV
    :   Le Blanc virus
    ORV
    :   Orsay virus
    QTL
    :   quantitative trait locus
    RdRP
    :   RNA-dependent RNA polymerase
    IPR
    :   Intracellular pathogen response
    FISH
    :   fluorescent in situ hybridization
    RT-qPCR
    :   reverse transcription followed by quantitative polymerase chain reaction
    SNP
    :   single-nucleotide polymorphism
    LOD
    :   logarithm of the odds
    RIL
    :   recombinant inbred line
    NIL
    :   near isogenic line.

Natural variation in infection specificity of Caenorhabditis briggsae isolates by two RNA viruses

genetic-basis-of-intraspecific-variation-in-caenorhabditis-briggsae-susceptibility-to-two-intestinal-rna-viruses


Genetic Basis of Intraspecific Variation in Caenorhabditis briggsae Susceptibility to Two Intestinal RNA Viruses
