Autophagy-dependent viral recognition by plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) detect viruses in the acidified endosomes by means of Toll-like receptors (TLRs). Yet, pDC responses to certain single-stranded RNA (ssRNA) viruses occur only after live viral infection. We present evidence here that the recognition of such viruses by TLR7 requires transport of cytosolic viral replication intermediates into the lysosome by the process of autophagy. In addition, autophagy was found to be required for the production of interferon-alpha by pDCs. These results support a key role for autophagy in mediating ssRNA virus detection and interferon-alpha secretion by pDCs and suggest that cytosolic replication intermediates of viruses serve as pathogen signatures recognized by TLR7.     

Coordination of early protective immunity to viral infection by regulatory T cells

Suppression of immune responses by regulatory T cells (Tregs) is thought to limit late stages of pathogen-specific immunity as a means of minimizing associated tissue damage. We examined a role for Tregs during mucosal herpes simplex virus infection in mice, and observed an accelerated fatal infection with increased viral loads in the mucosa and central nervous system after ablation of Tregs. Although augmented interferon production was detected in the draining lymph nodes (dLNs) in Treg-deprived mice, it was profoundly reduced at the infection site. This was associated with a delay in the arrival of natural killer cells, dendritic cells, and T cells to the site of infection and a sharp increase in proinflammatory chemokine levels in the dLNs. Our results suggest that Tregs facilitate early protective responses to local viral infection by allowing a timely entry of immune cells into infected tissue.     

Determination of the potential for development of bacterial soft rot of potatoes

A method has been devised for assessing the potential hazard of soft rot development in potatoes. Tubers are placed in a mist chamber at 20 C (68F), a film of water is maintained on the tuber, and the extent of decay is assessed after 5 days. The soft rot potential determined in this way is intended as apractical indication of potential storage hazard, reflecting the overall effect of the various factors leading to bacterial decay. Tubers that had passed through a flume system and a rinsing spray in a commercial packing plant had a greater decay potential, even after passage through a hot-air dryer, than unwashed tubers. Differences in decay potential could be demonstrated between tubers that had been mechanically harvested and loaded into storage bins and those that had been harvested manually. In addition to the effect of mechanical damage and of passage through flumes, the decay potential was probably affected by the inoculum level ofErwinia carotovora. Pectolytic clostidia were also usually present in tubers rotting in mist chambers, and are probably involved in the decay.