3.3 Dose response curve
We expected that DDVax would not be found at significant levels outside
mosquito midguts, as described in previous reports of plaque assays for
infectious virus(Crabtree et al., 2012). However, our challenge
experiments showed unexpectedly high levels of DDVax RNA-positive,
CPE-negative saliva samples (Table 2, Table S1, Figure 1B). We
hypothesized that the high levels of DDVax viral RNA in saliva may have
been due to the high viral titer of the infectious bloodmeal (Figure
1A), which could have overwhelmed natural infection barriers. Therefore,
to confirm that viral RNA positivity varied as a function of bloodmeal
titer, a second DDVax challenge was performed with Cx. tarsalismosquitoes, using virus serial dilutions. Bloodmeals containing 6.2,
4.5, and 3.5 log10 PFU/ml DDVax were provided. There was
a trend for reduction of viral RNA in bodies, legs/wings, and saliva
samples as the bloodmeal titer decreased (Table S2, Figure S3). However,
strikingly, there was still detectable viral RNA in salivary
expectorants with all viral dilutions, including the 3.5
log10 PFU/ml virus meal.