Vertebrates express three cytokine-inducible proteasome subunits that are incorporated in the place of their constitutively synthesized counterparts. There is increasing evidence that the set of peptides generated by proteasomes containing these subunits (immunoproteasomes) differs from that produced by standard proteasomes. In this study, we use mice lacking one of the immunoproteasome subunits (LMP2) to show that immunoproteasomes play an important role in establishing the immunodominance hierarchy of CD8+ T cells (TCD8+) responding to seven defined determinants in influenza virus. In LMP2−/− mice, responses to the two most dominant determinants drop precipitously, whereas responses to two subdominant determinants are greatly enhanced. Adoptive transfer experiments with naive normal and transgenic TCD8+ reveal that the reduced immunogenicity of one determinant (PA224–233) can be attributed to decreased generation by antigen presenting cells (APCs), whereas the other determinant (NP366–374) is less immunogenic due to alterations in the TCD8+ repertoire, and not, as reported previously, to the decreased capacity of LMP2−/− APCs to generate the determinant. The enhanced response to one of the subdominant determinants (PB1F262–70) correlates with increased generation by LMP2− /− virus–infected cells. These findings indicate that in addition to their effects on the presentation of foreign antigens, immunoproteasomes influence TCD8+ responses by modifying the repertoire of responding TCD8+.

Nasopharyngeal swabs (NPSs) are being widely used as specimens for multiplex real-time reverse transcription (RT)-PCR for respiratory virus detection. However, it remains unclear whether NPS specimens are optimal for all viruses targeted by multiplex RT-PCR. In addition, the procedure to obtain NPS specimens causes coughing in most patients, which possibly increases the risk of nosocomial spread of viruses. In this study, paired NPS and saliva specimens were collected from 236 adult male patients with suspected acute respiratory illnesses. Specimens were tested for 16 respiratory viruses by multiplex real-time RT-PCR. Among the specimens collected from the 236 patients, at least 1 respiratory virus was detected in 183 NPS specimens (77.5%) and 180 saliva specimens (76.3%). The rates of detection of respiratory viruses were comparable for NPS and saliva specimens (P ϭ 0.766). Nine virus species and 349 viruses were isolated, 256 from NPS specimens and 273 from saliva specimens (P ϭ 0.1574). Adenovirus was detected more frequently in saliva samples (P Ͻ 0.0001), whereas influenza virus type A and human rhinovirus were detected more frequently in NPS specimens (P ϭ 0.0001 and P ϭ 0.0289, respectively). The possibility of false-positive adenovirus detection from saliva samples was excluded by direct sequencing. In conclusion, neither of the sampling methods was consistently more sensitive than the other. We suggest that these cost-effective methods for detecting respiratory viruses in mixed NPS-saliva specimens might be valuable for future studies. KEYWORDS saliva, respiratory virus, RT-PCR, nasopharyngeal swab Detection of viral pathogens in respiratory illnesses can provide valuable information to direct the proper management of patients and to prevent nosocomial transmission. Although various traditional diagnostic methods, such as direct antigen assays and viral cultures, are used for respiratory virus (RV) detection, nucleic acid amplification tests (NAATs) are thought to be superior in many respects, including sensitivity, specificity, time to virus identification, and range of pathogens detected (1-3).It is generally thought that nasopharyngeal specimens are optimal for detecting RVs, particularly when conventional methods are used (4). Currently, for adult patients, multiplex real-time reverse transcription (RT)-PCR assays using nasopharyngeal swabs (NPSs) are widely applied. However, acquiring NPSs is not as easy as obtaining other types of specimens, such as saliva specimens; this may result in suboptimal specimens, particularly if specimens are obtained by inexperienced personnel. Moreover, the

Protein complexes of the 28-kDa proteasome activator (PA28) family activate the proteasome and may alter proteasome cleavage specificity. Initial investigations have demonstrated a role for the IFN-γ-inducible PA28α/β complex in Ag processing. Although the noninducible and predominantly nuclear PA28γ complex has been implicated in affecting proteasome-dependent signaling pathways, such as control of the mitotic cell cycle, there is no previous evidence demonstrating a role for this structure in Ag processing. We therefore generated PA28γ-deficient mice and investigated their immune function. PA28γ−/− mice display a slight reduction in CD8+ T cell numbers and do not effectively clear a pulmonary fungal infection. However, T cell responses in two viral infection models appear normal in both magnitude and the hierarchy of antigenic epitopes recognized. We conclude that PA28γ−/− mice, like PA28α−/−/β−/− mice, are deficient in the processing of only specific Ags.