The potential of remote sensing of cover crops to benefit sustainable and precision fertilization.

Cover crops and precision fertilization are two core strategies to advance sustainable agriculture. Based on a review of proven achievements in remote sensing of vegetation, a novel approach is proposed to use remote-sensing of cover crops to map soil nutrient availability and to produce prescription maps for precision basal fertilization prior to sowing the following cash crop. The first goal of this manuscript is to introduce the concept of using remote-sensing of cover crops as 'reflectors' or 'bio-indicators' of soil nutrient availability. This concept has two components: 1. mapping nitrogen availability using remote-sensing of cover crops; 2. using remotely-detected visual symptoms of cover crops' nutrient deficiencies to guide sampling schemes. The second goal was to describe two case studies that initially evaluated the feasibility of this concept in a 20 ha field. In the first case study, cover crops mixtures containing legumes and cereals were sown during two seasons in soils with different nitrogen levels. Cereals dominated the mixture when soil nitrogen levels were low, while legumes dominated when levels were high. Plant height and texture analysis derived from UAV-RGB-images were used to measure differences between the dominant species as an indicator of soil nitrogen availability. In the second case study, in an oat cover crop, three different appearances of visual symptoms (phenotypes) were observed throughout the field, and laboratory analysis showed they significantly differed in their nutrient levels. Spectral vegetation indices and plant height derived from UAV-RGB-images were analyzed by a multi-stage classification procedure to differentiate between the phenotypes. The classified product was interpreted and interpolated to generate a high-resolution map showing nutrient uptake for the whole field. The suggested concept essentially elevates the services cover crops can provide to benefit sustainable agriculture if incorporated with remote-sensing. The potentials, limitations and open questions concerning the suggested concept are discussed.

Plans of mice and men: from bench science to science policy.

The transition from bench science to science policy is not always a smooth one, and my journey stretched as far as the unemployment line to the hallowed halls of the U.S. Capitol. While earning my doctorate in microbiology, I found myself more interested in my political activities than my experiments. Thus, my science policy career aspirations were born from merging my love of science with my interest in policy and politics. After receiving my doctorate, I accepted the Henry Luce Scholarship, which allowed me to live in South Korea for 1 year and delve into the field of science policy research. This introduction into science policy occurred at the South Korean think tank called the Science and Technology Policy Institute (STEPI). During that year, I used textbooks, colleagues, and hands-on research projects as my educational introduction into the social science of science and technology decision-making. However, upon returning to the United States during one of the worst job markets in nearly 80 years, securing a position in science policy proved to be very difficult, and I was unemployed for five months. Ultimately, it took more than a year from the end of the Luce Scholarship to obtain my next science policy position with the American Society for Microbiology Congressional Fellowship. This fellowship gave me the opportunity to work as the science and public health advisor to U.S. Senator Harry Reid. While there were significant challenges during my transition from the laboratory to science policy, those challenges made me tougher, more appreciative, and more prepared to move from working at the bench to working in the field of science policy.

Some attenuated variants of vesicular stomatitis virus show enhanced oncolytic activity against human glioblastoma cells relative to normal brain cells.

Vesicular stomatitis virus (VSV) has been shown in laboratory studies to be effective against a variety of tumors, including malignant brain tumors. However, attenuation of VSV may be necessary to balance the potential toxicity toward normal cells, particularly when targeting brain tumors. Here we compared 10 recombinant VSV variants resulting from different attenuation strategies. Attenuations included gene shifting (VSV-p1-GFP/RFP), M protein mutation (VSV-M51), G protein cytoplasmic tail truncations (VSV-CT1/CT9), G protein deletions (VSV-dG-GFP/RFP), and combinations thereof (VSV-CT9-M51). Using in vitro viability and replication assays, the VSV variants were grouped into three categories, based on their antitumor activity and non-tumor-cell attenuation. In the first group, wild-type-based VSV-G/GFP, tumor-adapted VSV-rp30, and VSV-CT9 showed a strong antitumor profile but also retained some toxicity toward noncancer control cells. The second group, VSV-CT1, VSV-dG-GFP, and VSV-dG-RFP, had significantly diminished toxicity toward normal cells but showed little oncolytic action. The third group displayed a desired combination of diminished general toxicity and effective antitumor action; this group included VSV-M51, VSV-CT9-M51, VSV-p1-GFP, and VSV-p1-RFP. A member of the last group, VSV-p1-GFP, was then compared in vivo against wild-type-based VSV-G/GFP. Intranasal inoculation of young, postnatal day 16 mice with VSV-p1-GFP showed no adverse neurological effects, whereas VSV-G/GFP was associated with high lethality (80%). Using an intracranial tumor xenograft model, we further demonstrated that attenuated VSV-p1-GFP targets and kills human U87 glioblastoma cells after systemic application. We concluded that some, but not all, attenuated VSV mutants display a favorable oncolytic profile and merit further investigation.

Immunogenicity of viral vector, prime-boost SIV vaccine regimens in infant rhesus macaques: attenuated vesicular stomatitis virus (VSV) and modified vaccinia Ankara (MVA) recombinant SIV vaccines compared to live-attenuated SIV.

In a previously developed infant macaque model mimicking HIV infection by breast-feeding, we demonstrated that intramuscular immunization with recombinant poxvirus vaccines expressing simian immunodeficiency virus (SIV) structural proteins provided partial protection against infection following oral inoculation with virulent SIV. In an attempt to further increase systemic but also local antiviral immune responses at the site of viral entry, we tested the immunogenicity of different orally administered, replicating vaccines. One group of newborn macaques received an oral prime immunization with a recombinant vesicular stomatitis virus expressing SIVmac239 gag, pol and env (VSV-SIVgpe), followed 2 weeks later by an intramuscular boost immunization with MVA-SIV. Another group received two immunizations with live-attenuated SIVmac1A11, administered each time both orally and intravenously. Control animals received mock immunizations or non-SIV VSV and MVA control vectors. Analysis of SIV-specific immune responses in blood and lymphoid tissues at 4 weeks of age demonstrated that both vaccine regimens induced systemic antibody responses and both systemic and local cell-mediated immune responses. The safety and immunogenicity of the VSV-SIVgpe+MVA-SIV immunization regimen described in this report provide the scientific incentive to explore the efficacy of this vaccine regimen against virulent SIV exposure in the infant macaque model.

Vesicular stomatitis virus genomic RNA persists in vivo in the absence of viral replication.

Our previous studies using intranasal inoculation of mice with vesicular stomatitis virus (VSV) vaccine vectors showed persistence of vector genomic RNA (gRNA) for at least 60 days in lymph nodes in the absence of detectable infectious virus. Here we show high-level concentration of virus and gRNA in lymph nodes after intramuscular inoculation of mice with attenuated or single-cycle VSV vectors as well as long-term persistence of gRNA in the lymph nodes. To determine if the persistence of gRNA was due to ongoing viral replication, we developed a tagged-primer approach that was critical for detection of VSV mRNA specifically. Our results show that VSV gRNA persists long-term in the lymph nodes while VSV mRNA is present only transiently. Because VSV transcription is required for replication, our results indicate that persistence of gRNA does not result from continuing viral replication. We also performed macrophage depletion studies that are consistent with initial trapping of VSV gRNA largely in lymph node macrophages and subsequent persistence elsewhere in the lymph node.

Viral strategies for studying the brain, including a replication-restricted self-amplifying delta-G vesicular stomatis virus that rapidly expresses transgenes in brain and can generate a multicolor golgi-like expression.

Viruses have substantial value as vehicles for transporting transgenes into neurons. Each virus has its own set of attributes for addressing neuroscience-related questions. Here we review some of the advantages and limitations of herpes, pseudorabies, rabies, adeno-associated, lentivirus, and others to study the brain. We then explore a novel recombinant vesicular stomatitis virus (dG-VSV) with the G-gene deleted and transgenes engineered into the first position of the RNA genome, which replicates only in the first brain cell infected, as corroborated with ultrastructural analysis, eliminating spread of virus. Because of its ability to replicate rapidly and to express multiple mRNA copies and additional templates for more copies, reporter gene expression is amplified substantially, over 500-fold in 6 hours, allowing detailed imaging of dendrites, dendritic spines, axons, and axon terminal fields within a few hours to a few days after inoculation. Green fluorescent protein (GFP) expression is first detected within 1 hour of inoculation. The virus generates a Golgi-like appearance in all neurons or glia of regions of the brain tested. Whole-cell patch-clamp electrophysiology, calcium digital imaging with fura-2, and time-lapse digital imaging showed that neurons appeared physiologically normal after expressing viral transgenes. The virus has a wide range of species applicability, including mouse, rat, hamster, human, and Drosophila cells. By using dG-VSV, we show efferent projections from the suprachiasmatic nucleus terminating in the periventricular region immediately dorsal to the nucleus. DG-VSVs with genes coding for different color reporters allow multicolor visualization of neurons wherever applied.

SARS vaccine based on a replication-defective recombinant vesicular stomatitis virus is more potent than one based on a replication-competent vector.

A SARS vaccine based on a live-attenuated vesicular stomatitis virus (VSV) recombinant expressing the SARS-CoV S protein provides long-term protection of immunized mice from SARS-CoV infection (Kapadia, S.U., Rose, J. K., Lamirande, E., Vogel, L., Subbarao, K., Roberts, A., 2005. Long-term protection from SARS coronavirus infection conferred by a single immunization with an attenuated VSV-based vaccine. Virology 340(2), 174-82.). Because it is difficult to obtain regulatory approval of vaccine based on live viruses, we constructed a replication-defective single-cycle VSV vector in which we replaced the VSV glycoprotein (G) gene with the SARS-CoV S gene. The virus was only able to infect cells when pseudotyped with the VSV G protein. We measured the effectiveness of immunization with the single-cycle vaccine in mice. We found that the vaccine given intramuscularly induced a neutralizing antibody response to SARS-CoV that was approximately ten-fold greater than that required for the protection from SARS-CoV infection, and significantly greater than that generated by the replication-competent vector expressing SARS-CoV S protein given by the same route. Our results, along with earlier studies showing potent induction of T-cell responses by single-cycle vectors, indicate that these vectors are excellent alternatives to live-attenuated VSV.

Replication and propagation of attenuated vesicular stomatitis virus vectors in vivo: vector spread correlates with induction of immune responses and persistence of genomic RNA.

Live-attenuated vesicular stomatitis virus (VSV) vectors expressing foreign antigens induce potent immune responses and protect against viral diseases in animal models. Highly attenuated (VSV-CT1) or single-cycle VSV (VSVDeltaG) vectors induce immune responses lower than those generated by attenuated wild-type VSV vectors when given intranasally. We show here that reduced spread of the more highly attenuated or single-cycle vectors to other organs, including lymph nodes, correlates with the reduction in the immune responses. A reverse transcription, real-time PCR assay for VSV genomic RNA (gRNA) sequences showed long-term persistence of gRNA from replicating vectors in lymph nodes, long after viral clearance. Such persistence may be important for induction of potent immune responses by VSV vectors.