Dicer is essential for plant, Caenorhabditis elegans, and Drosophila antiviral responses because of its role in generating small interfering RNA (siRNA) from viral genomes. We show that because of impaired miRNA production, mice with a variant Dicer1 allele (Dicer1(d/d)) were more susceptible to vesicular stomatitis virus (VSV) infection. We did not detect VSV genome-derived siRNA in wild-type cells or any alteration of interferon-mediated antiviral responses by Dicer1 deficiency. Rather, we found that host miR24 and miR93 could target viral large protein (L protein) and phosphoprotein (P protein) genes, and a lack of miR24 and miR93 was responsible for increased VSV replication in Dicer1(d/d) cells. Our data suggest that host miRNA can play a role in host interactions with viruses.

In 20-40% of cervical intra-epithelial neoplasia (CIN) and in 4-8% of cervical carcinoma tissue specimens, multiple HPV genotypes have been detected. Whole tissue section (WTS) PCR does not determine how the individual types relate causally to complex and multiple CIN. Our objective was to determine whether laser capture micro-dissection (LCM) with HPV PCR genotyping (LCM-PCR) could accurately recover type-specific HPV DNA from epithelial cells in individual areas of CIN and normal epithelium, and whether one or more viruses are present in one lesion. For that, histologically selected samples of CIN and normal epithelium were isolated by LCM and analysed by the SPF(10) PCR/LiPA(25) (version 1) HPV genotyping system for 25 HPV genotypes. HPV genotypes detected in 756 areas of CIN (grade 1, 2 or 3) by LCM-PCR were compared with results obtained by WTS-PCR in 60 cases (74 biopsies). We showed that when a single HPV type is detected by WTS-PCR, that type was almost always (94%; 29/31) recovered by LCM-PCR from CIN. When multiple HPV types were present by WTS-PCR, their distribution within histological sections could be mapped by LCM-PCR. Association of a single HPV type with a discrete area of CIN was found for 93% (372/399) of LCM fragments analysed by PCR. We found colliding CIN lesions associated with separate HPV types and only 62% (61/99) of HPV types detected by WTS-PCR were found in CIN by LCM-PCR. Therefore, the LCM-PCR technique was found very accurate for high-resolution HPV genotyping and for assigning an individual HPV type to an area of CIN. At LCM level, in cervical biopsy sections with multiple HPV infections, the relation between HPV types and CIN lesions is often complex. Almost every HPV type found in CIN by LCM-PCR is associated with a biological separate independent CIN lesion-one virus, one lesion.

We have previously shown that mutations of CD14 or TLR4 impair type I interferon (IFN) production and macrophage survival during infection with vesicular stomatitis virus (VSV). We now report that VSV glycoprotein G (gpG) is essential for the induction of a previously unrecognized CD14/TLR4-dependent response pathway in which the adapter TRAM has predominant importance, absent any need for MyD88 or Mal, and with only a partial requirement for TRIF. Downstream of TRAM, IRF7 activation leads to a type I IFN response. The pathway is utilized by myeloid dendritic cells (mDCs) and macrophages rather than plasmacytoid DCs. This new mode of TLR4 signal transduction, which does not stimulate NF-kappaB activation, reveals the importance of viral protein recognition by mDCs and shows that TLR4 can drive qualitatively different events within the cell in response to different ligands.

The activation of p38α, a MAPK family member, is associated with macrophage activation by microbial pattern molecules, such as LPS. The requirement of p38α in inflammatory responses has been shown in a number of studies using chemical inhibitors, though the inhibitors also inhibit p38β and perhaps some other enzymes. In this study, we used conditional knockout of p38α in macrophages to address the role of p38α in macrophage activation. We found that p38α deficiency causes a significant inhibition in the production of LPS-induced TNF-α, IL-12, and IL-18, but it has little or no effect on IL-6 or IFN-β production. Knockout of p38α in macrophages did not affect LPS-induced activation of the other major signaling pathways (NF-κB, Jnk, and Erk), nor did it affect the transcriptional activity of NF-κB. It had little inhibitory effect on LPS-induced AP-1 activity, but it significantly inhibited LPS-induced C/EBP-β and CREB activation, indicating that the role of p38α in cytokine production in macrophages is at least in part through its regulation of C/EBP-β and CREB activation. In addition, we also confirmed that p38α is important for phagocytosis of bacteria by macrophages. Our in vivo studies with two murine models showed that p38α is involved in sepsis. Collectively, our data demonstrate that p38α is an important player in inflammatory responses.

NCT00802464.