PHOX2B and infection: Furthermore, there was no difference in the total number of Nmb cells in RTN between 2 and 4 weeks post infection for both NT-shRNA (week 2: 286±10.4; week 4: 294.9±52.8, p=0.783) and PHOX2B-shRNA rats (week 2: 218.8±7.8; week 4: 249.5±33,9, p=0.118), suggesting that the progressive PHOX2B knockdown was specific for PHOX2B-shRNA treatment and it was not accompanied by an increased cell death beyond the first 2 weeks.