?:abstract
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Previously, the M1058L and S1060A amino acid mutations in the spike protein of feline coronavirus (FCoV) have been shown to distinguish feline infectious peritonitis virus (FIPV) from feline enteric coronavirus (FECV) in >95% of serotype I FCoV (FCoVI)-infected cases, serving as potential FIP diagnostic markers However, the finding is recently challenged by the demonstration that these markers are merely indicative of systemic spread of FCoV from the intestine, rather than a mutated FIPV with the potential to cause FIP The aim of this study is to design a modified spike mutation-detection nested RT-PCR to distinguish FIPV from FECV in formalin-fixed and paraffin-embedded (FFPE) tissues from cats confirmed with FIP and controls While none in the control group was tested positive by the nRT-PCR, FCoVI RNA was detected in 20 of 23 FIP cases Of the positive samples, 19/20 (95%) FIP cats bore one of the two mutations in the spike gene The sensitivity and specificity of this test reached 87% (95% CI: 65-97) and 100% (95% CI: 82-100), respectively The high positive predictive values of 100% (95% CI: 80-100) and the negative predictive values of 88% (95% CI: 68-97) were determined By using the conventional nested RT-PCR method in FFPE tissue, we revealed the spike gene-mutated FCoVs could be detected in FFPE tissues from FIP-confirmed cats, but could not be amplified from cats without FIP Our result supports that detection of the two critical mutations correlates the presence of serotype I FIPV in FIP cats
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