2.5 Mink
challenge assay
The SVV-CH-09-2018 strain was used for the challenge test. Mink (n=6)
weaned for approximately 60 days were observed for 1 week to ensure
they
were asymptomatic. SVV, FMDV, SVDV, VSV,
and pseudorabies virus were not
detected by the corresponding ELISA
and RT-PCR or PCR(Luis Gabriel Gimenez-Lirola et al., 2016). The mink
were divided into two groups, the 3 minks were in each group. The first
group was injected intraperitoneally with a 5 mL volume of strain
SVV-CH-09-2018 (1×109 median cell culture infective
dose [TCID50]/mL). The second group was inoculated with DMEM as a
negative control (NC). Both groups
were fed under the same conditions and in separate rooms. Strict
biosafety protocols were followed to avoid crossover contamination.
Clinical symptoms were monitored daily for 28 days. At 0, 3, 7, 14, 21,
or 28 days post-challenge (dpc), serum was collected from each animal,
and the anti-SVV neutralizing antibody titer was determined(Joshi,
Fernandes, et al., 2016). TaqMan real-time RT-PCR was used to detect
viral load(Dall Agnol et al., 2017) (J. Zhang et al., 2019). A standard
curve was generated by plotting the threshold values against serially
diluted plasmid DNA encoding the SVV VP1 gene fragment. At 28 dpc, the
mice were euthanized for pathological examination. The heart, spleen,
liver, kidney, lung, inguinal lymph nodes, and other organs were
collected for histopathological observation. TaqMan real-time RT-PCR was
used to detect mRNA viral titers in these organs.