scholarly journals Phylodynamic and Recombination Analyses of Avian Infectious Bronchitis GI-23 Reveal a Widespread Recombinant Cluster and New Among-Countries Linkages

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3182
Author(s):  
Mohamed H. Houta ◽  
Kareem E. Hassan ◽  
Matteo Legnardi ◽  
Claudia M. Tucciarone ◽  
Ahmed S. Abdel-Moneim ◽  
...  

Infectious bronchitis virus GI-23 lineage, although described approximately two decades ago in the Middle East, has recently drawn remarkable attention and is considered an “emerging” lineage due to its current spread to several other regions, including Europe. Despite the relevance, no comprehensive studies are available investigating its epidemiologic and evolutionary pattern. The present phylodynamic study was designed to fill this gap, benefitting from a collection of freely available GI-23 sequences and ad-hoc generated European ones. After a relatively ancient origin in the Middle East, likely in the first half of the previous century, GI-23 circulated largely undetected or underdiagnosed for a long time in this region, likely causing little damage, potentially because of low virulence coupled with limited development of avian industry in the considered years and regions and insufficient diagnostic activity. The following development of the poultry industry and spread to other countries led to a progressive but slow increase of viral population size between the late ‘90s and 2010. An increase in viral virulence could also be hypothesized. Of note, a big recombinant cluster, likely originating in the Middle East but spreading thereafter, especially to Europe through Turkey, demonstrated a much-marked increase in viral population size compared to previously circulating variants. The extensive available GI-23 sequence datasets allowed to demonstrate several potential epidemiological links among African, Asian, and European countries, not described for other IBV lineages. However, differently from previously investigated IBV lineages, its spread appears to primarily involve neighbouring countries and those with strong economic and political relationships. It could thus be speculated that frequent effective contacts among locations are necessary for efficient strain transmission. Some countries appear to play a major role as a “bridge” among less related locations, being Turkey the most relevant example. The role of vaccination in controlling the viral population was also tentatively evaluated. However, despite some evidence suggesting such an effect, the bias in sequence and data availability and the variability in the applied vaccination protocols prevent robust conclusions and warrant further investigations.

2013 ◽  
Vol 45 (03) ◽  
pp. 822-836 ◽  
Author(s):  
Pierre Collet ◽  
Servet Martínez ◽  
Sylvie Méléard ◽  
Jaime San Martín

We introduce two stochastic chemostat models consisting of a coupled population-nutrient process reflecting the interaction between the nutrient and the bacteria in the chemostat with finite volume. The nutrient concentration evolves continuously but depends on the population size, while the population size is a birth-and-death process with coefficients depending on time through the nutrient concentration. The nutrient is shared by the bacteria and creates a regulation of the bacterial population size. The latter and the fluctuations due to the random births and deaths of individuals make the population go almost surely to extinction. Therefore, we are interested in the long-time behavior of the bacterial population conditioned to nonextinction. We prove the global existence of the process and its almost-sure extinction. The existence of quasistationary distributions is obtained based on a general fixed-point argument. Moreover, we prove the absolute continuity of the nutrient distribution when conditioned to a fixed number of individuals and the smoothness of the corresponding densities.


2021 ◽  
Author(s):  
Hoda R.K. Nejad

With the emergence of wireless devices, service delivery for ad-hoc networks has started to attract a lot of attention recently. Ad-hoc networks provide an attractive solution for networking in the situations where network infrastructure or service subscription is not available. We believe that overlay networks, particularly peer-to-peer (P2P) systems, is a good abstraction for application design and deployment over ad-hoc networks. The principal benefit of this approach is that application states are only maintained by the nodes involved in the application execution and all other nodes only perform networking related functions. On the other hand, data access applications in Ad-hoc networks suffer from restricted resources. In this thesis, we explore how to use Cooperative Caching to improve data access efficiency in Ad-hoc network. We propose a Resource-Aware Cooperative Caching P2P system (RACC) for data access applications in Ad-hoc networks. The objective is to improve data availability by considering energy of each node, demand and supply of network. We evaluated and compared the performance of RACC with Simple Cache, CachePath and CacheData schemes. Our simulation results show that RACC improves the lay of query as well as energy usage of the network as compared to Simple Cache, CachePath and CacheData.


2016 ◽  
Vol 6 (4) ◽  
pp. 13-19
Author(s):  
Niroj Kumar ◽  
Bikram Keshari ◽  
Sarojananda Mishra
Keyword(s):  
Ad Hoc ◽  

Author(s):  
Anirban Mondal ◽  
Sanjay Kumar Madria ◽  
Masaru Kitsuregawa

This paper proposes CADRE (Collaborative Allocation and De-allocation of Replicas with Efficiency), which is a dynamic replication scheme for improving the typically low data availability in dedicated and cooperative mobile ad-hoc peer-to-peer (M-P2P) networks. In particular, replica allocation and de-allocation are collaboratively performed in tandem to facilitate effective replication. Such collaboration is facilitated by a hybrid super-peer architecture in which some of the mobile hosts act as the ‘gateway nodes’ (GNs) in a given region. GNs facilitate both search and replication. The main contributions of CADRE are as follows. First, it facilitates the prevention of ‘thrashing’ conditions due to its collaborative replica allocation and de-allocation mechanism. Second, it considers the replication of images at different resolutions to optimize the usage of the generally limited memory space of the mobile hosts (MHs). Third, it addresses fair replica allocation across the MHs. Fourth, it facilitates the optimization of the limited energy resources of MHs during replication. The authors’ performance evaluation demonstrates that CADRE is indeed effective in improving data availability in M-P2P networks with significant reduction in query response times and low communication traffic during replication as compared to a recent existing scheme as well as a baseline approach, which does not consider any replication.


Author(s):  
Kabiru Ishola Genty ◽  
Foluso I. Jayeoba ◽  
Mike O. Aremo ◽  
Tinuke M. Fapohunda ◽  
Rafiu A. Bankole

The onset, spread, control measures, and the behaviour of society, government, and businesses have far reaching implications—social, economic, and legal—for the immediate and future of employment relations and human resource management in Nigerian organisations. This chapter, drawing from available COVID-19 literature, ILO, and WHO protocols, examined various concerns and challenges posed by ongoing COVID-19 pandemic and the regimes of measures which are modeled after developed economies of the world but are at best ad-hoc, panicky, ill-digested and their operations execution not based on empirical/objective assessment. COVID-19 has evidently brought job losses and unprecedented changes in work modes and some of the lessons and fallouts may live with us for a long time. Post-COVID-19 economic recovery though expected to be slow will leave the workplace and society with routines and rituals, lessons to learn and corrections to be made, not to avert future pandemics but to manage it in more precise manner with less panic and greater forthrightness.


2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Abdullah I. A. Al-Mubarak ◽  
Anwar A. G. Al-Kubati

Avian infectious bronchitis virus (IBV) is an evolving and dynamic virus that causes major economic losses for the poultry industry worldwide. Continuous evolution and emergence of new variants of this virus are the major challenges for controlling the disease with routine vaccination. Successful vaccination usually requires the use of a homologous vaccine, which in turn necessitates continuous investigation of the circulating strains. Herein, we performed a reverse transcriptase-polymerase chain reaction- (RT-PCR-) based investigation in broiler chicken flocks of the Eastern Region of Saudi Arabia. IBV was detected in 36.5% of the tested flocks (42 out of 115) from January 2012 to March 2014. Direct sequencing of hypervariable region-3 (HVR-3) of the Spike (S)-1 gene was performed, followed by phylogenetic analysis to determine the circulating IBV genotypes. Four lineages appear to coexist in this region, including the GI-13 or 4/91 IBV (31%), GI-16 or CK/CH/LDL/97I IBV (28.6%), GI-1 or Mass IBV (19%), and GI-23 or Middle East IBV (21.4%). The latter lineage include two subgroups: IS/720/99 IBV (16.7%) and IS/Variant2/98 IBV (4.7%). Some of the detections made in the 4/91 and Mass lineages are expected to belong to the vaccine strains. Lineages without a homologous vaccine in use (CK/CH/LDL/97I and Middle East) represent 50% of the isolates recovered in this study. Based on identity with the vaccine sequences, field observations, and frequent detection, these two lineages appear to be out of coverage of the IBV vaccines used in Saudi Arabia. This is the first time to identify Middle East lineage (IS/720/99 IBV and IS/Variant2/98 IBV) in the Eastern Region of Saudi Arabia.


Zootaxa ◽  
2011 ◽  
Vol 2746 (1) ◽  
pp. 20 ◽  
Author(s):  
CLEMENS GROSSER ◽  
HASKO F. NESEMANN ◽  
VLADIMIR PEŠIĆ

The new species described here has, for a long time, been confused with Dina stschegolewi (Lukin & Epshtein, 1960), a species described from Krym (the Crimean Peninsula, Ukraine). Both species are similar in having rows of yellow spots on the dorsal surface. As the latter species had been poorly defined in the past, all yellow spotted specimens of the genus Dina Blanchard, from the area of the Near and Middle East, were attributed to Dina stschegolewi (Rückert 1985, Nesemann 1993, Nesemann & Neubert 1999). Prof. V. M. Epshtein (Wuppertal/Germany, oral communication) suspected that the specimens attributed to Dina stschegolewi by Nesemann (1993) and Nesemann & Neubert (1999) differed from the species from Krym. Furthermore, Grosser & Pešić (2006) mentioned that populations of Dina stschegolewi sensu Nesemann, 1993 most probably belong to a new species.


2012 ◽  
Vol 6 (3) ◽  
pp. 831-852 ◽  
Author(s):  
Peter G. M. van der Heijden ◽  
Joe Whittaker ◽  
Maarten Cruyff ◽  
Bart Bakker ◽  
Rik van der Vliet

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