Salmonella enterica subsp. enterica serovar Gallinarum (SG) has two distinct biovars, Pullorum and Gallinarum. They are bacterial pathogens that exhibit host specificity for poultry and aquatic birds, causing severe systemic diseases known as fowl typhoid (FT) and Pullorum disease (PD), respectively. The virulence mechanisms of biovars Gallinarum and Pullorum are multifactorial, involving a variety of genes and pathways that contribute to their pathogenicity. In addition, these serovars have developed resistance to various antimicrobial agents, leading to the emergence of multidrug-resistant strains. Due to their economic and public health significance, rapid and accurate diagnosis is crucial for effective control and prevention of these diseases. Conventional methods, such as bacterial culture and serological tests, have been used for screening and diagnosis. However, molecular-based methods are becoming increasingly important due to their rapidity, high sensitivity, and specificity, opening new horizons for the development of innovative approaches to control FT and PD. The aim of this review is to highlight the current state of knowledge on biovars Gallinarum and Pullorum, emphasizing the importance of continued research into their pathogenesis, drug resistance and diagnosis to better understand and control these pathogens in poultry farms.

Outbreaks of inclusion body hepatitis have emerged in Morocco since 2013 and has resulted in significant economic losses to poultry farms. Three isolates of the causative virus, Fowl adenonovirus (FAdV)were characterized from chickens with IBH, but their pathogenicity has never been investigated. In this work, the pathogenicity of an isolate FAdV 11 (MOR300315 strain) was evaluated by inoculating a group of 40 SPF chickens at 3 days of age by oral route. A group of 40 chicks injected with phosphate-buffered saline solution was used as a control group. The infected chickens showed decreased weight gain from 3dpi. Necropsy displayed pallor and enlargement in liver, swelling and slight hemorrhage in kidney and spleen at 6 dpi. Histopathological changes were mainly characterized by severe and extensive hepatic necrosis associated with the presence of basophilic intra-nuclear inclusion bodies within hepatocytes. The FAdV was reisolated in chicken embryo fibroblast cell culture from liver tissue homogenate of infected chicken from 3 to 6 dpi. Viral DNA was detected by PCR in liver, kidney, spleen and cloacal swabs from 3 to 13 dpi. Antibody response against inoculated FAdV was appeared from 9 dpi. These results confirmed that the FAdV 11 strain is pathogenic in chicken. This study is the first experimental infection of FAdV 11 in chicken in Morocco, which increase our understanding of its pathogenicity in chickens and indicate that preventive measures against FAdV infection in poultry farms should be implemented in Morocco.

The H9N2 virus continues to spread in wild birds and poultry worldwide. At the beginning of 2016, the H9N2 Avian influenza virus (AIV) was detected in Morocco for the first time; despite the implementation of vaccination strategies to control the disease, the virus has become endemic in poultry in the country. The present study was carried out to investigate the origins, zoonotic potential, as well as the impact of vaccination on the molecular evolution of Moroccan H9N2 viruses. Twenty-eight (28) H9N2 viruses collected from 2016 to 2021 in Moroccan poultry flocks were isolated and their whole genomes sequenced. Phylogenetic and evolutionary analyses showed that Moroccan H9N2 viruses belong to the G1-like lineage and are closely related to viruses isolated in Africa and the Middle East. A high similarity among all the 2016–2017 hemagglutinin sequences was observed, while the viruses identified in 2018–2019 and 2020–2021 were separated from their 2016–2017 ancestors by long branches. Mutations in the HA protein associated with antigenic drift and increased zoonotic potential were also found. The Bayesian phylogeographic analyses revealed the Middle East as being the region where the Moroccan H9N2 virus may have originated, before spreading to the other African countries. Our study is the first comprehensive analysis of the evolutionary history of the H9N2 viruses in the country, highlighting their zoonotic potential and pointing out the importance of implementing effective monitoring systems.

Avian influenza viruses pose significant threats to both the poultry industry and public health worldwide. Among them, the H9N2 subtype has gained substantial attention due to its high prevalence, especially in Asia, the Middle East, and Africa; its ability to reassort with other influenza viruses; and its potential to infect humans. This study presents a comprehensive phylogenetic and molecular analysis of H9N2 avian influenza viruses circulating in Morocco from 2021 to 2023. Through an active epidemiological survey, a total of 1140 samples (trachea and lungs) and oropharyngeal swabs pooled into 283 pools, collected from 205 farms located in 7 regions of Morocco known for having a high density of poultry farms, were analyzed. Various poultry farms were investigated (159 broiler farms, 24 layer farms, 10 breeder farms, and 12 turkey breeder farms). A total of 21 AI H9N2 strains were isolated, and in order to understand the molecular evolution of the H9N2 avian influenza virus, their genetic sequences were determined using the Sanger sequencing technique. Phylogenetic analysis was performed using a dataset comprising global H9N2 sequences to determine the genetic relatedness and evolutionary dynamics of the Moroccan strains. The results revealed the continued circulation and diversification of H9N2 avian influenza viruses in Morocco during the study period. Real-time RT-PCR showed a positivity rate of 35.6% (73/205), with cycle threshold values ranging from 19.2 to 34.9. The phylogenetic analysis indicated that all Moroccan strains belonged to a G1-like lineage and regrouped into two distinct clusters. Our newly detected isolates aggregated distinctly from the genotypes previously isolated in Morocco, North and West Africa, and the Middle East. This indicats the potential of virus evolution resulting from both national circulation and cross-border transmission. A high genetic diversity at both nucleotide and amino-acid levels was observed among all the strains isolated in this study, as compared to H9N2 strains isolated in Morocco since 2016, which suggests the co-circulation of genetically diverse H9N2 variants. Newly discovered mutations were detected in hemagglutinin positions 226, 227, and 193 (H3 numbering), which highlights the genetic evolution of the H9N2 AIVs. These findings contribute to our understanding of the evolution and epidemiology of H9N2 in the region and provide valuable insights for the development of effective prevention and control strategies against this emerging avian influenza subtype.

Síndrome de erosión y ulceración de la molleja en parvadas avícolas marroquíes y caracterización molecular de los adenovirus aviares (FAdV). El síndrome de erosión y ulceración de la molleja (GEUS) es causado por un adenovirus del pollo de serotipo 1 (FAdV-1) y se reportó por primera vez en gallinas de postura en Japón en 1993. Este síndrome se ha convertido en una epizootia en Marruecos desde 2014, causando importantes pérdidas económicas a la industria avícola, pero no se ha confirmado la participación de ningún adenovirus del pollo. Por lo tanto, el objetivo de este trabajo fue evaluar los casos de GEUS ocurridos en el país y determinar el papel de adenovirus del pollo en su presentación. Las investigaciones se basaron en una reevaluación retrospectiva de secciones de tejido y bloques de parafina de mollejas e hígados de casos de GEUS entre 2014 y 2021, junto con una investigación prospectiva de casos en el año 2022. Las mollejas y los hígados se fijaron en formalina al 10% amortiguada y neutra para exámenes histopatológicos de acuerdo con métodos estándar y se almacenaron a -20 C para análisis moleculares. Después de la desparafinación, las secciones de tejido de 10 µm de espesor junto con órganos frescos se sometieron a extracción de ADN utilizando un estuche comercial. Para realizar un método de PCR convencional, se utilizó un par de iniciadores específicos para el gene de hexon de los adenovirus del pollo, mientras que, para el método de PCR en tiempo real, se empleó un par de iniciadores dirigidos al gene 52K. En total, se evaluaron 24 casos de parvadas con la presentación característica del síndrome de erosión y ulceración de la molleja entre los años 2014 y 2022. Se trató de nueve casos de pollos de engorde con edades comprendidas entre los 11 y 39 días, 11 casos de ponedoras con una edad de entre 17 y 29 semanas, dos casos en reproductoras pesadas de 10 y 27 semanas, y dos lotes de pavitos de 22 y 23 días. En la mayoría de los casos, las lesiones microscópicas fueron consistentes con una ventriculitis ulcerativa y linfoplasmocítica, y se identificaron cuerpos de inclusión intranucleares virales patognomónicos dentro de células epiteliales degeneradas en cuatro casos de parvadas de pollos de engorde, cuatro casos de ponedoras y un caso en reproductoras y por lo tanto, fueron altamente sugestivos de la infección por adenovirus de pollo. Entre los nueve casos que fueron positivos en el examen histopatológico, se encontró que seis casos fueron positivos para adenovirus de pollo mediante PCR; otros cuatro casos fueron negativos a la histología pero positivos a la presencia de adenovirus del pollo mediante PCR. Además, se realizó un análisis de secuenciación que proporcionó la evidencia inicial del papel de adenovirus del pollo especie A como causante del síndrome de erosión y ulceración de la molleja en la avicultura de Marruecos. Además, se realizó un análisis filogenético para facilitar una comparación entre las cepas investigadas en este estudio y las identificadas en diversas regiones geográficas y en varios períodos de tiempo.