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Evolution of bluetongue virus serotype 1 in northern Australia over 30 years.

ABSTRACT: Bluetongue virus serotype 1 (BTV 1) was first isolated in Australia from cattle blood collected in 1979 at Beatrice Hill Farm (BHF), Northern Territory (NT). From long-term surveillance programs (1977 to 2011), 2,487 isolations of 10 BTV serotypes were made. The most frequently isolated serotype was BTV 1 (41%, 1,019) followed by BTV 16 (17.5%, 436) and BTV 20 (14%, 348). In 3 years, no BTVs were isolated, and in 12 years, no BTV 1 was isolated. Seventeen BTV 1 isolates were sequenced and analyzed in comparison with 10 Australian prototype serotypes. BTV 1 showed an episodic pattern of evolutionary change characterized by four distinct periods. Each period consisted primarily of slow genetic drift which was punctuated from time to time by genetic shifts generated by segment reassortment and the introduction of new genome segments. Evidence was found for coevolution of BTV genome segments. Evolutionary dynamics and selection pressure estimates showed strong temporal and clock-like molecular evolutionary dynamics of six Australian BTV genome segments. Bayesian coalescent estimates of mean substitution rates clustered in the range of 3.5 × 10(-4) to 5.3 × 10(-4) substitutions per site per year. All BTV genome segments evolved under strong purifying (negative) selection, with only three sites identified as under pervasive diversifying (positive) selection. The obligate replication in alternate hosts (insect vector and vertebrate hosts) imposed strong evolutionary constraints. The dominant mechanism generating genetic diversity of BTV 1 at BHF was through the introduction of new viruses and reassortment of genome segments with existing viruses.Bluetongue virus (BTV) is the causative agent of bluetongue disease in ruminants. It is a disease of concern globally and is transmitted by biting midges (Culicoides species). Analysis of the evolutionary and selection pressures on BTV 1 at a single surveillance site in northern Australia showed strong temporal and clock-like dynamics. Obligate replication in alternate hosts of insect and vertebrate imposed strong evolutionary constraints, with all BTV genome segments evolving under strong purifying (negative) selection. Generation of genetic diversity of BTV 1 in northern Australia is through genome segment reassortment and the introduction of new serotypes.

SUBMITTER: Boyle DB

PROVIDER: S-EPMC4249141 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Evolution of bluetongue virus serotype 1 in northern Australia over 30 years.

Boyle David B DB Amos-Ritchie Rachel R Broz Ivano I Walker Peter J PJ Melville Lorna L Flanagan David D Davis Steven S Hunt Neville N Weir Richard R

Journal of virology 20140924 24

<h4>Unlabelled</h4>Bluetongue virus serotype 1 (BTV 1) was first isolated in Australia from cattle blood collected in 1979 at Beatrice Hill Farm (BHF), Northern Territory (NT). From long-term surveillance programs (1977 to 2011), 2,487 isolations of 10 BTV serotypes were made. The most frequently isolated serotype was BTV 1 (41%, 1,019) followed by BTV 16 (17.5%, 436) and BTV 20 (14%, 348). In 3 years, no BTVs were isolated, and in 12 years, no BTV 1 was isolated. Seventeen BTV 1 isolates were s ...[more]

PMID: 25253345

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Project description:Bluetongue virus (BTV), transmitted by midges (Culicoides sp), is distributed worldwide and causes disease in ruminants. In particular, BT can be a debilitating disease in sheep causing serious trade and socio-economic consequences at both local and global levels. Across Australia, a sentinel cattle herd surveillance program monitors the BTV activity. Prior to 2014, BTV-1, -2, -3, -7, -9, -15, -16, -20, -21 and -23 had been isolated in Australia, but no bluetongue disease has occurred in a commercial Australian flock. We routinely use a combination of serology, virus isolation, RT-PCR and next generation and conventional nucleotide sequencing technologies to detect and phylogenetically characterize incursions of novel BTV strains into Australia. Screening of Northern Territory virus isolates in 2015 revealed BTV-5, a serotype new to Australia. We derived the complete genome of this isolate and determined its phylogenetic relationship with exotic BTV-5 isolates. Gene segments 2, 6, 7 and 10 exhibited a close relationship with the South African prototype isolate RSArrrr/5. This was the first Australian isolation of a Western topotype of segment 10. Serological surveillance data highlighted the antigenic cross-reactivity between BTV-5 and BTV-9. Phylogenetic investigation of segments 2 and 6 of these serotypes confirmed their unconventional relationships within the BTV serogroup. Our results further highlighted a need for a revision of the current serologically based system for BTV strain differentiation and importantly, implied a potential for genome segments of pathogenic Western BTV strains to rapidly enter Southeast Asia. This emphasized a need for continued high-level surveillance of vectors and viruses at strategic locations in the north of Australia The expansion of routine characterization and classification of BTV to a whole genome approach is recommended, to better monitor the presence and level of establishment of novel Western topotype segments within the Australian episystem.

Project description:Hematologic malignancies are among the most common cancers, and understanding their incidence and death is crucial for targeting prevention, clinical practice improvement, and research resources appropriately. Here, we investigated detailed information on hematological malignancies for the period 1990-2019 from the Global Burden of Disease study. The age-standardized incidence rate (ASIR), the age-standardized death rate (ASDR), and the corresponding estimated annual percentage changes (EAPC) were calculated to assess temporal trends in 204 countries and territories over the past 30 years. Globally, incident cases of hematologic malignancies have been increasing since 1990, reaching 1343.85 thousand in 2019, but the ASDR for all types of hematologic malignancies has been declining. The ASDR for leukemia, multiple myeloma, non-Hodgkin lymphoma, and Hodgkin lymphoma were 4.26, 1.42, 3.19, and 0.34 per 100,000 population in 2019, respectively, with Hodgkin lymphoma showing the most significant decline. However, the trend varies by gender, age, region, and the country's economic situation. The burden of hematologic malignancies is generally higher in men, and this gender gap decreases after peaking at a given age. The regions with the largest increasing trend in the ASIR of leukemia, multiple myeloma, non-Hodgkin lymphoma, and Hodgkin lymphoma were Central Europe, Eastern Europe, East Asia, and Caribbean, respectively. In addition, the proportion of deaths attributed to high body-mass index continued to rise across regions, especially in regions with high socio-demographic indices (SDI). Meanwhile, the burden of leukemia from occupational exposure to benzene and formaldehyde was more widespread in areas with low SDI. Thus, hematologic malignancies remain the leading cause of the global tumor burden, with growing absolute numbers but sharp among several age-standardized measures over the past three decades. The results of the study will inform analysis of trends in the global burden of disease for specific hematologic malignancies and develop appropriate policies for these modifiable risks.

Project description:Outbreaks of the European Bluetongue virus (BTV) serotype 8 (BTV-8), which are characterized by activity cycles separated by years of inactivity, may be influenced by genetic changes of the virus or by herd immunity. BTV activity in Israel is characterized by similar dynamics, but differs from European countries in its vector population, environmental conditions, and lack of cattle vaccination against this serotype. Comparison of these two geographical systems and characterization of their epidemiological connection is therefore of high interest in-order to better understand the factors influencing BTV-8 evolution. BTV-8, closely related to the European strain, was introduced to Israel in 2008. It was at the center of BT outbreaks in 2010 and 2015-2016 and thereafter was lastly isolated in Israel in 2019. We performed genetic analyses of twelve BTV-8 Israeli strains isolated between 2008 and 2019 and compared them with published sequences of BTV-8 isolated in other countries. The analysis revealed a single introduction of BTV-8 into Israel and thereafter extensive occurrence of genomic drifts and multiple reassortments with local BTV strains. Comparison of the Israeli and Cypriot BTV-8 from 2015 to 2016 suggests transmission of the virus between the two countries and a separate and parallel development from European or other Israeli BTV-8 strains. The parallel development of other BTV-8 strains was demonstrated by the identification of the Israeli BTV-8 ISR-1194/1/19 strain, which exhibited common origin with reassorted Israeli BTV-8 strains from 2010 and additional reassortment of seven segments. In order to reveal the source of BTV-8 introduction into Israel we performed BEAST analysis which showed that a probable common ancestor for both European and Israeli BTV-8 presumably existed in 2003-2004. In 2019, a possible new introduction occurred in Israel, where a novel BTV-8 strain was detected, sharing ~95% identity by segments 2 and 6 with Nigerian BTV-8NIG1982/07 and European-Middle Eastern strains. The results of the study indicate that Israel and neighboring countries consist a separate environmental and evolutionary system, distinct from European ones.

Dataset Information

Evolution of bluetongue virus serotype 1 in northern Australia over 30 years.

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Evolution of bluetongue virus serotype 1 in northern Australia over 30 years.

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