Fig 1.
Hemorrhagic lesions in the olfactory epithelium of CHIKV infected IRF3/7-/- mice.
(A, C, E) H&E of the head of IRF3/7-/- mouse day 5 post CHIKV infection and (B, D, F) H&E of the head of a control uninfected IRF3/7-/- mouse; T—turbinate bones, arrows—red blood cells, NC—nasal cavity. (A) Low magnification image showing extensive red blood cells and mucous exudates (pink staining material) in the nasal cavities. (*—large foci of vacuolization in the olfactory bulb). (B) The same region and magnification as in A for an uninfected mouse. (C) Medium magnification image showing breaches in the olfactory epithelium (dotted white circles). (D) The same region and magnification as in C for an uninfected mouse. (E) High magnification image of a lesion in the olfactory epithelium showing pyknotic nuclei (white arrow heads) and some neutrophils (black arrow head). (F) The same region and magnification as in E for an uninfected mouse.
Fig 2.
Virus in oral cavity washings, vaginal washings and urine of CHIKV-infected IRF3/7-/- mice.
Mice were infected with CHIKV i.p. (n = 9) and when clinical symptoms of hypovolemic shock became apparent (indicating onset of hemorrhagic manifestations) [6], mouth washings (Oral cavity), vaginal washings (Vagina) and urine (where possible), were collected and viral titers determined and expressed as log10CCID50/ml of washing medium on the indicated day (which is indicated in brackets below the titer Figs, respectively). † day when mouse was euthanized. NT–not tested.
Fig 3.
CHIKV infection via intranasal and oral routes.
CHIKV was inoculated via pipette into the nose or mouth of restrained IRF3/7-/- and C57BL/6 mice (n = 3 per group, 12 mice total). Viraemia was monitored as described, with 2 log10CCID50 the limit of detection [6]. †—mouse euthanized.
Table 1.
Mouse-to-mouse transmission of CHIKV.
Donor mice were infected with CHIKV and were then housed in the same cage as naïve Recipient mice. Infection of Recipient IRF3/7-/- mice become apparent at the indicated times (Column 3) by onset of clinical symptoms (hunching, ruffled fur, swollen feet) indicating onset of CHIKV-induced hemorrhagic shock [6]. Samples for viraemia and/or RT-PCR were taken on the days indicated in Column 3.
Table 2.
Presence of CHIKV RNA and infectious CHIKV in the saliva of CHIKV infected cynomolgus macaques.
Monkeys A and B were infected with 106 PFU and monkeys C-F with 4 x 103 PFU of CHIKV. Viral RNA copies were determined by quantitative real time RT-PCR; (the full data set for animals C-F is graphed in Fig C in S1 File. Infectious virus titers were determined by CCID50 assay using BHK-21 cells or PFU assay using Vero cells. Day 2 usually represents peak viraemia [16]. ND—not detected. NT—not tested. 1 Blood noted in sample. Where PFU and CCID50 values were determined, tests were performed at different times with different storage periods.
Fig 4.
Presence of CHIKV RNA and infectious virus in the saliva of acute CHIKV infected patients.
All patients were negative for dengue. Symptoms, manifestations and comorbidities at time of saliva collection. 1 H–Hospital study, C–Cohort study. 2 CHIKV detected in saliva by TaqMan RT-PCR. 3 Saliva was incubated with Vero cells, and TaqMan RT-PCR was used to confirm CHIKV in cultures showing cytopathic effect. NT–not tested.