Highly virulent strains of the avian infectious bursal disease virus: Literature review and epidemiological situation

Cette revue se focalise sur le virus très virulent de la bursite infectieuse aviaire (vvIBDV). Ce virus est présent dans le monde entier, causant des pertes économiques considérables représentant une menace pour l'industrie de la volaille. L’émergence des formes aiguës de la maladie a radicalement changé l’épidémiologie de l’IBD. Bien que leur origine soit encore à l’étude, les vvIBDV se sont répandus dans le monde entier de manière explosive mais conservée. Cela pose la question de l’origine des vvIBDV, de la possibilité d’existence de réservoirs et de l'émergence possible de nouvelles lignées distinctes dans l’avenir. Il est devenu évident que les acides aminés dans la région hyper-variable de la protéine virale VP2 constitue une base moléculaire de la variation antigénique, mais aucune mutation qui détermine la pathogénicité n’a été identifiée. Ces marqueurs moléculaires des souches vvIBDV doivent être considérés davantage comme une évolution commune plutôt que marqueurs de virulence. Le seul critère valable pour la classification des souches d’IBDV en tant que «pathotype» doit faire référence à leur virulence clinique. Cet article présente une synthèse des caractéristiques moléculaires, phylogénétiques, épidémiologiques, antigéniques et pathotypiques des souches très virulentes du virus de la bursite infectieuse aviaire. Mots clés: Revue bibliographique, vvIBDV, moléculaire, épidémiologie, phylogénie, pathotypeThis review focuses on the very virulent viral avian infectious bursal disease virus (vvIBDV). This virus was first described in the United States about 30 years ago, it quickly spread around the world, causing considerable economic losses; after three decades, it still poses a threat to the poultry industry. The emergence of acute forms of the disease has radically changed the epidemiology of IBD. Although their origin is still under study, vvIBDV has spread throughout the world in an explosive but conservative manner. This raises the question of the origin of vvIBDV, the possibility of existence of reservoirs and the possible emergence of new distinct lineages in the future. It has become clear that the amino acids in the hyper-variable region of the VP2 viral protein constitute a molecular basis for antigenic variation, but no mutation that determines pathogenicity has been identified. These molecular markers of the vvIBDV strains should be considered more as a common evolution than as markers of virulence. This article presents a synthesis of the molecular, phylogenetic, epidemiological, antigenic and pathotypic characteristics of the very virulent strains of IBDV. Keywords: Review, vvIBDV, molecular, phylogeny, epidemiology, pathotype

Zootechnical performance study and susceptibility to Avian Influenza virus H9N2 in a breed of crossbred chicken with intermediate growth

La viande de volaille constitue la protéine d’origine animale la plus consommée en raison de son prix abordable par rapport aux autres denrées animales. De ce fait, le secteur avicole connait constamment des progrès améliorant la productivité et la qualité organoleptique des viandes de volaille.  Pour satisfaire aux enjeux de la sécurité alimentaire et l’exigence des citoyens et consommateurs, le présent travail consiste à étudier et comparer les performances zootechniques ainsi que la sensibilité au virus H9N2 de poulet croisé à croissance intermédiaire (I), par rapport à deux races de poulets à croissance rapide (R) et à croissance lente (L). Les résultats de l’étude ont montré des performances zootechniques de la race I à croissance intermédiaire similaire à celles du poulet à croissance rapide R. En effet, le lot témoin I a enregistré un GMH significativement élevé à celui du lot témoin L. L’indice de consommation du lot R et I est 50% plus bas que celui du poulet L. Concernant l’infection expérimentale par le virus H9N2, le groupe de poulet I et R ont présenté les signes cliniques et les lésions macroscopiques les plus sévères et accentués par rapport aux poulets du lot L à croissance lente. Mots clés : infection H9N2, croissance rapide, croissance intermédiaire, performance zootechniquePoultry meat is the most widely consumed animal protein due to its low price compared to other animal products. However, the poultry sector is constantly experiencing progress improving the productivity and organoleptic quality of poultry meat. To responds the challenges of food security and the requirements of citizens and consumers, the present work consists to study the zootechnical performances as well as the sensitivity to the H9N2 virus of cross-breed chicken with intermediate growth (I), compared to two breeds fast growing (R) and slow growing (L) chickens. The results of the study showed zootechnical performances of race I with intermediate growth similar to those of fast growing chicken R. Indeed, the control group I recorded a GMH significantly elevated to that of the control group L. The index consumption of lot R and I is 50% lower than that of chicken L. Concerning the experimental infection with the H9N2 virus, the group of chicken I and R presented the most severe and accentuated clinical signs and gross lesions compared to chickens of the slow breed L. Keywords: infection, H9N2, rapid growth, intermediate growth, slow growth, zootechnical performanc

Prévalence de la maladie de la bronchite infectieuse aviaire au Maroc entre Juin 2018 et Avril 2019

Avian infectious bronchitis (IB) is mainly an upper respiratory tract infection caused by infectious bronchitisvirus (IBV) belonging to the Coronaviridae family. This work aims to assess the prevalence of IBV in different regions of Morocco using real-time RT-PCR, in order to better understand the epidemiological situation of the disease in these regions. Epidemiological analyses have shown that the IBV circulates with a high prevalence of 61% between 2018 and 2019, thus, the results obtained were valued and evaluated by a statistical study using the SPSS version 13 (Statistical Package for the Social Sciences). IB circulated with distinct prevalence’s in the different regions of Morocco, but this difference was not statistically significant. A peak of positivity was found in the BeniMellal-Khenifra, Draa-Tafilalet, and Souss-Massa regions. On the other hand, a very high vaccination rate against IB (90% of farms) in Morocco has been observed. Keywords: Avian infectious bronchitis, real-time RT-PCR, Prevalence, MoroccoLa bronchite infectieuse aviaire (BI) est principalement une infection des voies respiratoires supérieures causée par le virus de la bronchite infectieuse aviaire (IBV) appartenant à la famille des Coronaviridae. Le présent travail a pour objectif d’évaluer la prévalence de l’IBVdans sept différentes régions du Maroc en utilisant la RT-PCR en temps réel, afin de mieux connaitre la situation épidémiologique de la maladie dans ces régions. L’analyse épidémiologique a montré que l’IBV a circulé avec une forte prévalence de 61% entre 2018 et 2019, ainsi, les résultats obtenues ont été valorisées et évaluées par une étude statistique via la version 13 du logiciel SPSS (Statistical Package for the Social Sciences). L’infection à l’IBV a circulé avec des prévalences distinctes dans les différentes régions du Maroc, mais cette différence n’était pas statistiquement significative. Un pic de positivité a été mis en évidence dans les régions BeniMellal-Khenifra, Draa-Tafilalet, et Souss-Massa. D’autre part, un taux de vaccination très élevé contre la BI (90% des élevages) au Maroc a été constaté. Mots clés: Bronchite infectieuse aviaire, RT-PCR en temps réel, Prévalence, Maro

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The Pathogenic Effects of Moroccan Very Virulent Infectious Bursal Disease Virus on Lymphoid Organs: A Comparative Study in Conventional Broiler and Specific-Pathogen-Free Chickens

Infectious bursal disease (IBD) is a major immunosuppressive disease affecting young chickens, and causes significant economic losses to the poultry industry. This work represents the first pathogenicity assessment of Moroccan very virulent IBD virus. Molecular characterization and sequence analysis of this isolate previously identified specific substitutions, including seven amino acid substitutions in segment A, and I472L and E688D in segment B, specific and unique to Moroccan vvIBDV strains. Two chicken lines, broiler and specific-pathogen-free (SPF) chickens, were inoculated via the occulonasal route with 0.2 mL of the 105EID50 /mL viral solution of the IB19 vvIBDV strain at 29 days of age. Experimental monitoring was carried out for 10 days post-challenge (dpc). Clinical signs started on the second dpc, with peak severity observed between 3 and 6 dpc. The total mortality rate reached 10% in broilers (group G1) and 93% in SPF chickens (G3). Macroscopic lesions in G1 broilers included marked hypertrophy of the bursa of Fabricius (BF), followed by very pronounced atrophy, while macroscopic examinations of deceased SPF birds (G3) revealed very hemorrhagic BF with a black cherry appearance in 80% of dead birds. The mean Bursa/Body Index (BBI) of challenged broilers (G1) showed a decrease of 46% compared to the control group (G2), indicating bursal atrophy. Microscopic lesions in the BF consisted mainly of inflammation, with severe lymphoid depletion of the follicles in challenged G3 SPF birds. This in vivo study of Moroccan vvIBDV demonstrated a distinctive virulence profile, and confirmed its classification as a very virulent strain with substantial disease-causing potential. It is crucial to obtain comprehensive knowledge of the prevalence, emergence, pathogenicity, and control of Moroccan IBDV strains

Pathogenicity and Effects on Lymphoid Organs of Recent Moroccan Very Virulent Infectious Bursal Disease Virus in Broilers and SPF Chickens

Abstract The aim of the current study is to evaluate the pathogenicity of recent infectious bursal disease virus (IBDV) (1/chicken/Morocco/IB19/2017) genetically characterized as vvIBDV belonging to genogroup 3.Two chicken lines, broiler and specific-pathogen-free (SPF) chickens, were inoculated by occulonasal route with 0.2 ml of the 105EID50 /ml of viral solution of IB19 vvIBDV strain at 29 days of age. The experimental monitoring was carried out during 10 days post challenge (dpc). The clinical signs stared on day 2 pc with maximum severity observed between 3 and 6 dpc. The total mortality rate reached 10% in broilers (group G1) and 93% in SPF (G3). The macroscopic lesions in broilers G1 was a marked hypertrophy of the bursa of Fabricius (BF) with slight haemorrhage observed between 2 to 4 dpc, followed by very pronounced atrophy observed on the 5 dpc. The post-mortem examinations of dead SPF birds (G3) revealed on 3 dpc very haemorrhagic BF with black cherry appearance in 80 % of dead birds. The mean Bursa/Body Index (BBI) of challenged broilers (G1) showed a decrease of 46% on day 9 pc compared to broilers control group (G2) indicating bursal atrophy. The microscopic lesions found in the BF on 3 dpc consisted mainly of inflammation with severe lymphoid depletion of the follicles. The evaluation of recent vvIBDV outbreak is very important to understand its epidemiology and will contribute to the efficient prevention and control of IBD.</jats:p

Avian Influenza a H9N2 Viruses in Morocco, 2018&ndash;2019

Low pathogenic H9N2 avian influenza (LPAI H9N2) is considered one of the most important diseases found in poultry (broiler, laying hens, breeding chickens, and turkeys). This infection causes considerable economic losses. The objective of this work was to monitor and assess the presence of avian influenza virus (AIV) H9N2 in eight different regions of Morocco using real-time RT-PCR, and to assess the phylogenetic and molecular evolution of the H9N2 viruses between 2016 and 2019. Field samples were collected from 108 farms suspected of being infected with LPAI H9N2 virus. Samples were analyzed using H9N2-specific real-time RT-PCR. Highly positive samples were subjected to virus isolation and seven isolates were fully sequenced. Low pathogenic H9N2 avian influenza virus was introduced in Morocco in 2016. We show that in 2018&ndash;2019, the virus was still present irrespective of vaccination status. Phylogenetic and molecular analyses showed mutations related to virulence, although our viruses were related to 2016 Moroccan viruses and grouped in the G1 lineage. Specific amino acid substitutions were identified in Moroccan H9N2 viruses that are believed to lead to increased resistance to antiviral drugs

Avian Influenza a H9N2 Viruses in Morocco, 2018–2019

Low pathogenic H9N2 avian influenza (LPAI H9N2) is considered one of the most important diseases found in poultry (broiler, laying hens, breeding chickens, and turkeys). This infection causes considerable economic losses. The objective of this work was to monitor and assess the presence of avian influenza virus (AIV) H9N2 in eight different regions of Morocco using real-time RT-PCR, and to assess the phylogenetic and molecular evolution of the H9N2 viruses between 2016 and 2019. Field samples were collected from 108 farms suspected of being infected with LPAI H9N2 virus. Samples were analyzed using H9N2-specific real-time RT-PCR. Highly positive samples were subjected to virus isolation and seven isolates were fully sequenced. Low pathogenic H9N2 avian influenza virus was introduced in Morocco in 2016. We show that in 2018–2019, the virus was still present irrespective of vaccination status. Phylogenetic and molecular analyses showed mutations related to virulence, although our viruses were related to 2016 Moroccan viruses and grouped in the G1 lineage. Specific amino acid substitutions were identified in Moroccan H9N2 viruses that are believed to lead to increased resistance to antiviral drugs.</jats:p