Discovery of a novel iflavirus sequence in the eastern paralysis tick Ixodes holocyclus.

Ixodes holocyclus, the eastern paralysis tick, is a significant parasite in Australia in terms of animal and human health. However, very little is known about its virome. In this study, next-generation sequencing of I. holocyclus salivary glands yielded a full-length genome sequence which phylogenetically groups with viruses classified in the Iflaviridae family and shares 45% amino acid similarity with its closest relative Bole hyalomma asiaticum virus 1. The sequence of this virus, provisionally named Ixodes holocyclus iflavirus (IhIV) has been identified in tick populations from northern New South Wales and Queensland, Australia and represents the first virus sequence reported from I. holocyclus.

Integrative analysis of large scale transcriptome data draws a comprehensive landscape of Phaeodactylum tricornutum genome and evolutionary origin of diatoms.

Diatoms are one of the most successful and ecologically important groups of eukaryotic phytoplankton in the modern ocean. Deciphering their genomes is a key step towards better understanding of their biological innovations, evolutionary origins, and ecological underpinnings. Here, we have used 90 RNA-Seq datasets from different growth conditions combined with published expressed sequence tags and protein sequences from multiple taxa to explore the genome of the model diatom Phaeodactylum tricornutum, and introduce 1,489 novel genes. The new annotation additionally permitted the discovery of extensive alternative splicing in diatoms, including intron retention and exon skipping, which increase the diversity of transcripts generated in changing environments. In addition, we have used up-to-date reference sequence libraries to dissect the taxonomic origins of diatom genes. We show that the P. tricornutum genome is enriched in lineage-specific genes, with up to 47% of the gene models present only possessing orthologues in other stramenopile groups. Finally, we have performed a comprehensive de novo annotation of repetitive elements showing novel classes of transposable elements such as SINE, MITE and TRIM/LARD. This work provides a solid foundation for future studies of diatom gene function, evolution and ecology.

Recombinant LipL32 stimulates interferon-gamma production in cattle vaccinated with a monovalent Leptospira borgpetersenii serovar Hardjo subtype Hardjobovis vaccine.

Leptospira borgpetersenii serovar Hardjo subtype Hardjobovis (Hardjobovis) is the main causative agent of bovine leptospirosis in Australia, New Zealand, North America and elsewhere. Bovine leptospirosis can result in spontaneous abortion, stillbirth and reduced milk output. The organism is shed in the urine of infected animals and contact with contaminated materials can result in zoonotic infections in humans. Protective immunity in cattle against Hardjobovis involves stimulation of a Th1 cell mediated immune response, which can be characterized by the production of IFN-γ when blood from vaccinated animals is exposed to Hardjobovis antigens. However, the leptospiral components involved in stimulating this response have yet to be identified. In this study, 238 recombinant leptospiral proteins were evaluated for their ability to stimulate IFN-γ production in blood of cattle vaccinated with a commercial monovalent Hardjobovis vaccine. The conserved lipoprotein LipL32 is the major outer membrane protein of pathogenic Leptospira spp. A pool of soluble recombinant proteins which included LipL32, as well as LipL32 alone, stimulated significant IFN-γ production in blood of vaccinated cattle. A number of recombinant LipL32 fragments was generated, which identified the amino acids between 20 and 200 as containing the bovine T-cell reactive regions of LipL32. However, whether LipL32 plays a role in stimulating protective immunity in mammals has yet to be conclusively determined.

Evaluation of 238 antigens of Leptospira borgpetersenii serovar Hardjo for protection against kidney colonisation.

Leptospirosis is a zoonotic disease affecting animals and humans worldwide. Leptospiral infection in cattle can cause reproductive failure and reduced weight gain, and importantly, infection represents a significant disease risk for farmers. Current bacterin vaccines offer protection that is short-lived and restricted at best to related serovars. The development of protective vaccines that stimulate immunity across multiple leptospiral serovars would therefore be advantageous. This study used a reverse vaccinology approach to evaluate a set of Leptospira borgpetersenii proteins in the hamster infection model. The L. borgpetersenii serovar Hardjo strain L550 genome sequence was analysed and genes encoding 262 predicted outer membrane or secreted proteins were selected. From this list, 238 proteins or protein fragments were successfully expressed and purified; 28 proteins (12%) were soluble, while the remaining 210 proteins (88%) were insoluble and purified under denaturing conditions. Proteins were mixed into 48 pools of up to five each and tested for protection against infection as assessed by renal colonisation in the hamster model of infection. None of the pools of antigens protected the hamsters against infection, despite a detectable antibody response being mounted against the majority of proteins (71%). This study is the first large scale evaluation of individual leptospiral proteins for ability to induce a protective immune response in the hamster infection model. It thus constitutes an important reference of protein immunogenicity and non-protective antigens that should be consulted before embarking on any future subunit vaccine experiments.

Seroprevalence of Coxiella burnetii in Washington State domestic goat herds.

A caprine herd seroprevalence of Coxiella burnetii infection was determined by passive surveillance of domestic goat herds in Washington State. Serum samples (n=1794) from 105 herds in 31 counties were analyzed for C. burnetii antibodies using a commercially available Q fever antibody enzyme-linked immunosorbent assay (ELISA) test kit. The sera were submitted to the Washington Animal Disease Diagnostic Laboratory for routine serologic screening over an approximate 1-year period from November, 2010, through November, 2011. To avoid bias introduced by testing samples from ill animals, only accessions for routine screening of nonclinical animals were included in the study. A standard cluster sampling approach to investigate seroprevalence at the herd level was used to determine optimal study sample size. The results identified C. burnetii antibodies in 8.0% of samples tested (144/1794), 8.6% of goat herds tested (9/105), and 25.8% of counties tested (8/31). Within-herd seroprevalence in positive counties ranged from 2.9% to 75.8%. Counties with seropositive goats were represented in the western, eastern, southeastern, and Columbia basin agricultural districts of the state. To our knowledge this is the first county-specific, statewide study of C. burnetii seroprevalence in Washington State goat herds. The findings provide baseline information for future epidemiologic, herd management and public health investigations of Q fever.