Analysis of a pair of END+ and END? viruses derived from the same bovine viral diarrhea virus stock reveals the amino acid determinants in Npro responsible for inhibition of type I interferon production

The Exaltation of Newcastle disease virus (END) phenomenon is induced by the inhibition of type I interferon in pestivirus-infected cells in vitro, via proteasomal degradation of cellular interferon regulatory factor (IRF)-3 with the property of the viral autoprotease protein N^pro. Reportedly, the amino acid residues in the zinc-binding TRASH motif of N^pro determine the difference in characteristics between END-phenomenon-positive (END⁺) and END-phenomenon-negative (END⁻) classical swine fever viruses (CSFVs). However, the basic mechanism underlying this function in bovine viral diarrhea virus (BVDV) has not been elucidated from the genomic differences between END⁺ and END⁻ viruses using reverse genetics till date. In the present study, comparison of complete genome sequences of a pair of END⁺ and END⁻ viruses isolated from the same virus stock revealed that there were only four amino acid substitutions (D136G, I2623V, D3148G and D3502Y) between two viruses. Based on these differences, viruses with and without mutations at these positions were generated using reverse genetics. The END assay, measurements of induced type I interferon and IRF-3 detection in cells infected with these viruses revealed that the aspartic acid at position 136 in the zinc-binding TRASH motif of N^pro was required to inhibit the production of type I interferon via the degradation of cellular IRF-3, consistently with CSFV.     

A low pathogenic H5N2 influenza virus isolated in Taiwan acquired high pathogenicity by consecutive passages in chickens

H5N2 viruses were isolated from cloacal swab samples of apparently healthy chickens in Taiwan in 2003 and 2008 during surveillance of avian influenza. Each of the viruses was eradicated by stamping out. The official diagnosis report indicated that the Intravenous Pathogenicity Indexes (IVPIs) of the isolates were 0.00 and 0.89, respectively, indicating that these were low pathogenic strains, although the hemagglutinin of the strain isolated in 2008 (Taiwan08) had multibasic amino acid residues at the cleavage site (PQRKKR/G). In the present study, these H5N2 viruses were assessed for their intravenous and intranasal pathogenicity for chickens. It was examined whether Taiwan08 acquires pathogenicity through consecutive passages in chickens. Intravenous pathogenicity of Taiwan08 depended upon the age of the chickens used for the IVPI test; all of the eight-week-old chickens intravenously inoculated with Taiwan08 showed clinical signs but survived for ten days post inoculation (IVPI=0.68), whereas all the six-week-old chickens died (IVPI=1.86). Taiwan08-P8, which were passaged in chickens for eight times, killed all the eight-week-old chickens (IVPI=2.36). The four-week-old chickens died after intranasal inoculation of Taiwan08-P8, indicating that Taiwan08 must have become highly pathogenic during circulation in chicken flocks. These results emphasize the importance of a stamping out policy for avian influenza even if the IVPI of the causal virus is low.     

Risk profile of low pathogenicity avian influenza virus infections in farms in southern Vietnam

The impact of low pathogenicity avian influenza (LPAI) has been confirmed mainly in farms. Unlike apparent losses caused by the high pathogenicity avian influenza (HPAI), the LPAI impact has been hardly evaluated due to underestimating its spread and damage. In 2019, a questionnaire study was conducted in southern Vietnam to identify the specific risk factors of LPAI virus (LPAIV) circulation and to find associations between husbandry activities and LPAI prevalence. A multilevel regression analysis indicated that keeping Muscovy ducks during farming contributed to LPAIV positivity [Odds ratio=208.2 (95% confidence interval: 13.4–1.1 × 10⁴)]. In cluster analysis, farmers willing to report avian influenza (AI) events and who agreed with the local AI control policy had a slightly lower risk for LPAIV infection although there was no significance in the correlation between farmer characteristics and LPAI occurrence. These findings indicated that keeping Muscovy ducks without appropriate countermeasures might increase the risk of LPAIV infection. Furthermore, specific control measures at the local level are effective for LPAIV circulation, and the improvement of knowledge about biosecurity and attitude contributes to reducing LPAI damage.     

Postnatal testicular development and actin appearance in the seminiferous epithelium of the Habu,Trimeresurus flavoviridis

The postnatal testicular development and actin distribution in the seminiferous epithelium were examined by light microscopy, using the testes of the Habu (Trimeresurus flavoviridis; snake) from 0-year-old to 3-year-old. At 0-year-old (about 1 month after birth), the testis was quite small in size, and the seminiferous epithelium was composed of only Sertoli cells and large spermatogonia. Actin immunoreactivity was observed in the peritubular myoid cells, but could not be detected in the seminiferous epithelium. At 1-year-old (about 10 months after birth), the testicular size increased to a great degree. In the seminiferous epithelium, spermatocytes newly appeared. Actin could still not be detected in the seminiferous epithelium. At 2-year-old (about 1 year and 10 months after birth), the testes continued to develop in size. In the seminiferous epithelium, elongate spermatids and round spermatids were frequently seen, in addition to Sertoli cells, spermatogonia and spermatocytes. Thus, active spermatogenesis was clearly recognized at this age. Moreover, the actin distribution in the seminiferous epithelium was observed at the site between Sertoli cells and spermatids, as well as that at adult stage. The immunoreactivity of actin in the peritubular myoid cells gradually increased from 0-year-old to 2-year-old. Conclusively, it seems likely that spermatogenesis in the Habu initiates at 2-year-old, accompanying with the appearance of actin in the seminiferous epithelium.     

Age estimation by DNA methylation in the Antarctic minke whale

Fisheries Science - Determining the age of wild animals is very important in the study of their ecology and for stock assessment and management. In baleen whales, the most common approach for age...     

Engineered interface of magnetic oxides

Interface-selective probing of magnetism is a key issue for the design and realization of spin-electronic junction devices. Here, magnetization-induced second-harmonic generation was used to probe the local magnetic properties at the interface of the perovskite ferromagnet La(0.6)Sr(0.4)MnO3 with nonmagnetic insulating layers, as used in spin-tunnel junctions. We show that by grading the doping profile on an atomic scale at the interface, robust ferromagnetism can be realized around room temperature. The results should lead to improvements in the performance of spin-tunnel junctions.     

Toluene Exposure Leads to a Change in Expression Patterns of β Defensins in the Mouse Tracheal Epithelium

Defensins are generally implicated in the quick resistance of epithelial surfaces to microbials; however, recent reports have indicated that defensins also have unknown purposes in relation to noninfectious diseases. In this study, the localization patterns of anti-microbial peptides, β defensins (BDs), in the tracheal epithelium of male C3H mice under exposure to toluene were analyzed by immunohistochemistry. Mice were exposed one to ten times to toluene for 30 min by nose-only inhalation. Expression of BDs was revealed by immunohistochemistry in serial sections of trachea after the final exposure. Expression of BD-1 was usually observed at almost the same levels in all exposure groups, and expression of BD-2 was observed in the control group; however, the signals for BD-2 decreased gradually with frequency of exposure. In the group exposed ten times, expression of BD-2 decreased to far lower than that of the control group. No expression of BD-3 was detected in any groups. Interestingly, expression of BD-4 increased to the maximum in the group exposed four times and decreased to a level lower than that of the control in the group exposed ten times. The results of the present study indicated that toluene gas might change the expression pattern of BDs in the tracheal epithelial cells. The oscillation of expression of BD-4 was quite characteristic and might contribute to morphological damage in on the epithelial cells.     

Dependence of dispersion on vegetation density in a tidal creek‐mangrove swamp system

The dependence of dispersion in a tidal creek on the vegetation density in a fringing mangrove swamp is discussed through a numerical model. A secondary circulation prevails everywhere in the tidal creekmangrove swamp system and is generated by the overflow into the swamp at every high tide. As a result, dissolved and suspended matter moving with the circulation is trapped in the swamp for a fraction of the tidal cycle; it flows out of the swamp at ebb tide and disperses in the creek. The relation between the dispersion coefficient and the mangrove vegetation density is shown to be nonlinear. Dispersion is large both for bare and high vegetation densities and minimum for intermediate vegetation density. The ecological and management applications may be profound as our study suggests that such systems may be unstable and cannot naturally recover from excessive anthropogenic disturbances.     

Molecular Phylogenetic Analysis of Ribosomal DNA Internal Transcribed Spacer Regions and Comparison of Fertility in <Emphasis Type="Italic">Phomopsis </Emphasis>Isolates from Fruit Trees

Sequences of the ribosomal DNA (rDNA) internal transcribed spacer (ITS) regions were examined to infer a molecular phylogeny of small-spored Phomopsis isolates, designated W-type (mainly white colony, weakly virulent, bearing both alpha and beta conidia at 25°C on PDA) and G-type (mainly gray colony, highly virulent, bearing only alpha conidia at 25°C on PDA), and P. amygdali from fruit trees. Phomopsis G-type and P. amygdali were a monophyletic group distinct from the W-type. The W-type isolates were divided into two monophyletic groups. Diaporthe citri, D. tanakae, P. asparagi, P. viticola, P. vitimegaspora and D. nomurai, which are morphologically distinguishable from W- and G-types, differed from the W- and G-types in molecular phylogenetic analyses. PCR-RFLP analysis of rDNA ITS regions was useful to distinguish each of the Phomopsis species and groups using three restriction enzymes. In mating tests, W-type isolates from fruit trees were heterothallic and inter-fertile even between isolates belonging to the different monophyletic groups. Isolates of the G-type and P. amygdali collected in Japan were cross-fertile. Some isolates from Lunaria annua, Ulmus glabra and Juglans regia belonged to one of the two monophyletic groups of the W-type and were cross-fertile with W-type isolates from Rosaceous fruit trees. Received 27 September 1999/ Accepted in revised form 27 January 2000