T-Cell Immune Responses Against Env from CRF12_BF and Subtype B HIV-1 Show High Clade-Specificity that Can Be Overridden by Multiclade Immunizations

BACKGROUND: The extreme genetic diversity of the human immunodeficiency virus type 1 (HIV-1) poses a daunting challenge to the generation of an effective AIDS vaccine. In Argentina, the epidemic is characterized by the high prevalence of infections caused by subtype B and BF variants. The aim of this study was to characterize in mice the immunogenic and antigenic properties of the Env protein from CRF12_BF in comparison with clade B, employing prime-boost schemes with the combination of recombinant DNA and vaccinia virus (VV) vectors. METHODOLOGY/PRINCIPAL FINDINGS: As determined by ELISPOT from splenocytes of animals immunized with either EnvBF or EnvB antigens, the majority of the cellular responses to Env were found to be clade-specific. A detailed peptide mapping of the responses reveal that when there is cross-reactivity, there are no amino acid changes in the peptide sequence or were minimal and located at the peptide ends. In those cases, analysis of T cell polifunctionality and affinity indicated no differences with respect to the cellular responses found against the original homologous sequence. Significantly, application of a mixed immunization combining both clades (B and BF) induced a broader cellular response, in which the majority of the peptides targeted after the single clade vaccinations generated a positive response. In this group we could also find significant cellular and humoral responses against the whole gp120 protein from subtype B. CONCLUSIONS/SIGNIFICANCE: This work has characterized for the first time the immunogenic peptides of certain EnvBF regions, involved in T cell responses. It provides evidence that to improve immune responses to HIV there is a need to combine Env antigens from different clades, highlighting the convenience of the inclusion of BF antigens in future vaccines for geographic regions where these HIV variants circulate

Impact of different cropping conditions and tillage practices on the soil fungal abundance of a Phaeozem luvico

Fungal diversity seems to be a good indicator of ecosystem disturbance and functioning. The purpose of this work was to quantify the fungal population as a sensitive indicator of the changes caused by stubble placement in two tillage systems: reduced tillage (RT) and conventional tillage (CT) with and without cropping. To this end, we determined the effect of soil disturbances such as N fertilization, tillage practice, and cropped area on the soil fungal communities of a Phaeozem luvico of the El Salado river basin (Argentina). Soil samples (at 0-10 cm depth) were collected from a field cultivated with wheat at post-harvest, before sowing and at tillering. The relative abundance of individuals of the fungal population was studied on Nash Snyder and Oxgall agar media after different treatments and assessed as colony forming units (CFU/gof soil). The diversity of the fungal population was studied by Shannon´s index (H). The tillage system showed a marked effect only at post-harvest and the number of propagules was highest under RT for both culture media. The largest values of H were found only at post-harvest when Oxgall agar was used. A significant decrease in the values of H was observed when CT and high fertilization was applied in the wheat cropped area. The relative abundance of individuals of the fungal population was different in soils under the different tillage practices

Respuesta de Stylosanthes guianensis Ciat 184 a la fertilización con una baja dosis de fósforo

El objetivo fue evaluar la respuesta sobre el rendimiento de MS de Stylosanthes guianensis a una baja dosis de fósforo. El diseño experimental fue bloques completos al azar, con cuatro repeticiones. Los tratamientos fueron PO y P 11kg ha, usando superfosfato triple, aplicado al voleo e incorporado en el momento de la siembra. El suelo pertenece a la Serie Ensenada Grande, clasificado como psamaquent típico. Las semillas se escarificaron, se inocularon y se sembró a una densidad de 3 kg ha. Se evaluó vigor de plantas, porcentaje de cobertura, rendimiento mensual y porcentaje de materia seca (MS). Se determinó rendimiento acumulado, contenido de P, K y proteína cruda. Los datos se analizaron con varianza y las diferencias entre medias con Tukey (p< 0,05). Los valores de cobertura fueron superiores en las parcelas fertilizadas (74% vs. 45%). El porcentaje de MS fue menor en las plantas fertilizadas (21,8% vs. 24,6%). El fósforo incrementó en un 100% la producción acumulada, siendo las diferencias estadísticamente significativas (p< 0,05). Los contenidos de P fueron diferentes entre los tratamientos. En un suelo arenoso con muy baja disponibilidad de P, una dosis baja de P permitió incrementar el rendimiento de MS y el contenido de P en planta en esta especi