Publications by authors named "Saâdia Nassik"

5 Publications

  • Page 1 of 1

Protective Efficacy Evaluation of Four Inactivated Commercial Vaccines Against Low Pathogenic Avian Influenza H9N2 Virus Under Experimental Conditions in Broiler Chickens.

Avian Dis 2021 09;65(3):351-357

Unité de Pathologie Aviaire, Département de Pathologie et Santé Publique Vétérinaire, Institut Agronomique et Vétérinaire Hassan II, Rabat, Morocco (10000),

Avian influenza vaccines are commonly used in the poultry industry. The objective of this study was to compare, under experimental conditions, the protective efficacy of four imported commercial inactivated H9N2 vaccines (A, B, C, and D) in broiler chickens. A total of 150 one-day-old chicks were divided into six groups: four experimental groups, each containing 30 chicks, received one of the vaccines (A, B, C, or D) delivered in a 0.3-ml dose subcutaneously at 1 day of age, whereas the control, Group T, was not vaccinated but challenged and Group E was kept unvaccinated and unchallenged. At 21 days postvaccination, Groups A, B, C, D, and T were challenged with 10 embryo infective dose 50% of A/Chicken/Morocco/01/2016 (H9N2). All chicks were observed daily for clinical signs during the 12 days postchallenge (dpc). At 5 and 12 dpc, chicks were euthanatized for necropsy examination. Blood samples were collected weekly for serologic analysis and oropharyngeal swabs were collected for virus detection by real-time RT-PCR. Respiratory signs started at 48 hr pc and maximum severity was observed on 9 dpc. Chiefly, the birds vaccinated with vaccine B showed significantly more respiratory signs than did their counterparts. Serologic analysis revealed that the sera of Groups A and D birds showed a decrease in antibody (Ab) levels up to day 26; then a slight increase of Ab level was observed until day 31, while Group B and C birds showed a stabilization of the titers from day 21 until the end of the experiment. The viral shedding rate was significantly lower in Groups C and A (40%-50% of the birds shed virus for <7 days) compared with other challenged groups (60%-75% of the birds shed virus for ≥9 days). This experiment illustrated that vaccination applied on the first day in the hatchery with the four vaccines tested did not provide an acceptable protection against H9N2 in comparison with the controls that did not receive any vaccine. However, at first glance, we might favor vaccines A and C for their ability to reduce and shorten viral shedding as compared with vaccines B and D.
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http://dx.doi.org/10.1637/aviandiseases-D-21-00015DOI Listing
September 2021

Pathogenesis of Avian Influenza Virus Subtype H9N2 in Turkeys and Evaluation of Inactivated Vaccine Efficacy.

Avian Dis 2021 03;65(1):46-51

Unité de Pathologie Aviaire, Département de Pathologie et Santé Publique Vétérinaire, Institut Agronomique et Vétérinaire Hassan II, Rabat, Morocco.

Avian influenza H9N2 viruses circulate in all types of poultry species, including turkeys, and cause significant losses for the poultry industry in many parts of the word. The aim of this study was to assess the pathogenesis of the Moroccan avian influenza virus (AIV) H9N2 under experimental conditions in turkeys and the protection efficacy of an inactivated commercial vaccine against AIV H9N2. Unvaccinated turkeys showed marked depression sinusitis, respiratory distress characterized by bronchiolar and tracheal rales of moderate severity, and a mortality rate of 50%. Postmortem examinations of dead and euthanatized birds revealed the presence of fibrinous tracheitis and airsacculitis lesions. Vaccination reduced the mortality rate to 20%. Vaccinated birds recovered at day 10 postchallenge, and only 12.5% (1/8) and 37.5% of birds still displayed fibrinous and nonfibrinous airsacculitis lesions, respectively, at day 15 postinoculation. Viral shedding in cloacal and tracheal swabs was lower in vaccinated than in control birds. Although viral RNA was detected in the cloacal swabs of all unvaccinated turkeys at day 3 postinoculation, only 50% of the vaccinated turkeys were positive for virus detection. At day 11 postinoculation, no viral RNA was detected in oropharyngeal swabs of vaccinated turkeys, whereas 40% of the unvaccinated turkeys were still shedding virus.
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http://dx.doi.org/10.1637/aviandiseases-D-20-00067DOI Listing
March 2021

First Report of Isolation of from Layer Chickens in Morocco with Decrease in Laying Performance.

Avian Dis 2019 12;63(4):727-730

Clinic for Poultry and Fish Medicine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna 1210, Austria.

is a genus of the family of . It is well known as a commensal inhabitant of the respiratory and reproductive tract of healthy chickens. But in the last years, is increasingly reported in field cases with a decrease in laying performance due to infections of the reproductive tract. The aim of the present study was to investigate the implication of infection in layer flocks facing a decrease in laying performance in Morocco. Birds were received from five different laying hen farms in two regions in Morocco showing a drop of egg production. Necropsy revealed 46.1 % (24/52) of sampled birds showed variable lesions in ovaries, salpinx, and trachea. In fact, 24 birds were affected by salpingitis, 18 by oophoritis, and 11 birds by atrophy of ovaries. Furthermore, tracheitis was observed in 24 birds. Bacteriological investigation was done from different organs, and was found in ovaries ( = 20), trachea ( = 17), and cloaca ( = 3). Identification was based on growth morphology, Gram staining, and biochemical properties. Additionally, polymerase chain reaction test using specific primers for the genus identification was carried out. All isolates showed bands of 925 bp specific for expressing the virulent toxin GtxA. Antibiotic resistance testing was performed and revealed that isolates were sensitive to enrofloxacin, florfenicol, and gentamycin but resistant to ampicillin, erythromycin, oxytetracycline, and sulfamethoxazole-trimethoprim. The present study is the first report of in Morocco, demonstrating the need for further epidemiologic investigations as well as in regard to antibiotic resistance development.
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http://dx.doi.org/10.1637/aviandiseases-D-19-00119DOI Listing
December 2019

Efficacy of Massachusetts and 793B Vaccines Against Infectious Bronchitis Moroccan-Italy 02 Virus in Specific-Pathogen-Free Chickens and Commercial Broilers.

Avian Dis 2017 12;61(4):466-471

A Unité de Pathologie Aviaire, Département de Pathologie et Santé Publique Vétérinaire, Institut Agronomique et Vétérinaire Hassan II, BP 6202, Rabat- Instituts, Rabat, Morocco 10000.

The ability of commercial vaccines H120 and 4/91 to protect against Moroccan-Italy 02 infectious bronchitis virus (Mor-It02) was investigated in specific-pathogen-free (SPF) chickens and commercial broiler chickens. Commercial broiler chicks (Experiment 1) were vaccinated at the hatchery with H120 vaccine at Day 1, and challenged at Day 21 with 10 50% egg-infective dose (EID) of Mor-It02. All chicks were observed daily for clinical signs attributable to Mor-It02 infection during the 10 days postchallenge (pc). At 5 and 10 days pc, chicks were humanely sacrificed for necropsy examination, and tissues were collected for histopathology evaluation. To better understand the findings on commercial broilers, day-old SPF chicks were divided into five groups in a second experiment: Group Mass/4-91, vaccinated with H120 and 4/91 respectively at Days 1 and 15 of age; Group Mass/Mass, vaccinated by H120 at Days 1 and 15; Group Mass, vaccinated with H120 at Day 1; Group NV, kept unvaccinated; and Group NC, kept as a negative control (unchallenged). At Day 24 of age, Groups Mass/4-91, Mass/Mass, Mass, and NV were challenged with 10 EID of Mor-It02. In both experiments, blood samples were collected at different periods for serologic analyses. Oropharyngeal swabs were collected for virus detection by reverse-transcription PCR. In Experiments 1 and 2, respiratory signs started as early as 24 hr pc and maximum severity was observed on Days 3 and 4 pc. The viral shedding rate was significantly lower in Group Mass/4-91 compared to other challenged groups. Serologic analysis in both experiments showed that the sera of challenged group exhibited significantly higher antibody titers than sera collected before challenge. Histopathologic investigations in SPF birds showed deciliation and hyperplasia in Group NV and less-pronounced lesions in Groups Mass/Mass and Mass. In commercial broilers vaccinated with H120 alone, hyperplasia and deciliation were observed in 90% of the tracheas. These experiments illustrated that Mor-It02 is pathogenic for chickens and a combination of live H120 and 4/91 vaccines given respectively at Day 1 and Day 15 of age confer a good protection against Mor-It02.
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http://dx.doi.org/10.1637/11686-060817-Reg.1DOI Listing
December 2017

First outbreaks and phylogenetic analyses of avian influenza H9N2 viruses isolated from poultry flocks in Morocco.

Virol J 2016 08 15;13(1):140. Epub 2016 Aug 15.

IHAP, Université de Toulouse, INRA, ENVT, F-31076, Toulouse, France.

Background: H9N2 avian influenza viruses continue to spread in poultry and wild birds worldwide. Morocco just faced its first H9N2 influenza virus outbreaks early 2016 affecting different types of poultry production. After its introduction, the virus spread very rapidly throughout the country.

Methods: Samples were collected from 11 chicken flocks with high morbidity and mortality rates. Four viruses were successfully isolated from broiler chickens and one from broiler breeders and fully sequenced.

Results: Phylogenetic and molecular markers analyses showed the Moroccan viruses belonged to the G1 lineage and likely originated from the Middle East. As known for H9N2 viruses, the Moroccanisolates possess several genetic markers that enhance virulence in poultry and transmission to humans.

Conclusion: The present study demonstrated that under field conditions H9N2 could have a devastating effect on egg production and mortalities and highlighted a lack of surveillance data on the pathogen in the region.
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http://dx.doi.org/10.1186/s12985-016-0596-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4986173PMC
August 2016
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