Continuous circulation and mutation at the hypervariable region of the VP2 gene of very virulent infectious bursal disease virus in Nigeria

Infectious bursal disease (IBD) is a highly contagious viral disease of poultry with huge economic consequences. First reported in Nigeria in 1973, the disease has since become endemic across the country. Inspite of routine vaccine administration, outbreaks are frequently reported in vaccinated flocks which questions the effectiveness of the vaccine to confer adequate protection against the circulating strains of the virus. In this study, suspected IBD outbreaks from 9 poultry farms spanning 2015 – 2016 were investigated. The hypervariable region (HVR) of the VP2 gene of infectious bursal disease virus (IBDV) from these outbreaks was sequenced. Based on the phylogenetic tree and deduced amino acid sequences, the viruses clustered with African very virulent (vv) types (VV2-1) with markers typical for vvIBDV at positions 222A, 242I, 256I, 294I and 299S. Also, unique substitutions were identified at the hydrophilic peak A (215Q→P) and minor peak 2 (280N→Y) in addition to that previously unreported at position 308I→L. These results demonstrate continuous circulation and mutations at the HVR of the VP2 which underscores the need for constant monitoring of IBDV in Nigerian poultry. Further study is required to establish the biological function(s) of these mutations on the pathogenicity and antigenicity of the virus.Keywords: very virulent infectious bursal disease virus, VP2 gene, mutation, poultry, Nigeri

Occurrence and molecular detection of avian coronavirus in selected live bird markets, northwestern, Nigeria

Infectious bronchitis (IB) is one of the most common highly infectious viral respiratory diseases of poultry having wide geographical  distribution. Yet, little is known about the infection in the northwestern states of Nigeria. In this study, a total of 263 pooled cloacal and tracheal swab samples were collected from apparently healthy avian species (duck, dove, geese, guinea fowl, local chicken, ostrich, parrot, pigeon, peacock, and turkey). The samples were from nine live bird markets in three states (Kaduna, Kano and Jigawa) of northwestern,  Nigeria collected from September through November 2017. Total RNAs were extracted directly from the swab samples and screened for infectious bronchitis virus (IBV) using real-time reverse transcription-polymerase chain reaction. An overall prevalence of 38.0% (100/263)was recorded. IB was detected in 70 % (7/10) of the avian species with prevalence of 100 % in dove, local chicken 45.9 %, duck 42.3 %, geese 26.6 %, pigeon 23.5 %, turkey 20.0 % and guinea fowl 6.2 %. Conversely, no detection was made from ostrich, parrot, and peacock.  Widespread distribution of IBV was observed and evidence of subclinical infection in seven out of ten (70 %) of the avian species sampled. These avian species harbouring IBV may act as reservoirs with an influence on the ecology and epidemiology of the disease. Continuous surveillance and characterization of the different serotypes in avian species are recommended to inform the adoption of suitable  vaccination strategy and control measures for the disease in Nigeria. Keywords: Infectious bronchitis virus, Live bird markets (LBMs), Molecular detection, Nigeria, Poultr

Sero-prevalence and serotypes of infectious bronchitis virus in free-range chicken in Plateau state, Nigeria

Globally, infectious bronchitis (IB) is an important respiratory viral disease responsible for enormous economic losses to poultry farmers.  In Nigeria, limited reports on the prevalence and serotypes of the IB virus are available. Here, we investigated the prevalence and serotypes of infectious bronchitis virus (IBV) in chicken in Plateau State. A descriptive cross-sectional study was carried out involving 440 apparently healthy free-range local chickens sampled from eleven villages in four Local Government Areas (LGA) of Plateau State. Sera collected from the birds were screened for the presence of four IBV serotypes namely; Massachusetts (Mass), Arkansas (Ark), Connecticut (Con) and Delaware (De-072) using haemagglutinationinhibition (HI) test. In all, a prevalence of 82.95% (n = 365) was recorded. At LGAlevel, prevalence of 79.50%, 47.37%, 95.45% and 100% were recorded in Kanam, Mangu, Qua’an pan and Bassa LGAs, respectively. Based on serotype prevalence, Mass had 89.30% (n = 326); Ark 79.70% (n = 291); Con 88.20% (n = 322) while De-072 was 42.70% (n = 156). There were statistically significant associations between dominant serotype and the LGAs (p≤0.001). This study shows high prevalence of IBwith at least four strains of IBV present in free-range chicken flocks in Plateau State requiring attention for control measures. Keywords: Free-range chicken; Infectious bronchitis virus; Plateau state, Serosurvey, Serotyp

Fowlpox virus from backyard poultry in Plateau State Nigeria: isolation and phylogeny of the P4b gene compared to a vaccine strain

Fowlpox is a viral infection that cause nodular and diphtheritic lesions on the skin and mucous membrane of the digestive and respiratory tracts of birds. It is a disease of economic importance in domestic and wild birds especially in tropical and subtropical countries. Despite its endemicity, there is limited literature on the genetic diversity of field virus circulating in Nigeria. In this study, cutaneous tissue samples were aseptically collected from suspected poultry flocks through passive surveillance conducted in Plateau state Nigeria from 2009 to 2013. Fowlpox virus was isolated in chorion allantoic membrane of embryonated chicken eggs and identified with Agar Gel Immuno Diffusion test using homologous reference antigen and antisera. Genomic DNA amplification and cycle sequencing of the P4b gene locus of seven selected field isolates along with a local vaccine strain was done and analysed alongside published sequences of FPV P4b gene using MEGA 5 software. Nucleotide analysis of our isolates and a vaccine strain showed 100% similarity and also shared 72 – 100% homology with selected sequences from the GenBank while clustering on the phylogenetic tree in clade A, subclade A1. This study represents the first available fowl poxvirus sequences (KP987207-KP987214) from the West and Central Africa regions in the GenBank. Full genome sequences and comparative molecular analysis of circulating field and vaccine strain is critical for the design and implementation of target oriented control programme.Keywords: Fowlpox, Isolation, Nigeria, Phylogeny, Viru

Epidemiology and clinicopathological manifestation of resurgent highly Pathogenic Avian Influenza (H5N1) virus in Nigeria, 2015

In January, 2015 the National Veterinary Research Institute, Vom, Nigeria received some chicken carcasses from the Kano state Ministry of Agriculture. The carcasses were from a backyard-commercial poultry farm and a live bird market (LBM) in Kauna and Sabon gari, Kano state, northwestern Nigeria respectively. The farm kept  different types of chickens of various ages and stages and was experiencing high mortality of 350 birds daily with eventual 100% mortality observed in the older birds (54weeks). In a concurrent incidence, reports were received of unusual high mortality of birds brought from the northern part of the country at two LBMs in  Onipanu and Mushin, Lagos state, southwestern Nigeria. A total of 8 chicken  carcasses from the Kano suspicion were subjected to postmortem examination and testing. One broiler-chicken (4weeks old), 4 layer-chicken (22 weeks old) and 3 indigenous bred-chickens (from LBM) showed severe pathological lesions  consistent with highly pathogenic avian influenza (HPAI). Moribund birds from the Lagos suspicion had cyanotic comb and wattles, torticollis and paralysis of the limbs. Parenchymatous organs, nasal and trachea swabs were collected from the dead and moribund birds respectively. The specimens were analyzed by RT-PCR and virus isolation in embryonating chicken eggs. All samples were found to be positive for HPAI (H5N1) subtype. This marks the re-introduction of HPAI (H5N1) subtype into Nigeria for a second time in the space of 9-years. So far, over 542 cases (January to December, 2015) have been confirmed positive for HPAI (H5N1) in 20 states of the country. Possible circumstances surrounding the resurgent and spread are discussed herein.Key words: Epidemiology, Resurgent HPAI H5N1, Pathology, Nigeria