Aquatic Macroinvertebrate Biodiversity Associated with Artificial Agricultural Drainage Ditches

Agricultural drainage channels and ditches are ubiquitous features in the lowland agricultural landscapes, built primarily to facilitate land drainage, irrigate agricultural crops and alleviate flood risk. Most drainage ditches are considered artificial waterbodies and are not typically included in routine monitoring programmes, and as a result the faunal and floral communities they support are poorly quantified. This paper characterizes the aquatic macroinvertebrate diversity (alpha, beta and gamma) of agricultural drainage ditches managed by an internal drainage board in Lincolnshire, UK. The drainage ditches support very diverse macroinvertebrate communities at both the site (alpha diversity) and landscape scale (gamma diversity) with the main arterial drainage ditches supporting greater numbers of taxa when compared to smaller ditches. Examination of the between site community heterogeneity (beta diversity) indicated that differences among ditches were high spatially and temporally. The results illustrate that both main arterial and side ditches make a unique contribution to aquatic biodiversity of the agricultural landscape. Given the need to maintain drainage ditches to support agriculture and flood defence measures, we advocate the application of principles from ‘reconciliation ecology’ to inform the future management and conservation of drainage ditches

Prevention of Cytotoxic T Cell Escape Using a Heteroclitic Subdominant Viral T Cell Determinant

High affinity antigen-specific T cells play a critical role during protective immune responses. Epitope enhancement can elicit more potent T cell responses and can subsequently lead to a stronger memory pool; however, the molecular basis of such enhancement is unclear. We used the consensus peptide-binding motif for the Major Histocompatibility Complex molecule H-2Kb to design a heteroclitic version of the mouse hepatitis virus-specific subdominant S598 determinant. We demonstrate that a single amino acid substitution at a secondary anchor residue (Q to Y at position 3) increased the stability of the engineered determinant in complex with H-2Kb. The structural basis for this enhanced stability was associated with local alterations in the pMHC conformation as a result of the Q to Y substitution. Recombinant viruses encoding this engineered determinant primed CTL responses that also reacted to the wildtype epitope with significantly higher functional avidity, and protected against selection of virus mutated at a second CTL determinant and consequent disease progression in persistently infected mice. Collectively, our findings provide a basis for the enhanced immunogenicity of an engineered determinant that will serve as a template for guiding the development of heteroclitic T cell determinants with applications in prevention of CTL escape in chronic viral infections as well as in tumor immunity

MHC-I peptides get out of the groove and enable a novel mechanism of HIV-1 escape

Major histocompatibility complex class I (MHC-I) molecules play a crucial role in immunity by capturing peptides for presentation to T cells and natural killer (NK) cells. The peptide termini are tethered within the MHC-I antigen-binding groove, but it is unknown whether other presentation modes occur. Here we show that 20% of the HLA-B*57:01 peptide repertoire comprises N-terminally extended sets characterized by a common motif at position 1 (P1) to P2. Structures of HLA-B*57:01 presenting N-terminally extended peptides, including the immunodominant HIV-1 Gag epitope TW10 (TSTLQEQIGW), showed that the N terminus protrudes from the peptide-binding groove. The common escape mutant TSNLQEQIGW bound HLA-B*57:01 canonically, adopting a dramatically different conformation than the TW10 peptide. This affected recognition by killer cell immunoglobulin-like receptor (KIR) 3DL1 expressed on NK cells. We thus define a previously uncharacterized feature of the human leukocyte antigen class I (HLA-I) immunopeptidome that has implications for viral immune escape. We further suggest that recognition of the HLA-B*57:01-TW10 epitope is governed by a 'molecular tension' between the adaptive and innate immune systems

Distinct Immunoglobulin Fc Glycosylation Patterns Are Associated with Disease Nonprogression and Broadly Neutralizing Antibody Responses in Children with HIV Infection

A prophylactic HIV vaccine would ideally induce protective immunity prior to sexual debut. Children develop broadly neutralizing antibody (bnAb) responses faster and at higher frequencies than adults, but little is known about the underlying mechanisms or the potential role of Fc-mediated effector functions in disease progression. We therefore performed systems immunology, with immunoglobulin profiling, on HIV-infected children with progressive and nonprogressive disease. Pediatric nonprogressors (PNPs) showed distinct immunoglobulin profiles with an increased ability to elicit potent Fc-mediated natural killer (NK)-cell effector functions. In contrast to previous reports in adults, both groups of children showed high levels of gp120-specific IgG Fc glycan sialylation compared to bulk IgG. Importantly, higher levels of Fc glycan sialylation were associated with increased bnAb breadth, providing the first evidence that Fc sialylation may drive affinity maturation of HIV-specific antibodies in children, a mechanism that could be exploited for vaccination strategies.IMPORTANCE To protect future generations against HIV, a vaccine will need to induce immunity by the time of sexual debut and hence requires immunization during childhood. Current strategies for a prophylactic HIV vaccine include the induction of a broadly neutralizing antibody response and the recruitment of potent effector functions of immune cells via the constant antibody Fc region. In this study, we show that nonprogressing HIV-infected children mounted antibody responses against HIV that were able to mediate potent Fc effector functions, which may contribute to the control of HIV replication. Children who had specific glycan structures on the Fc portion of antibodies against HIV were able to neutralize a broader range of HIV variants, providing evidence of a potential role of Fc glycovariation in the development of bnAbs against HIV. These findings complement our knowledge of the distinct immune landscape in early life that could be exploited in the development of vaccine strategies

The Role of Ciliated Protozoa in Pelagic Freshwater Ecosystems

The abundance and biomass of ciliates are both strongly related to lake trophic status as measured by chlorophyll a concentrations. Taxonomic replacements occur with increasing eutrophication such that large-bodied forms (predominantly oligotrichs) are progressively replaced by smaller-bodied ciliates (mainly scuticociliates). Highly acidic lakes display a more pronounced dominance of large-bodied forms when contrasted with less acidic lakes of comparable trophy. Community structure of ciliate populations is determined largely by lake trophy with acidic oligotrophic systems being characterized by reduced diversity and species richness compared with hypereutrophic systems. The temporal and spatial distribution of small ( \u3c 100 μm) ciliate populations is ascribed to lake thermal regimes which provide localized concentrations of food resources. Likewise, in extremely productive lakes, very large ( \u3e 100 μm) meroplanktonic ciliates enter the water column during midsummer after the development of thermal stratification and associated profundal deoxygenation. Laboratory studies indicate that large zooplankton (crustaceans) are capable of utilizing ciliates as a food source, but there is little direct evidence from field studies documenting this trophic link. Ciliates can be voracious grazers of both bacterioplankton and phytoplankton, and each species has a distinct range of preferred particle size which is a function of both mouth size and morphology. Myxotrophic ciliates may be important components in some plankton communities, particularly during periods of nutrient limitation or after their displacement from the benthos of eutrophic lakes. Evidence regarding the importance of planktonic ciliated protozoa in nutrient regeneration and as intermediaries in energy flow is discussed. © 1989 Springer-Verlag New York Inc