Insulin Stimulates the Phosphorylation of the Exocyst Protein Sec8 in Adipocytes

The signal transduction pathway leading from the insulin receptor to stimulate the fusion of vesicles containing the glucose transporter GLUT4 with the plasma membrane in adipocytes and muscle cells is not completely understood. Current evidence suggests that in addition to the Rab GTPase-activating protein AS160, at least one other substrate of Akt (also called protein kinase B), which is as yet unidentified, is required. Sec8 is a component of the exocyst complex that has been previously implicated in GLUT4 trafficking. In the present study, we report that insulin stimulates the phosphorylation of Sec8 on Ser-32 in 3T3-L1 adipocytes. On the basis of the sequence around Ser-32 and the finding that phosphorylation is inhibited by the PI3K (phosphoinositide 3-kinase) inhibitor wortmannin, it is likely that Akt is the kinase for Ser-32. We examined the possible role of Ser-32 phosphorylation in the insulin-stimulated trafficking of GLUT4, as well as the TfR (transferrin receptor), to the plasma membrane by determining the effects of overexpression of the non-phosphorylatable S32A mutant of Sec8 and the phosphomimetic S32E mutant of Sec8. Substantial overexpression of both mutants had no effect on the amount of GLUT4 or TfR at the cell surface in either the untreated or insulin-treated states. These results indicate that insulin-stimulated phosphorylation of Sec8 is not part of the mechanism by which insulin enhances the fusion of vesicles with the plasma membrane

Serological evidence of a pararubulavirus and a betacoronavirus in the geographically isolated Christmas Island flying-fox (Pteropus natalis)

Due to their geographical isolation and small populations, insular bats may not be able to maintain acute immunizing viruses that rely on a large population for viral maintenance. Instead, endemic transmission may rely on viruses establishing persistent infections within hosts or inducing only short-lived neutralizing immunity. Therefore, studies on insular populations are valuable for developing broader understanding of viral maintenance in bats. The Christmas Island flying-fox (CIFF; Pteropus natalis) is endemic on Christmas Island, a remote Australian territory, and is an ideal model species to understand viral maintenance in small, geographically isolated bat populations. Serum or plasma (n = 190), oral swabs (n = 199), faeces (n = 31), urine (n = 32) and urine swabs (n = 25) were collected from 228 CIFFs. Samples were tested using multiplex serological and molecular assays, and attempts at virus isolation to determine the presence of paramyxoviruses, betacoronaviruses and Australian bat lyssavirus. Analysis of serological data provides evidence that the species is maintaining a pararubulavirus and a betacoronavirus. There was little serological evidence supporting the presence of active circulation of the other viruses assessed in the present study. No viral nucleic acid was detected and no viruses were isolated. Age-seropositivity results support the hypothesis that geographically isolated bat populations can maintain some paramyxoviruses and coronaviruses. Further studies are required to elucidate infection dynamics and characterize viruses in the CIFF. Lastly, apparent absence of some pathogens could have implications for the conservation of the CIFF if a novel disease were introduced into the population through human carriage or an invasive species. Adopting increased biosecurity protocols for ships porting on Christmas Island and for researchers and bat carers working with flying-foxes are recommended to decrease the risk of pathogen introduction and contribute to the health and conservation of the species

Pan-serotype diagnostic for foot-and-mouth disease using the consensus antigen of nonstructural protein 3B

An amino acid consensus sequence for the seven serotypes of foot-and-mouth disease virus (FMDV) nonstructural protein 3B, including all three contiguous repeats, and its use in the development of a pan-serotype diagnostic test for all seven FMDV serotypes are described. The amino acid consensus sequence of the 3B protein was determined from a multiple-sequence alignment of 125 sequences of 3B. The consensus 3B (c3B) protein was expressed as a soluble recombinant fusion protein with maltose-binding protein (MBP) using a bacterial expression system and was affinity purified using amylose resin. The MBP-c3B protein was used as the antigen in the development of a competition enzyme-linked immunosorbent assay (cELISA) for detection of anti-3B antibodies in bovine sera. The comparative diagnostic sensitivity and specificity at 47% inhibition were estimated to be 87.22% and 93.15%, respectively. Reactivity of c3B with bovine sera representing the seven FMDV serotypes demonstrated the pan-serotype diagnostic capability of this bioreagent. The consensus antigen and competition ELISA are described here as candidates for a pan-serotype diagnostic test for FMDV infection

Seroprevalence of three paramyxoviruses; Hendra virus, Tioman virus, Cedar virus and a rhabdovirus, Australian bat lyssavirus, in a range expanding fruit bat, the Grey-headed flying fox (Pteropus poliocephalus).

Habitat-mediated global change is driving shifts in species' distributions which can alter the spatial risks associated with emerging zoonotic pathogens. Many emerging infectious pathogens are transmitted by highly mobile species, including bats, which can act as spill-over hosts for pathogenic viruses. Over three years, we investigated the seroepidemiology of paramyxoviruses and Australian bat lyssavirus in a range-expanding fruit bat, the Grey-headed flying fox (Pteropus poliocephalus), in a new camp in Adelaide, South Australia. Over six, biannual, sampling sessions, we quantified median florescent intensity (MFI) antibody levels for four viruses for a total of 297 individual bats using a multiplex Luminex binding assay. Where appropriate, florescence thresholds were determined using finite mixture modelling to classify bats' serological status. Overall, apparent seroprevalence of antibodies directed at Hendra, Cedar and Tioman virus antigens was 43.2%, 26.6% and 95.7%, respectively. We used hurdle models to explore correlates of seropositivity and antibody levels when seropositive. Increased body condition was significantly associated with Hendra seropositivity (Odds ratio = 3.67; p = 0.002) and Hendra virus levels were significantly higher in pregnant females (p = 0.002). While most bats were seropositive for Tioman virus, antibody levels for this virus were significantly higher in adults (p < 0.001). Unexpectedly, all sera were negative for Australian bat lyssavirus. Temporal variation in antibody levels suggests that antibodies to Hendra virus and Tioman virus may wax and wane on a seasonal basis. These findings suggest a common exposure to Hendra virus and other paramyxoviruses in this flying fox camp in South Australia

Hayes Yard virus: a novel ephemerovirus isolated from a bull with severe clinical signs of bovine ephemeral fever is most closely related to Puchong virus

Bovine ephemeral fever is a vector-borne disease of ruminants that occurs in tropical and sub-tropical regions of Africa, Asia and Australia. The disease is caused by a rhabdovirus, bovine ephemeral fever virus (BEFV), which occurs as a single serotype globally. Although several other closely related ephemeroviruses have been isolated from cattle and/or arthropods, only kotonkan virus from Nigeria and (tentatively) Mavingoni virus from Mayotte Island in the Indian Ocean have been previously associated with febrile disease. Here, we report the isolation of a novel virus (Hayes Yard virus; HYV) from blood collected in February 2000 from a bull (Bos indicus) in the Northern Territory of Australia. The animal was suffering from a severe ephemeral fever-like illness with neurological involvement, including recumbency and paralysis, and was euthanised. Histological examination of spinal cord and lung tissue identified extensive haemorrhage in the dura mata with moderate perineuronal oedema and extensive emphysema. HYV displayed cone-shaped morphology, typical of rhabdoviruses, and was found to be most closely related antigenically to Puchong virus (PUCV), isolated in 1965 from mosquitoes in Malaysia. Analysis of complete genome sequences of HYV (15 025 nt) and PUCV (14 932 nt) indicated that each has a complex organisation (3 ' N-P-M-G-G(NS)-alpha 1-alpha 2-beta-gamma-L 5 ') and expression strategy, similar to that of BEFV. Based on an alignment of complete L protein sequences, HYV and PUCV cluster with other rhabdoviruses in the genus Ephemerovirus and appear to represent two new species. Neutralising antibody to HYV was also detected in a retrospective survey of cattle sera collected in the Northern Territory

Purification and Characterisation of Immunoglobulins from the Australian Black Flying Fox (<em>Pteropus alecto</em>) Using Anti-Fab Affinity Chromatography Reveals the Low Abundance of IgA

<div><p>There is now an overwhelming body of evidence that implicates bats in the dissemination of a long list of emerging and re-emerging viral agents, often causing illnesses or death in both animals and humans. Despite this, there is a paucity of information regarding the immunological mechanisms by which bats coexist with highly pathogenic viruses. Immunoglobulins are major components of the adaptive immune system. Early studies found bats may have quantitatively lower antibody responses to model antigens compared to conventional laboratory animals. To further understand the antibody response of bats, the present study purified and characterised the major immunoglobulin classes from healthy black flying foxes, <em>Pteropus alecto</em>. We employed a novel strategy, where IgG was initially purified and used to generate anti-Fab specific antibodies. Immobilised anti-Fab specific antibodies were then used to capture other immunoglobulins from IgG depleted serum. While high quantities of IgM were successfully isolated from serum, IgA was not. Only trace quantities of IgA were detected in the serum by mass spectrometry. Immobilised ligands specific to IgA (Jacalin, Peptide M and staphylococcal superantigen-like protein) also failed to capture <em>P. alecto</em> IgA from serum. IgM was the second most abundant serum antibody after IgG. A survey of mucosal secretions found IgG was the dominant antibody class rather than IgA. Our study demonstrates healthy <em>P. alecto</em> bats have markedly less serum IgA than expected. Higher quantities of IgG in mucosal secretions may be compensation for this low abundance or lack of IgA. Knowledge and reagents developed within this study can be used in the future to examine class-specific antibody response within this important viral host.</p> </div

Quantitative measurement of <i>IGHG</i>, <i>IGHM</i>, <i>IGHA</i>, <i>IGJ</i> and <i>PIGR</i> mRNA in <i>P. alecto</i> tissues.

<p>mRNA transcripts were measured by SYBR Green qPCR and normalised to 18 s ribosomal RNA. Results show the mean ± standard deviation of n = 3 individual healthy wild-caught bats. Abbreviations: L.N., lymph node; S.I., small intestine; S.G., salivary gland; PBMC, peripheral blood mononuclear cells.</p