Assessment and comparison of the pathogenicity of Sheeppox Virus strains isolated in Morocco.

BACKGROUND AND OBJECTIVES: Sheeppox virus causes systemic disease in sheep that is often associated with high morbidity and mortality. Protection against sheep pox is mainly based on medical prophylaxis, vaccination being the only way. In Morocco, and up to now, there is no available information about local challenge strain to use for controlling the efficiency of vaccines produced against sheep pox. Hence, the objective of the present study was to evaluate and compare the pathogenicity of seven Sheeppox virus (SPVs) isolates from 1993-1995 in Morocco. MATERIALS AND METHODS: These seven SPV isolates have undergone various tests to evaluate their pathogenicity: Passages and titration on cell culture, Experimental inoculation on sheep, Virus-neutralization, In vivo titration and viral re-isolation by real-time PCR assay. RESULTS: All infected lambs showed severe clinical signs, while most of them have been reproduced on 5 dpi and persisted until 21 dpi. The lambs infected by Oj1P4, Oj2P4 and BerP5 appeared lethargic, reluctant to move compared to those infected by other isolates. The results also revealed that all isolates were able to induce serological response. Virus isolation from infected organs and blood and amplification of the viral DNA by real-time PCR proved the presence of the virus in tissues and blood of infected lambs. These Moroccan SPVs demonstrated that the three isolates Oj1P4, Oj2P4 and BerP5 have a high pathogenicity; especially the BerP5 isolate which has an important infectious titer. CONCLUSION: These results demonstrate that the Berkane isolate is the most pathogenic of the tested isolates and it can be an excellent challenge strain for the control of the efficiency of vaccines against sheep pox produced in Morocco.

Assessment of pathogenicity and tissue distribution of infectious bronchitis virus strains (Italy 02 genotype) isolated from moroccan broiler chickens.

BACKGROUND: Avian infectious bronchitis (IB) is one of the most important viral diseases of poultry, affecting chickens of all ages and causing major economic losses in poultry flocks. Mass vaccination is conducted in Morocco using a vaccine against Massachusetts, which is the most dominant serotype; however no information about the pathogenesis and tissue distribution of the Moroccan Italy 02 genotype was reported. 40 one-day-old specific pathogen free chickens were divided randomly into four groups. Group1, 2 and 3 were inoculated intra oculo-nasally with 103.5 EID50 of Italy02 viruses, and group 4 was kept as control. Chickens in each group were monitored for 14 days post-infection (pi). RESULTS: Chickens in all infected groups showed severe respiratory signs, which most of them have been reproduced on 2dpi, with varying times of appearance and disappearance. The infected birds appeared lethargic, reluctant to move, with specific respiratory clinical signs and macroscopic lesions. However no nephritis lesions or mortality were recorded in all groups. The specific histological lesions finding in all infected birds, exhibited tracheal lesions with mucosal thickening, hyperplasia of the surface epithelium, mononuclear inflammatory cell infiltrate of lamina propria. Primary and secondary bronchi, epithelial hyperplasia and mononuclear inflammatory cell infiltrate of the lamina propria were also observed. Tracheal lesions developed in all infected birds, confirm the ability of the three tested strains to induce respiratory disease. The results at 14 dpi also revealed that all strains were able to induce serological response. Virus re-isolation from infected organs and amplification of the viral RNA by real-time PCR proved the presence of the virus in lung and trachea of infected chicks. Neither re-isolation nor significant viral RNA detection were detected in the kidney. CONCLUSION: The results demonstrated that the three strains Italy02 genotype emerging in Moroccan poultry farms have a wide distribution for respiratory system, without kidney damage and without causing mortality.

Avian infectious bronchitis virus in Africa: a review.

Infectious bronchitis virus (IBV) is worldwide in distribution, highly infectious, and extremely difficult to control because it has extensive genetic diversity, a short generation time, and a high mutation rate. IBV is a Gammacoronavirus, single-stranded, and positive-sense RNA virus. Avian infectious bronchitis is well studied in European countries with identification of a large number of IBV variants, whereas in African countries epidemiological and scientific data are poor and not updated. However, previous studies reported that an IBV variant continues to appear regularly in Africa, as currently described in Morocco. No cross-protection between IBV strains was reported, some being unique to a particular country, others having a more general distribution. This review aims to provide a general overview on IB disease distribution in African countries and an update on the available studies of IBV variants in each country.

Comparison of SYBR green I real-time RT-PCR with conventional agarose gel-based RT-PCR for the diagnosis of infectious bronchitis virus infection in chickens in Morocco.

BACKGROUND: A rapid, sensitive, and specific molecular method for the diagnosis of infectious bronchitis virus (IBV) infection is important in curbing infectious bronchitis outbreaks in Morocco and other countries. METHODS: In this study, an easy-to-perform SYBR green I real-time reverse transcriptase polymerase chain reaction (RT-PCR) targeting the nucleocapsid gene of IBV was developed and compared with conventional agarose gel-based RT-PCR for the detection of IBV infection. RESULTS: We found that the SYBR green I real-time RT-PCR was at least 10 times more sensitive than the agarose gel electrophoresis detection method. The assay exhibited high specificity for IBV infection. All negative controls, such as Newcastle disease virus, infectious bursal disease virus, and avian influenza virus, were not detected. CONCLUSION: The SYBR green I real-time RT-PCR test described herein can be used to rapidly distinguish IBV from other respiratory pathogens, which is important for diagnosis and control of infectious bronchitis outbreaks in Morocco. The test is a valuable and useful method as a routine assay for diagnosis of clinical IBV infection in commercial chickens.

Current situation, genetic relationship and control measures of infectious bronchitis virus variants circulating in African regions.

Infectious bronchitis virus (IBV) is a major viral pathogen of commercial poultry, affecting chickens of all ages and causing major economic losses in poultry industry worldwide. Frequent points of mutations and recombination events in the S1 gene region, result in the emergence of new IBVs variants circulating in the form of several serotypes/genotypes that can be partially or poorly neutralized by current vaccines. IBV is well studied worldwide, nevertheless in African countries epidemiological and scientific data are poor and not updated. This review aims to give a current overview of IBV situation, to establish evolutionary relationship between the African variants and to list some of the potential measures to control IBV in Africa. Three S1 gene hypervariable regions were studied and compared to the reference genotypes/serotypes that found emerging in African regions. This comparison was based on phylogenetic trees, nucleotide and amino-acid sequence analysis. It clearly appears that IBV variants reported in Africa, display a low genetic relationship between them and with the majority of the reference strains emerging in neighboring countries, except the case of variants from Libya and Egypt that show a high relatedness. Also the Massachusetts serotypes were the most prevalent co-circulating with both serotypes, Italy02 type in Morocco and Qx-like genotype in South part of the African continent. In order to control the IBV variants in African regions, an efficient vaccination strategy program should be implemented.

Prevalence and molecular characterization of avian infectious bronchitis virus in poultry flocks in Morocco from 2010 to 2014 and first detection of Italy 02 in Africa.

The aim of this study was to investigate the prevalence and diversity of infectious bronchitis virus (IBV) genotypes in poultry flocks in 16 areas of Morocco between 2010 and 2014. A total of 360 chicken flocks suspected of being infected by IBV were screened for the IBV N gene using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Flocks were classified into four groups according to their IBV vaccination programme. Group 1 contained unvaccinated birds. Group 2 received a single application of live H120 vaccine. Groups 3 and 4 birds received one or two booster vaccination(s), respectively, mostly using the H120 vaccine. The real-time RT-PCR results showed that 51.7% of the flocks were positive for the IBV genome with geographical disparities. Molecular characterization of IBV was performed on 50 RT-PCR positive samples by partially sequencing the S1 gene, including the hypervariable regions (nucleotides 705-1097). Two predominant genotypes were detected, with the Massachusetts type dominating (66%), among which 25% of the samples were identical to the H120 vaccine. The second most common genotype (present in 32% of the flocks) was surprisingly Italy 02, revealing the first detection of this genotype in Morocco and also in Africa. 793B, the predominant genotype in the late 1990s in Morocco, was only detected on one occasion and was identical to the 4/91 vaccine strain. This study highlights the high prevalence of IBV in poultry farms in Morocco and confirms its continuous dynamic changes and evolution.