Interaction of classical swine fever virus with dendritic cells

Functional disruption of dendritic cells (DCs) is an important strategy for viral pathogens to evade host defences. Monocytotropic viruses such as classical swine fever virus (CSFV) could employ such a mechanism, since the virus can suppress immune responses and induce apoptosis without infecting lymphocytes. Here, CSFV was shown to infect and efficiently replicate in monocyte- and in bone marrow-derived DCs. Interestingly, the infected DCs displayed neither modulated MHC nor CD80/86 expression. Stimulation of DCs with IFN-/TNF- or polyinosinic¿polycytidylic acid (pIC) induced phenotypic maturation with increased MHC and CD80/86 expression, both with mock-treated and infected DCs. In addition, the T cell stimulatory capacity of CSFV-infected DCs was maintained both in a polyclonal T cell stimulation and in specific antigen-presentation assays, requiring antigen uptake and processing. Interestingly, similar to macrophages, CSFV did not induce IFN- responses in these DCs and even suppressed pIC-induced IFN- induction. Other cytokines including interleukin (IL)-6, IL-10, IL-12 and TNF- were not modulated. Taken together, these results demonstrated that CSFV can replicate in DCs and control IFN type I responses, without interfering with the immune reactivity. These results are interesting considering that DC infection with RNA viruses usually results in DC activation

Effects of overhead canopy on macroinvertebrate production in a Utah stream

1. Macroinvertebrate abundance and production were compared between an open and shaded site of a stream in the Wasatch Mountains, Utah. Mean biomass was significantly higher at the open site for midges (Chironomidae), 4.6x; Baetis bicaudatus, 5.7x; Baetis tricaudatus, 2.3x; Drunella coloradensis, 12x and Cinygmula sp., L6x. Abundance of most other macroinvertebrates (except black flies: Simuliidae) was also greater at the open site, but differences were not significant. Black fly biomass was 1.7x greater at the shaded site. 2. Seasonal production, estimated by the size-frequency and instantaneous growth rate methods, was greater at the open site than the shaded site for most taxa (except black flies) and reflected differences in standing crops between the sites rather than differences in rate of growth. Excluding black flies, production at the open site was twice as high as at the shaded site. 3. The greater abundance and production of most invertebrate taxa at the open site is probably associated with either higher quality food (algae and algal detritus), or a phototactic attraction to sunlit areas. 4. Sampling of large cobbles was an efficient method of sampling all taxa except Cinygmula sp. which was more abundant on smaller substrate particles