Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Multigene DNA prime-boost vaccines for SHIV89.6P

We assessed four prime-boost vaccine regimens with a Gene Gun component for SHIV89.6P in Macaca nemestrina. A dosing experiment using beta-galactosidase plasmid showed that 30 or 45 shots per dose elicited higher titer antibody than smaller doses. For SHIV89.6P, we administered a six-plasmid vaccine capable of producing non-infectious virions in vivo in combination with either vaccinia recombinants or inactivated virus. DNA prime/vaccinia boost, or the reverse, elicited strong immune responses. The SHIV89.6P challenge virus was grown in M. nemestrina peripheral blood mononuclear cells and titered in vivo intrarectally. As has been observed for SHIV89.6P in M. mulatta, the infected M. nemestrina experienced rapid and severe loss of circulating CD4+ T cells. Vaccinated macaques were challenged three weeks after the last boost. DNA prime/vaccina boost or vaccina prime/DNA boost protected 11/12 animals from acute CD4+ T cell depletion and disease, while other regimens were not effective.     

DNA vaccine strategies: candidates for immune modulation and immunization regimens

DNA vaccine strategies can differ greatly, with significant effects on the outcome of immunization. In this article, we discuss plasmid design strategies and vaccine regimens. Effectiveness against a pathogen can be affected by the choice of antigen and inclusion of multiple antigens. Gene expression and the resulting immune response can be improved by gene modification and choice of promoters. In designing vaccine regimens, one must consider further dose, timing of doses, adjuvants, and routes of vaccination. Many vaccines are enhanced by combining DNA with other vaccines in "prime-boost" regimens, in which the second vaccine is often a recombinant viral vector or purified protein subunit. Prime-boost vaccines including DNA can elicit immune responses that differ in magnitude, quality, and balance of cellular and humoral responses from those elicited by single components and thus provide further enhancement for DNA immunizations.     

Extramedullary hematopoiesis in a case of benign mixed mammary tumor in a female dog: cytological and histopathological assessment

Backgroud  

Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.     

Antibody-dependent cellular cytotoxicity against primary HIV-infected CD4+ T cells is directly associated with the magnitude of surface IgG binding

Antibody (Ab)-dependent cellular cytotoxicity (ADCC) is thought to potentially play a role in vaccine-induced protection from HIV-1. The characteristics of such antibodies remain incompletely understood. Furthermore, correlates between ADCC and HIV-1 immune status are not clearly defined. We screened the sera of 20 HIV-1-positive (HIV-1(+)) patients for ADCC. Normal human peripheral blood mononuclear cells were used to derive HIV-infected CD4(+) T cell targets and autologous, freshly isolated, natural killer (NK) cells in a novel assay that measures granzyme B (GrB) and HIV-1-infected CD4(+) T cell elimination (ICE) by flow cytometry. We observed that complex sera mediated greater levels of ADCC than anti-HIV-1 envelope glycoprotein (Env)-specific monoclonal antibodies and serum-mediated ADCC correlated with the amount of IgG and IgG1 bound to HIV-1-infected CD4(+) T cells. No correlation between ADCC and viral load, CD4(+) T cell count, or neutralization of HIV-1(SF162) or other primary viral isolates was detected. Sera pooled from clade B HIV-1(+) individuals exhibited breadth in killing targets infected with HIV-1 from clades A/E, B, and C. Taken together, these data suggest that the total amount of IgG bound to an HIV-1-infected cell is an important determinant of ADCC and that polyvalent antigen-specific Abs are required for a robust ADCC response. In addition, Abs elicited by a vaccine formulated with immunogens from a single clade may generate a protective ADCC response in vivo against a variety of HIV-1 species. Increased understanding of the parameters that dictate ADCC against HIV-1-infected cells will inform efforts to stimulate ADCC activity and improve its potency in vaccinees.     

Factors associated with inadequate colorectal cancer screening with flexible sigmoidoscopy

Background and study aim: Inadequate colorectal cancer screening wastes limited endoscopic resources. We examined patients factors associated with inadequate flexible sigmoidoscopy (FSG) screening at baseline screening and repeat screening 3–5 years later in 10 geographically-dispersed screening centers participating in the ongoing Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Methods: A total of 64,554 participants (aged 55–74) completed baseline questionnaires and underwent FSG at baseline. Of these, 39,385 participants returned for repeat screening. We used logistic regression models to assess factors that are associated with inadequate FSG (defined as a study in which the depth of insertion of FSG was <50 cm or visual inspection was limited to <90% of the mucosal surface but without detection of a polyp or mass). Results: Of 7084 (11%) participants with inadequate FSG at baseline, 6496 (91.7%) had <50 cm depth of insertion (75.3% due to patient discomfort) and 500 (7.1%) participants had adequate depth of insertion but suboptimal bowel preparation. Compared to 55–59 year age group, advancing age in 5-year increments (odds ratios (OR) from 1.08 to 1.51) and female sex (OR = 2.40; 95% confidence interval (CI): 2.27–2.54) were associated with inadequate FSG. Obesity (BMI >30 kg/m²) was associated with reduced odds (OR = 0.67; 95% CI: 0.62–0.72). Inadequate FSG screening at baseline was associated with inadequate FSG at repeat screening (OR = 6.24; 95% CI: 5.78–6.75). Conclusions: Sedation should be considered for patients with inadequate FSG or an alternative colorectal cancer screening method should be recommended.     

Surface-Matrix Screening Identifies Semi-specific Interactions that Improve Potency of a Near Pan-reactive HIV-1-Neutralizing Antibody

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Selection pressure on HIV-1 envelope by broadly neutralizing antibodies to the conserved CD4-binding site

The monoclonal antibody (MAb) VRC01 was isolated from a slowly progressing HIV-1-infected donor and was shown to neutralize diverse HIV-1 strains by binding to the conserved CD4 binding site (CD4bs) of gp120. To better understand the virologic factors associated with such antibody development, we characterized HIV-1 envelope (Env) variants from this donor and five other donors who developed broadly neutralizing antibodies. A total of 473 env sequences were obtained by single-genome amplification, and 100 representative env clones were expressed and tested for entry and neutralization sensitivity. While VRC01 neutralizes about 90% of the genetically diverse heterologous HIV-1 strains tested, only selective archival Env variants from the VRC01 donor were sensitive to VRC01 and all of the Env variants derived from the donor plasma were resistant, indicating strong antibody-based selection pressure. Despite their resistance to this broadly reactive MAb that partially mimics CD4, all Env variants required CD4 for entry. Three other CD4bs MAbs from the same donor were able to neutralize some VRC01 escape variants, suggesting that CD4bs antibodies continued to evolve in response to viral escape. We also observed a relatively high percentage of VRC01-resistant Env clones in the plasma of four of five additional broadly neutralizing donors, suggesting the presence of CD4bs-directed neutralizing antibodies in these donors. In total, these data indicate that the CD4bs-directed neutralizing antibodies exert ongoing selection pressure on the conserved CD4bs epitope of HIV-1 Env.     

Sequential immunization with a subtype B HIV-1 envelope quasispecies partially mimics the in vivo development of neutralizing antibodies

A major goal of human immunodeficiency virus type 1 (HIV-1) vaccine efforts is the design of Envelope (Env)-based immunogens effective at eliciting heterologous or broad neutralizing antibodies (NAbs). We hypothesized that programming the B-cell response could be achieved by sequentially exposing the host to a collection of env variants representing the viral quasispecies members isolated from an individual that developed broad NAbs over time. This ordered vaccine approach (sequential) was compared to exposure to a cocktail of env clones (mixture) and to a single env variant (clonal). The three strategies induced comparable levels of the autologous and heterologous neutralization of tier 1 pseudoviruses. Sequential and mixture exposure to quasispecies led to epitope targeting similar to that observed in the simian-human immunodeficiency virus (SHIV)-infected animal from which the env variants were cloned, while clonal and sequential exposure led to greater antibody maturation than the mixture. Therefore, the sequential vaccine approach best replicated the features of the NAb response observed in that animal. This study is the first to explore the use of a collection of HIV-1 env quasispecies variants as immunogens and to present evidence that it is possible to educate the B-cell response by sequential exposure to native HIV-1 quasispecies env variants derived from an individual with a broadened NAb response.