However, respiratory insufficiency is not associated with death of mice infected with Western equine encephalitis virus (WEEV), which suggests that respiratory insufficiency is the physiological mechanism of death for a subset of encephalitides, but not all. Since respiratory insufficiency is a good predictor as to which individuals may die, suppression of MV might be used as a trigger to employ therapies to prevent death, which otherwise might not be indicated. EMG of the diaphragm has been valuable in establishing the neurological cause of respiratory insufficiency. Selleckchem BMS754807 Early in development of the procedure, electrodes attached to near the predicted motor

plates of the diaphragm and exiting the dorsal skin of the animal allowed for measurements of EMG over time in alert, non-anesthetized hamsters (Morrey et al., 2010). This procedure is surgically involved, but has yielded data to indicate

that WNV-infected mice develop diaphragmatic EMG suppression as compared to sham-infected animals. The diaphragmatic EMG readout was further developed in anesthetized mice to eliminate variability of behavior in alert animals (Wang et al., 2013b). Bilateral vagotomy is performed on ventilated isoflorane-anesthetized mice to abolish mechanoreceptor feedback. In these mice, diaphragmatic EMG signals are not detected. The middle EMG tracing of each selleck inhibitor mouse in Fig. 5 shows the absence of diaphragmatic EMG signals in vagotomized mice infected with WNV, WEEV, and sham. When the anesthetized mice are then exposed to hypercapnia at 7% CO2, the chemoreceptor cells in the medulla oblongata signal innervation of the diaphragm and are detected by EMG (bottom tracings, Fig. 5). The WNV-infected mouse (#594) with confirmed respiratory

insufficiency as detected by plethysmography Adenosine does not show any EMG signal, as compared to sham- and WEEV-infected mice that had robust EMG signals of the diaphragm in response to hypercapnia. The loss of diaphragmatic EMGs for WNV is consistent with loss of plethysmography results (Fig. 4). Essentially, anesthetized WNV-, POWV-, and NSV-infected animals, but not WEEV-infected animals, are not able to neurologically compensated for hypercapnia (Morrey et al., 2012). Another respiratory neurological deficit in phrenic neurons is detected with the use of the same optogenetics transgenic mice expressing ChR2 in their spinal cords as employed to measure motor function deficits in Fig. 2. Since the ChR2 is expressed from the choline acetyltransferase promoter, the function of phrenic neurons in the cervical cord controlling the innervation of the diaphragm can be monitored in infected mice (Wang et al., 2013b). When the cervical cord (C4–5) neurons are illuminated with fiber optics, EMG activation can be detected in the diaphragms of sham-infected mouse #170 (Fig. 6).