Highly Pathogenic H5N1 Influenza Virus Infection in Migratory Birds

H5N1avianinfluenza virus(AIV)has emerged as a pathogenic entityfor a variety of species,including humans,inre-cent years.Here we report an outbreak among migratory birds on Lake Qinghaihu,China,in May and June2005,inwhich more than a thousand birds were affected.Pancreatic necrosis and abnormal neurological symptoms were the majorclinical features.Sequencing of the complete genomes of four H5N1AIVstrains revealedthemto be reassortants relatedto a peregrine falconisolate from Hong Kong an…     

Characterization of low-pathogenicity H5N1 avian influenza viruses from North America

Wild-bird surveillance in North America for avian influenza (AI) viruses with a goal of early identification of the Asian H5N1 highly pathogenic AI virus has identified at least six low-pathogenicity H5N1 AI viruses between 2004 and 2006. The hemagglutinin (HA) and neuraminidase (NA) genes from all 6 H5N1 viruses and an additional 38 North American wild-bird-origin H5 subtype and 28 N1 subtype viruses were sequenced and compared with sequences available in GenBank by phylogenetic analysis. Both HA and NA were phylogenetically distinct from those for viruses from outside of North America and from those for viruses recovered from mammals. Four of the H5N1 AI viruses were characterized as low pathogenicity by standard in vivo pathotyping tests. One of the H5N1 viruses, A/MuteSwan/MI/451072-2/06, was shown to replicate to low titers in chickens, turkeys, and ducks. However, transmission of A/MuteSwan/MI/451072-2/06 was more efficient among ducks than among chickens or turkeys based on virus shed. The 50% chicken infectious dose for A/MuteSwan/MI/451072-2/06 and three other wild-waterfowl-origin H5 viruses were also determined and were between 10(5.3) and 10(7.5) 50% egg infective doses. Finally, seven H5 viruses representing different phylogenetic clades were evaluated for their antigenic relatedness by hemagglutination inhibition assay, showing that the antigenic relatedness was largely associated with geographic origin. Overall, the data support the conclusion that North American H5 wild-bird-origin AI viruses are low-pathogenicity wild-bird-adapted viruses and are antigenically and genetically distinct from the highly pathogenic Asian H5N1 virus lineage.     

Potential palaeoflora of Last Glacial Maximum Eastern Beringia,northwest North America

Vegetation History and Archaeobotany - Potential Last Glacial Maximum (LGM, 26,500–15,000 bp) members of the Eastern Beringia (now Alaska-Yukon, northwest North America) vascular...     

A Method for Investigating Population Declines of Migratory Birds Using Stable Isotopes: Origins of Harvested Lesser Scaup in North America

Background

Elucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging.

Methodology/Findings

Here we used hydrogen isotopes (δD) to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis) harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999–2000 (n = 412) and 2000–2001 (n = 455). We combined geospatial, observational, and analytical data sources, including known scaup breeding range, δD values of feathers from juveniles at natal sites, models of δD for growing-season precipitation, and scaup band-recovery data to generate probabilistic natal origin landscapes for individual scaup. We then used Monte Carlo integration to model assignment uncertainty from among individual δD variance estimates from birds of known molt origin and also from band-return data summarized at the flyway level. We compared the distribution of scaup natal origin with the distribution of breeding population counts obtained from systematic long-term surveys.

Conclusions/Significance

Our analysis revealed that the proportion of young scaup produced in the northern (above 60°N) versus the southern boreal and Prairie-Parkland region was inversely related to the proportions of breeding adults using these regions, suggesting that despite having a higher relative abundance of breeding adults, the northern boreal region was less productive for scaup recruitment into the harvest than more southern biomes. Our approach for evaluating population declines of migratory birds (particularly game birds) synthesizes all available distributional data and exploits the advantages of intrinsic isotopic markers that link individuals to geography.     

Highly pathogenic H5N1 avian influenza: entry pathways into North America via bird migration

Given the possibility of highly pathogenic H5N1 avian influenza arriving in North America and monitoring programs that have been established to detect and track it, we review intercontinental movements of birds. We divided 157 bird species showing regular intercontinental movements into four groups based on patterns of movement-one of these groups (breed Holarctic, winter Eurasia) fits well with the design of the monitoring programs (i.e., western Alaska), but the other groups have quite different movement patterns, which would suggest the importance of H5N1 monitoring along the Pacific, Atlantic, and Gulf coasts of North America.     

Intercontinental genetic divergence of Castanea species in eastern Asia and eastern North America

Castanea is one of the many plant genera with a disjunct distribution pattern between eastern Asia and eastern North America. Five species from three sections of the genus were investigated to examine genetic divergence between eastern Asian and eastern North American species. A total of 62 native populations were sampled for allelic variation at isozyme loci. The Chinese chestnut C. mollissima had the highest genetic variability, while the American C. dentata had the lowest genetic variability. The highest intracontinental genetic identities were observed between the Allegheny and Ozark chinkapins (0.931) and between C. mollissima and C. seguinii (0.870), while lower identities were detected between the American C. pumila and C. dentata (0.720-0.729). In intercontinental comparisons, genetic identities of 0.505, 0.495 and 0.507 were observed between the American chestnut and the Chinese C. mollissima, C. seguinii and C. henryi, respectively, whereas the Ozark chinkapin C. pumila var. ozarkensis had lower identities of 0.469, and 0.435 with C. mollissima and C. seguinii, respectively, but a slightly higher identity of 0.520 with C. henryi, the Chinese chinkapin. Divergence times were estimated at 10-13 million years before present between C. dentata and C. mollissima, and C. pumila var. ozarkensis and C. henryi.     

The Cold European Winter of 2005–2006 Assisted the Spread and Persistence of H5N1 Influenza Virus in Wild Birds

In January 2006, a major cold spell affected Europe, coinciding with an increase of H5N1 influenza virus detected in wild birds, mostly dead mute swans, starting along the River Danube and the Mediterranean coast line. Subsequently H5N1 detections in wild birds were concentrated in central and western parts of Europe, reaching a peak in mid February. We tested the hypothesis that the geographic distribution of these H5N1 infections was modulated by the long-term wintering line, the 0°C isotherm marking the limit beyond which areas are largely unsuitable for wintering waterfowl. Given the particularly cold 2005–2006 European winter, we also considered the satellite-derived contemporary frost conditions. This brought us to select the long-term maximum rather than the mean January 0°C isotherm as the best approximation for the 2005–2006 wintering line. Our analysis shows that H5N1 detection sites were closer to the wintering line than would be expected by chance, even when the geographic distribution of water bird wintering sites was accounted for. We argue that partial frost conditions in water bodies are conducive to bird congregation, and this may have enhanced H5N1 transmission and local spread. Because the environmental virus load also would build up in these hot spots, H5N1 virus may have readily persisted during the spring, at least in cooler areas. We conclude that H5N1 introduction, spread, and persistence in Europe may have been enhanced by the cold 2005–2006 winter.     

Natural Spread of Plant Viruses by Birds

Observations made in Mali strongly suggest that Rice yellow mottle virus (RYMV) is spread by weaverbirds (Quelea quelea) below and around baobab trees (Adansonia digitata) in which they nest. Rice leaves in bird nests appeared to be infected. In Spain, an infection of Southern bean mosaic virus (SBMV) in string (climbing) beans (Phaseolus vulgaris) was apparently introduced and spread by sparrows (Passer domesticus) judging from the damage caused on flowers and bean pods. Damaged leaves and pods on SBMV‐infected plants were also found in a screenhouse visited by sparrows and bulbuls (Pycnonotus barbatus) in Morocco. These observations showed that both viruses could be spread by birds when either collecting infected leaves for nesting or feeding on infected plants.     

Migratory Status Is Not Related to the Susceptibility to HPAIV H5N1 in an Insectivorous Passerine Species

Migratory birds have evolved elaborate physiological adaptations to travelling, the implications for their susceptibility to avian influenza are however unknown. Three groups of stonechats (Saxicola torquata) from (I) strongly migrating, (II) weakly migrating and (III) non-migrating populations were experimentally infected with HPAIV H5N1. The different bird groups of this insectivorous passerine species were infected in autumn, when the migrating populations clearly exhibit migratory restlessness. Following infection, all animals succumbed to the disease from 3 through 7 days post inoculation. Viral shedding, antigen distribution in tissues, and survival time did not differ between the three populations. However, notably, endothelial tropism of the HPAIV infection was exclusively seen in the group of resident birds. In conclusion, our data document for the first time the high susceptibility of an insectivorous passerine species to H5N1 infection, and the epidemiological role of these passerine birds is probably limited due to their high sensitivity to HPAIV H5N1 infection. Despite pronounced inherited differences in migratory status, the groups were generally indistinguishable in their susceptibility, survival time, clinical symptoms and viral shedding. Nevertheless, the migratory status partly influenced pathogenesis in the way of viral tropism.     

Spread of H5N1 avian influenza virus: an ecological conundrum

The role of wild birds in the spread of influenza H5N1 virus remains speculative and the ecology of influenza A viruses in nature is largely unstudied. There is an urgent need for multidisciplinary studies to explore the ecology of avian influenza viruses in wild birds and the environment to support ecological interpretation of the source of disease outbreaks in poultry.     

宠物鸟H3N8亚型流行性感冒病毒NA基因分子特征性分析

虽然流行性感冒(流感)病毒的自然宿主是野生水禽类,作为宠物的雀形目鸟(Passeriformes)不代表流感病毒主要储存库,但Stallknecht和Shane 1988年对21318份鸟的样品分析后发现,雀形目鸟中流感病毒的分离率占2．9％,表明雀形目鸟在流感病毒储存库中起着一定的作用。另外,这类鸟种类繁多,分布于世界各地,国际贸易又加强了这类鸟在世界范围的流动性,     

Serological Evidence for Non-Lethal Exposures of Mongolian Wild Birds to Highly Pathogenic Avian Influenza H5N1 Virus

Surveillance for highly pathogenic avian influenza viruses (HPAIV) in wild birds is logistically demanding due to the very low rates of virus detection. Serological approaches may be more cost effective as they require smaller sample sizes to identify exposed populations. We hypothesized that antigenic differences between classical Eurasian H5 subtype viruses (which have low pathogenicity in chickens) and H5N1 viruses of the Goose/Guangdong/96 H5 lineage (which are HPAIV) may be used to differentiate populations where HPAIVs have been circulating, from those where they have not. To test this we performed hemagglutination inhibition assays to compare the reactivity of serum samples from wild birds in Mongolia (where HPAIV has been circulating, n = 1,832) and Europe (where HPAIV has been rare or absent, n = 497) to a panel of reference viruses including classical Eurasian H5 (of low pathogenicity), and five HPAIV H5N1 antigens of the Asian lineage A/Goose/Guangdong/1/96. Antibody titres were detected against at least one of the test antigens for 182 Mongolian serum samples (total seroprevalence of 0.10, n = 1,832, 95% adjusted Wald confidence limits of 0.09–0.11) and 25 of the European sera tested (total seroprevalence of 0.05, n = 497, 95% adjusted Wald confidence limits of 0.03–0.07). A bias in antibody titres to HPAIV antigens was found in the Mongolian sample set (22/182) that was absent in the European sera (0/25). Although the interpretation of serological data from wild birds is complicated by the possibility of exposure to multiple strains, and variability in the timing of exposure, these findings suggest that a proportion of the Mongolian population had survived exposure to HPAIV, and that serological assays may enhance the targeting of traditional HPAIV surveillance toward populations where isolation of HPAIV is more likely.     

Prediction of Mutations Initiated by Internal Power in H3N2 Hemagglutinins of Influenza A Virus from North America

Probably the best way to predict mutations is to find the cause for mutations, by which the cause–mutation relationship can be built. However, many causes which have resulted in mutations in the past might not leave any trace due to the changes in environments. As well, the current proteins may not be sensitive to the causes, which led to mutations in the past, because of evolution. Thus we might have recorded many mutations, but few of their corresponding causes, and it would be difficult to establish the one-to-one cause–mutation relationship. However, the internal power engineering mutations within a protein would exist, of which randomness should play an important role. Since 1999, we have developed three methods to quantify the randomness within a protein by which we can build a cause–mutation relationship because we can classify the occurrence and non-occurrence of mutation as unity and zero, and transfer this relationship into the classification problem, which can be solved using logistic regression. Recently, we used the logistic regression to predict the mutation positions in H5N1 hemagglutinins from influenza A virus, and applied the amino-acid mutating probability to predict the would-be-mutated amino acids at predicted positions as the concept-initiated study. However, we still need to conduct many proof-of-concept studies to test whether this cause–mutation relationship is independent of protein subtypes, whether the logistic regression is powerful enough, etc. In this study, we attempted to use the logistic regression to predict the mutation positions in H3N2 hemagglutinins of influenza A virus from North America to answer the questions in the proof-of-concept stage.