Lyme disease ecology in San Luis Obispo County: The role of the western gray squirrel

Despite the fact that eight cases of Lyme disease were diagnosed in San Luis Obispo County between 2005-2013, the identity of wildlife hosts serving as sources for tick infection in this region remained unidentified. The primary cause of Lyme disease in the U.S. is the spirochetal bacterium Borrelia burgdorferi sensu stricto, and this agent had not been previously isolated from the region. Borrelia bissettii, a related species that has not been implicated as a common causative agent of Lyme disease, was isolated in small rodents inhabiting coastal scrub and chaparral habitats in a previous San Luis Obispo County study. However, B. burgdorferi was not detected. In northwestern California, B. burgdorferi has been primarily associated with high populations of the tick vector Ixodes pacificus in dense woodlands or hardwood-conifer habitats, particularly in the western gray squirrel reservoir host, Sciurus griseus. My study investigated the role of S. griseus and other associated rodents as potential reservoirs for B. burgdorferi in central coastal California woodland habitats. Rodents were live-trapped at four sites in San Luis Obispo County in oak and mixed woodland. Rodent ear samples were tested for B. burgdorferi genospecies by bacterial culture and PCR. Ticks were collected from captured rodents and surrounding environments and tested by PCR for the presence of Borrelia. Of 119 captured rodents, seven were positive for Borrelia infection (5.9%) and of these, six were positive for B. burgdorferi (5.0%). There were multiple infected rodent species that included two western gray squirrels, three deer mice (Peromyscus maniculatus), and one brush mouse (P. boylii). Borrelia spp. were not detected by PCR from the 81 ticks recovered from the environment and rodents. Here, for the first time, we verify the presence of B. burgdorferi sensu stricto in San Luis Obispo county rodents. However, in contrast to previous Northern California studies, the western gray squirrel may not be the primary reservoir host for B. burgdorferi in this region. Multiple rodent species in oak woodlands may be involved in spirochete maintenance in San Luis Obispo County

SPH Simulations of Negative (Nodal) Superhumps: A Parametric Study

Negative superhumps in cataclysmic variable systems result when the accretion disc is tilted with respect to the orbital plane. The line of nodes of the tilted disc precesses slowly in the retrograde direction, resulting in a photometric signal with a period slightly less than the orbital period. We use the method of smoothed particle hydrodynamics to simulate a series of models of differing mass ratio and effective viscosity to determine the retrograde precession period and superhump period deficit $\varepsilon_-$ as a function of system mass ratio $q$. We tabulate our results and present fits to both $\varepsilon_-$ and $\varepsilon_+$ versus $q$, as well as compare the numerical results with those compiled from the literature of negative superhump observations. One surprising is that while we find negative superhumps most clearly in simulations with an accretion stream present, we also find evidence for negative superhumps in simulations in which we shut off the mass transfer stream completely, indicating that the origin of the photometric signal is more complicated than previously believed.Comment: 14 pages, 15 figures. Accepted for publication in MNRA

Foot-and-Mouth Disease Virus Modulates Cellular Vimentin for Virus Survival

Foot-and-mouth disease virus (FMDV), the causative agent of foot-and-mouth disease, is an Aphthovirus within the Picornaviridae family. During infection with FMDV, several host cell membrane rearrangements occur to form sites of viral replication. FMDV protein 2C is part of the replication complex and thought to have multiple roles during virus replication. To better understand the role of 2C in the process of virus replication, we have been using a yeast two-hybrid approach to identify host proteins that interact with 2C. We recently reported that cellular Beclin1 is a natural ligand of 2C and that it is involved in the autophagy pathway, which was shown to be important for FMDV replication. Here, we report that cellular vimentin is also a specific host binding partner for 2C. The 2C-vimentin interaction was further confirmed by coimmunoprecipitation and immunofluorescence staining to occur in FMDV-infected cells. It was shown that upon infection a vimentin structure forms around 2C and that this structure is later resolved or disappears. Interestingly, overexpression of vimentin had no effect on virus replication; however, overexpression of a truncated dominant-negative form of vimentin resulted in a significant decrease in viral yield. Acrylamide, which causes disruption of vimentin filaments, also inhibited viral yield. Alanine scanning mutagenesis was used to map the specific amino acid residues in 2C critical for vimentin binding. Using reverse genetics, we identified 2C residues that are necessary for virus growth, suggesting that the interaction between FMDV 2C and cellular vimentin is essential for virus replication

Interaction of Structural Glycoprotein E2 of Classical Swine Fever Virus with Protein Phosphatase 1 Catalytic Subunit Beta (PPP1CB)

Classical swine fever virus (CSFV) E2 protein, the major virus structural glycoprotein, is an essential component of the viral envelope. E2 is involved in virus absorption, induction of a protective immune response and is critical for virulence in swine. Using the yeast two-hybrid system, we identified protein phosphatase 1 catalytic subunit beta (PPP1CB), which is part of the Protein Phosphatase 1 (PP1) complex, as a specific binding host partner for E2. We further confirmed the occurrence of this interaction in CSFV-infected swine cells by using two independent methodologies: Co-immunoprecipitation and Proximity Ligation Assay. In addition, we demonstrated that pharmacological activation of the PP1 pathway has a negative effect on CSFV replication while inhibition of the PP1 pathway or knockdown of PPP1CB by siRNA had no observed effect. Overall, our data suggests that the CSFV E2 and PPP1CB protein interact in infected cells, and that activation of the PP1 pathway decreases virus replication