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.

The isolation and characterisation of six avian infectious bronchitis viruses isolated in Morocco

The first isolation and characterisation of infectious bronchitis (IB) viruses from poultry flocks in Morocco are reported. Five isolates designated D, E, F, H and M were related serologically to the Massachusetts serotype, while the sixth, isolate G, was found to be different from any previously reported serotype of IB virus. Neutralising antibodies to isolate G have been detected in sera collected from commercial flocks in Britain, although the virus has not been isolated. While all six isolates caused respiratory disease typical of IB in experimentally infected 3-week-old specified pathogen-free (SPF) chickens, isolate G was unusual in that it could be isolated from several parts of the alimentary tract for up to 21 days post inoculation, and from the duodenum up to 28 days. H120 vaccines protected chicks challenged with isolates E and F but not isolate G.