RT Journal Article SR Electronic(1) A1 Zhang, Zhidong A1 Murphy, Ciara A1 Quan, Melvyn A1 Knight, Jeanette A1 Alexandersen, SorenYR 2004 T1 Extent of reduction of foot-and-mouth disease virus RNA load in oesophageal–pharyngeal fluid after peak levels may be a critical determinant of virus persistence in infected cattle JF Journal of General Virology, VO 85 IS 2 SP 415 OP 421 DO https://doi.org/10.1099/vir.0.19538-0 PB Microbiology Society, SN 1465-2099, AB To investigate whether foot-and-mouth disease virus (FMDV) RNA loads in oesophageal–pharyngeal fluid (OP-fluid) in the early course of infection is related to the outcome of virus persistence, viral RNA in OP-fluid samples from cattle experimentally infected with FMDV type O was quantitatively analysed by using a quantitative real-time RT-PCR. Viral RNA was detected within 24 h post-infection (p.i.) in all infected animals. Rapid virus replication led to peak levels of viral RNA load by 30–53 h p.i., and then the load declined at various rates. In some animals (n=12, so-called non-carriers) viral RNA became undetectable between 7 and 18 days p.i. In contrast, in persistently infected animals (n=12, so-called carriers) viral RNA persisted in OP-fluid samples at detectable levels beyond 28 days p.i. Analysis of early viral decay/clearance and virus clearance half-life in OP-fluid samples showed that the extent of reduction of viral RNA in OP-fluid samples immediately following peak levels is a critical determinant of the outcome of FMDV persistence., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.19538-0