Relationship between sugarcane rust severity and soil properties in louisiana

ABSTRACT The extent of spatial and temporal variability of sugarcane rust (Puccinia melanocephala) infestation was related to variation in soil properties in five commercial fields of sugarcane (interspecific hybrids of Saccharum spp., cv. LCP 85-384) in southern Louisiana. Sugarcane fields were grid-soil sampled at several intensities and rust ratings were collected at each point over 6 to 7 weeks. Soil properties exhibited significant variability (coefficients of variation = 9 to 70.1%) and were spatially correlated in 39 of 40 cases with a range of spatial correlation varying from 39 to 201 m. Rust ratings were spatially correlated in 32 of 33 cases, with a range varying from 29 to 241 m. Rust ratings were correlated with several soil properties, most notably soil phosphorus (r = 0.40 to 0.81) and soil sulfur (r = 0.36 to 0.68). Multiple linear regression analysis resulted in coefficients of determination that ranged from 0.22 to 0.73, and discriminant analysis further improved the overall predictive ability of rust models. Finally, contour plots of soil properties and rust levels clearly suggested a link between these two parameters. These combined data suggest that sugarcane growers that apply fertilizer in excess of plant requirements will increase the incidence and severity of rust infestations in their fields.     

Comment on "Large-scale sequence analysis of avian influenza isolates"

Obenauer et al. (Research Articles, 17 March 2006, p. 1576) reported that the influenza A virus PB1-F2 gene is evolving under strong positive selection, as documented by an extremely high ratio of the number of nonsynonymous nucleotide substitutions to the number of synonymous substitutions (dN/dS). However, we show that this observation is likely to be an artifact related to the location of PB1-F2 in the +1 reading frame of the PB1 gene.     

Serological and molecular evidence of exposure to arthropod-borne organisms in cats from northeastern Spain

One hundred sixty-eight cat sera from Spain were tested for IgG antibodies to Rickettsia conorii (Rc), Ehrlichia canis (Ec), Anaplasma phagocytophilum (Ap) and Bartonella henselae (Bh) antigens using IFA and for FeLV antigen and FIV antibody by ELISA. For 47 whole blood samples, PCR testing was performed for Rickettsia, Ehrlichia and Bartonella. Seroprevalences were: Bh (71.4%), Rc (44%), Ec (11.3%), FeLV (8.5%), FIV (7.4%) and Ap (1.8%). Bh antibodies were associated with seroreactivity to both Ec and Rc antigens. FIV antibodies were associated with illness and cats older than 2 years. Bartonella henselae and B. clarridgeiae (Bcl) DNA was amplified from seven and one sample, respectively.     

Host and bacterial factors in listeriosis pathogenesis

Members of the Genus Listeria are ubiquitous environmental saprophytic microorganisms. If ingested they can cause a severe disseminated disease (listeriosis) that has a high mortality rate, the highest of any food-borne pathogen, even with antibiotic therapy. Central to the high mortality rate is the hallmark characteristic of the microorganism to grow intracellularly. The presence of listeriae in food processing plants has resulted in many outbreaks of human disease and large scale recalls of processed foods. Despite the ubiquity of the microorganism, the actual disease rate (those animals showing disease signs over those exposed) is quite low and disease is almost always associated with an underlying predisposition (pregnancy being the most common in otherwise normal individuals). There are many features of the pathogenesis of listeriosis that have remained mysterious despite the extensive use of the microorganism in the study of cell-mediated immunity and intracellular growth. Informational advances such as the sequence of the mouse and listerial genomes, and technical advances such as the discovery of listeria-susceptible mouse strains, may renew interest in the study of the natural pathogenesis of the disease. This may be further facilitated by studies that employ the natural inoculation route and mimic common predisposing conditions witnessed in victims of natural outbreaks.     

A serological study of exposure to arthropod-borne pathogens in dogs from northeastern Spain

There is limited information regarding the prevalence of many vector borne pathogens in Europe and especially in Spanish dogs. We investigated 206 sick and 260 clinically healthy dogs from three different regions in northeastern Spain for antibodies to Rickettsia conorii (Rc), Ehrlichia canis (Ec), Anaplasma phagocytophilum (Ap), Bartonella henselae (Bh), Bartonella vinsonii subsp. berkhoffii (Bvb), Leishmania infantum (Li) and Borrelia burgdorferi (Bb) and for antigen of Dirofilaria immitis (Di). Total prevalences were the following: Rc (56.4%), Li (30%), Ec (16.7%), Bh (16.8%), Ap (11.5%), Bvb (1.07%), Di (0.6%) and Bb (0.6%). Seroprevalences for Rc, Ec, Ap, Bh, and Bvb and Bb and Di antigens were similar among the three different study sites. The Ec seroprevalence, as determined by Snap 3DX, was statistically lower in dogs from Mallorca (0%) than Tarragona (16%) and Barcelona (5%) (P < 0.0001). Detection of Rc antibodies was associated with seroreactivity to Ec and Ap antigens (P = 0.018 and P = 0.002, respectively). IFA Ec antibodies were associated with Ap seroreactivity (P < 0.0001). There was no association between the clinical status, sex, time of the year when samples were collected, life-style or exposure to fleas or ticks and a positive test result for Ec, Bh, Bvb, or Bb antibodies or Di antigens. Li seroreactivity was associated with illness and living outdoors (P < 0.0001, P = 0.029; respectively), Rc seroreactivity with the male gender (P = 0.028) and Ap seroreactivity with living outdoors (P = 0.045). This study indicates that exposure to Rc, Li, Ec or related Ehrlichia spp., Bh and Ap or a related spp., is common whereas Di, Bb and Bvb is uncommon among dogs from the Mediterranean basin. We also provide serological data that suggests the existence of a novel Ehrlichia species on Mallorca island.     

Prions in skeletal muscles of deer with chronic wasting disease

The emergence of chronic wasting disease (CWD) in deer and elk in an increasingly wide geographic area, as well as the interspecies transmission of bovine spongiform encephalopathy to humans in the form of variant Creutzfeldt Jakob disease, have raised concerns about the zoonotic potential of CWD. Because meat consumption is the most likely means of exposure, it is important to determine whether skeletal muscle of diseased cervids contains prion infectivity. Here bioassays in transgenic mice expressing cervid prion protein revealed the presence of infectious prions in skeletal muscles of CWD-infected deer, demonstrating that humans consuming or handling meat from CWD-infected deer are at risk to prion exposure.     

Long-term transmission of defective RNA viruses in humans and Aedes mosquitoes

In 2001, dengue virus type 1 (DENV-1) populations in humans and mosquitoes from Myanmar acquired a stop-codon mutation in the surface envelope (E) protein gene. Within a year, this stop-codon strain had spread to all individuals sampled. The presence of truncated E protein species within individual viral populations, along with a general relaxation in selective constraint, indicated that the stop-codon strain represents a defective lineage of DENV-1. We propose that such long-term transmission of defective RNA viruses in nature was achieved through complementation by coinfection of host cells with functional viruses.