Muhammad Zubair Shabbir

Effect of supplementation of prebiotic mannan-oligosaccharides and probiotic mixture on growth performance of broilers subjected to chronic heat stress

The present study was aimed at elucidating the effects of supplementing mannan-oligosaccharides (MOS) and probiotic mixture (PM) on growth performance, intestinal histology, and corticosterone concentrations in broilers kept under chronic heat stress (HS). Four hundred fifty 1-d-old chicks were divided into 5 treatment groups and fed a corn-soybean diet ad-libitum. The temperature control (CONT) group was held at the normal ambient temperature. Heat stress broilers were held at 35 ± 2°C from d 1 until the termination of the study at d 42. Heat stress groups consisted of HS-CONT fed the basal diet; HS-MOS fed the basal diet containing 0.5% MOS; HS-PM fed the basal diet containing 0.1% PM; and HS-SYN (synbiotic) fed 0.5% MOS and 0.1% PM in the basal diet. Broilers were examined at d 21 and 42 for BW gain, feed consumption, feed conversion ratio (FCR), serum corticosterone concentrations, and ileal microarchitecture. The results revealed that the CONT group had higher (P < 0.01) feed consumption, BW gain, and lower FCR on d 21 and 42, compared with the HS-CONT group. Among supplemented groups, the HS-MOS had higher (P < 0.05) BW gain and lower FCR compared with the HS-CONT group. On d 21 and 42, the HS-CONT group had higher (P < 0.05) serum corticosterone concentrations compared with the CONT and supplemented groups. The CONT group had higher (P < 0.05) villus height, width, surface area, and crypt depth compared with the HS-CONT group. On d 21, the HS-PM had higher (P < 0.05) villus width and surface area compared with HS-CONT group. On d 42, the HS-SYN had higher (P < 0.05) villus width and crypt depth compared with the HS-CONT group. These results showed that chronic HS reduces broiler production performance, intestinal microarchitecture, and increases adrenal hormone concentrations. Also, supplementation of the MOS prebiotic and the PM can partially lessen these changes.

Biological characterization and phylogenetic analysis of a novel genetic group of Newcastle disease virus isolated from outbreaks in commercial poultry and from backyard poultry flocks in Pakistan.

Newcastle disease (ND) is a contagious viral disease of many avian species particularly domestic poultry, and is responsible for devastating outbreaks in the poultry industries around the globe. In spite of its importance and endemicity in Southern Asia, data on the genetic nature of the viruses and epizootiological information of the disease is scarce. In this study, six isolates from an emerging wave of ND outbreaks in the north of Pakistan and two isolates from healthy poultry flocks were biologically and genetically characterized. Based on pathogenicity indices such as intracerebral pathogenicity index (ICPI), mean death time (MDT) and cleavage motifs in the fusion protein, all these isolates were classified as virulent. Phylogenetic analysis of the fusion (F), hemagglutinin-neuraminidase (HN) and matrix (M) genes indicated the emergence of a novel genetic group within lineage 5, distinct from isolates previously reported in the region. Several mutations in the neutralizing epitopes and functionally important motifs of the F and HN genes pose a need for re-evaluation of the currently used vaccine and vaccination practices. The characteristics of Newcastle disease virus (NDV) as virulent (F protein cleavage site, ICPI and MDT) in apparently healthy backyard poultry (BYP) explain that BYP can play crucial role in the epizootiology and spread of the disease. The present investigation provides essential information on the genetic nature of NDV circulating in Pakistan and its implication on disease diagnosis and control. Furthermore, these investigations emphasize the importance of continuous surveillance of ND in developing countries.

Infectivity and transmissibility of H9N2 avian influenza virus in chickens and wild terrestrial birds

Genetic changes in avian influenza viruses influence their infectivity, virulence and transmission. Recently we identified a novel genotype of H9N2 viruses in widespread circulation in poultry in Pakistan that contained polymerases (PB2, PB1 and PA) and non-structural (NS) gene segments identical to highly pathogenic H7N3 viruses. Here, we investigated the potential of these viruses to cause disease and assessed the transmission capability of the virus within and between poultry and wild terrestrial avian species. Groups of broilers, layers, jungle fowl, quail, sparrows or crows were infected with a representative strain (A/chicken/UDL-01/08) of this H9N2 virus and then mixed with naïve birds of the same breed or species, or different species to examine transmission. With the exception of crows, all directly inoculated and contact birds showed clinical signs, varying in severity with quail showing the most pronounced clinical signs. Virus shedding was detected in all infected birds, with quail showing the greatest levels of virus secretion, but only very low levels of virus were found in directly infected crow samples. Efficient virus intra-species transmission was observed within each group with the exception of crows in which no evidence of transmission was seen. Interspecies transmission was examined between chickens and sparrows and vice versa and efficient transmission was seen in either direction. These results highlight the ease of spread of this group of H9N2 viruses between domesticated poultry and sparrows and show that sparrows need to be considered as a high risk species for transmitting H9N2 viruses between premises.

Epidemiology, phylogeny, and evolution of emerging enteric Picobirnaviruses of animal origin and their relationship to human strains.

Picobirnavirus (PBV) which has been included in the list of viruses causing enteric infection in animals is highly versatile because of its broad host range and genetic diversity. PBVs are among the most recent and emerging small, nonenveloped viruses with a bisegmented double-stranded RNA genome, classified under a new family “Picobirnaviridae.” PBVs have also been detected from respiratory tract of pigs, but needs further close investigation for their inhabitant behavior. Though, accretion of genomic data of PBVs from different mammalian species resolved some of the ambiguity, quite a few questions and hypotheses regarding pathogenesis, persistence location, and evolution of PBVs remain unreciprocated. Evolutionary analysis reveals association of PBVs with partitiviruses especially fungi partitiviruses. Although, PBVs may have an ambiguous clinical implication, they do pose a potential public health concern in humans and control of PBVs mainly relies on nonvaccinal approach. Based upon the published data, from 1988 to date, generated from animal PBVs across the globe, this review provides information and discussion with respect to genetic analysis as well as evolution of PBVs of animal origin in relation to human strains.

Listeriosis in animals, its public health significance (food-borne zoonosis) and advances in diagnosis and control: a comprehensive review

Listeriosis is an infectious and fatal disease of animals, birds, fish, crustaceans and humans. It is an important food-borne zoonosis caused by Listeria monocytogenes, an intracellular pathogen with unique potential to spread from cell to cell, thereby crossing blood–brain, intestinal and placental barriers. The organism possesses a pile of virulence factors that help to infect the host and evade from host immune machinery. Though disease occurrence is sporadic throughout the world, it can result in severe damage during an outbreak. Listeriosis is characterized by septicaemia, encephalitis, meningitis, meningoencephalitis, abortion, stillbirth, perinatal infections and gastroenteritis with the incubation period varying with the form of infection. L. monocytogenes has been isolated worldwide from humans, animals, poultry, environmental sources like soil, river, decaying plants, and food sources like milk, meat and their products, seafood and vegetables. Since appropriate vaccines are not available and infection is mainly transmitted through foods in humans and animals, hygienic practices can prevent its spread. The present review describes etiology, epidemiology, transmission, clinical signs, post-mortem lesions, pathogenesis, public health significance, and advances in diagnosis, vaccines and treatment of this disease. Special attention has been given to novel as well as prospective emerging therapies that include bacteriophage and cytokine therapy, avian egg yolk antibodies and herbal therapy. Various vaccines, including advances in recombinant and DNA vaccines and their modes of eliciting immune response, are also discussed. Due focus has also been given regarding appropriate prevention and control strategies to be adapted for better management of this zoonotic disease.

Genetic diversity of Newcastle disease virus in Pakistan: a countrywide perspective

BackgroundNewcastle disease (ND) is one of the most deadly diseases of poultry around the globe. The disease is endemic in Pakistan and recurrent outbreaks are being reported regularly in wild captive, rural and commercial poultry flocks. Though, efforts have been made to characterize the causative agent in some of parts of the country, the genetic nature of strains circulating throughout Pakistan is currently lacking.Material and methodsTo ascertain the genetics of NDV, 452 blood samples were collected from 113 flocks, originating from all the provinces of Pakistan, showing high mortality (30–80%). The samples represented domesticated poultry (broiler, layer and rural) as well as wild captive birds (pigeons, turkeys, pheasants and peacock). Samples were screened with real-time PCR for both matrix and fusion genes (1792 bp), positive samples were subjected to amplification of full fusion gene and subsequent sequencing and phylogenetic analysis.ResultsThe deduced amino acid sequence of the fusion protein cleavage site indicated the presence of motif (112RK/RQRR↓F117) typical for velogenic strains of NDV. Phylogenetic analysis of hypervariable region of the fusion gene indicated that all the isolates belong to lineage 5 of NDV except isolates collected from Khyber Pakhtunkhwa (KPK) province. A higher resolution of the phylogenetic analysis of lineage 5 showed the distribution of Pakistani NDV strains to 5b. However, the isolates from KPK belonged to lineage 4c; the first report of such lineage from this province.ConclusionsTaken together, data indicated the prevalence of multiple lineages of NDV in different poultry population including wild captive birds. Such understanding is crucial to underpin the nature of circulating strains of NDV, their potential for interspecies transmission and disease diagnosis and control strategies.

Molecular analysis of the caecal and tracheal microbiome of heat-stressed broilers supplemented with prebiotic and probiotic.

The gastrointestinal tract commensal microbiome is important for host nutrition, health and immunity. Little information is available regarding the role of these commensals at other mucosal surfaces in poultry. Tracheal mucosal surfaces offer sites for first-line health and immunity promotion in broilers, especially under stress-related conditions. The present study is aimed at elucidating the effects of feed supplementations with mannanoligosaccharides (MOS) prebiotic and a probiotic mixture (PM) on the caecal and tracheal microbiome of broilers kept under chronic heat stress (HS; 35 ± 2°C). Day-old chickens were randomly divided into five treatment groups: thermoneutral control (TN-CONT), HS-CONT, HS-MOS, HS-PM and HS synbiotic (fed MOS and PM). Caecal digesta and tracheal swabs were collected at day 42 and subjected to DNA extraction, followed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and pyrosequencing. The PCR-DGGE dendrograms revealed significant (49.5% similarity coefficients) differences between caecal and tracheal microbiome. Tracheal microbiome pyrosequencing revealed 9 phyla, 17 classes, 34 orders, 68 families and 125 genera, while 11 phyla, 19 classes, 34 orders, 85 families and 165 genera were identified in caeca. An unweighted UniFrac distance metric revealed a distinct clustering pattern (analysis of similarities, P = 0.007) between caecal and tracheal microbiome. Lactobacillus was the most abundant genus in trachea and caeca and was more abundant in caeca and trachea of HS groups compared with the TN-CONT group. Distinct bacterial clades occupied the caecal and tracheal microbiomes, although some bacterial groups overlapped, demonstrating a core microbiome dominated by Lactobacillus. No positive effects of supplementations were observed on abundance of probiotic bacteria.

Complete Genome Sequence of a Velogenic Neurotropic Avian Paramyxovirus 1 Isolated from Peacocks (Pavo cristatus) in a Wildlife Park in Pakistan

ABSTRACT Avian paramyxovirus serotype 1 (APMV-1) was isolated from an acute and highly contagious outbreak in peacocks (Pavo cristatus) in a wildlife park in Pakistan. A velogenic neurotropic form of APMV-1 caused a 100% case fatality rate and killed 190 peacocks within a week. Biological and serological characterizations showed features of a velogenic strain of APMV-1, and these results were further confirmed by sequence analysis of the cleavage site in the fusion protein. The complete genome of one of the isolates was sequenced, and phylogenetic analysis was conducted. The analysis showed that this isolate belonged to genotype VII, specifically, to subgenotype VIIa, and clustered closely with isolates characterized from Indonesia in the 1990s. Interestingly, the isolate showed significant differences from previously characterized APMV-1 isolates from commercial and rural chickens in Pakistan. The work presented here is the first complete genome sequence of any APMV-1 isolate from wild birds in the region and therefore highlights the need for increased awareness and surveillance in such bird species.

Complete Genome Sequencing of a Velogenic Viscerotropic Avian Paramyxovirus 1 Isolated from Pheasants (Pucrasia macrolopha) in Lahore, Pakistan

ABSTRACT We report the complete genome sequence of avian paramyxovirus 1 (APMV-1) isolated from an acute and highly contagious outbreak in pheasants (Pucrasia macrolopha) in Lahore, Pakistan. Biological and serological characterization showed a velogenic strain of APMV-1, which was further confirmed by the sequence analysis of the cleavage site in the fusion protein. Complete genome sequencing and phylogenetic analysis indicated that this isolate belonged to genotype VII, specifically to subgenotype VIIa, and clustered closely with isolates characterized from Indonesia. Notably, the isolate showed significant differences from previously characterized APMV-1 from Pakistani commercial and rural chicken.

An international collaborative study to determine the prevalence of contagious caprine pleuropneumonia by monoclonal antibody-based cELISA

BackgroundFew serological tests are available for detecting antibodies against Mycoplasma capricolum subsp. capripneumoniae, the causal agent of contagious caprine pleuropneumonia (CCPP). The complement fixation test, the test prescribed for international trade purposes, uses a crude antigen that cross-reacts with all the other mycoplasma species of the “mycoides cluster” frequently infecting goat herds. The lack of a more specific test has been a real obstacle to the evaluation of the prevalence and economic impact of CCPP worldwide. A new competitive ELISA kit for CCPP, based on a previous blocking ELISA, was formatted at CIRAD and used to evaluate the prevalence of CCPP in some regions of Kenya, Ethiopia, Mauritius, Tajikistan and Pakistan in an international collaborative study.ResultsThe strict specificity of the test was confirmed in CCPP-free goat herds exposed to other mycoplasma species of the “mycoides cluster”. Prevalence studies were performed across the enzootic range of the disease in Africa and Asia. Seroprevalence was estimated at 14.6% in the Afar region of Ethiopia, whereas all the herds presented for CCPP vaccination in Kenya tested positive (individual seroprevalence varied from 6 to 90% within each herd). In Mauritius, where CCPP emerged in 2009, nine of 62 herds tested positive. In Central Asia, where the disease was confirmed only recently, no positive animals were detected in the Wakhan District of Afghanistan or across the border in neighboring areas of Tajikistan, whereas seroprevalence varied between 2.7% and 44.2% in the other districts investigated and in northern Pakistan. The test was also used to monitor seroconversion in vaccinated animals.ConclusionsThis newly formatted CCPP cELISA kit has retained the high specificity of the original kit. It can therefore be used to evaluate the prevalence of CCPP in countries or regions without vaccination programs. It could also be used to monitor the efficacy of vaccination campaigns as high-quality vaccines induce high rates of seroconversion.