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1.
Vet Microbiol ; 263: 109251, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34656859

RESUMO

Infection dynamics data for influenza A virus in a species is important for understanding host-pathogen interactions and developing effective control strategies. Seven-week-old ostriches challenged with H7N1 low pathogenic viruses (LPAIV) or clade 2.3.4.4B H5N8 high pathogenic viruses (HPAIV) were co- housed with non-challenged contacts. Clinical signs, virus shed in the trachea, cloaca, and feather pulp, and antibody responses were quantified over 14 days. H7N1 LPAIV-infected ostriches remained generally healthy with some showing signs of mild conjunctivitis and rhinitis attributed to Mycoplasma co-infection. Mean tracheal virus shedding titres in contact birds peaked 3 days (106.2 EID50 equivalents / ml) and 9 days (105.28 EID50 equivalents / ml) after introduction, lasting for at least 13 days post infection. Cloacal shedding was substantially lower and ceased within 10 days of onset, and low virus levels were detected in wing feather pulp up until day 14. H5N8 HPAIV -infected ostriches showed various degrees of morbidity, with 2/3 mortalities in the in-contact group. Mean tracheal shedding in contact birds peaked 8 days after introduction (106.32 EID50 equivalents/ ml) and lasted beyond 14 days in survivors. Cloacal shedding and virus in feather pulp was generally higher and more consistently positive compared to H7N1 LPAIV, and was also detectable at least until 14 days post infection in survivors. Antibodies against H5N8 HPAIV and H7N1 LPAIV only appeared after day 7 post exposure, with higher titres induced by the HPAIV compared to the LPAIV, and neuraminidase treatment was essential to remove non-specific inhibitors from the H5N8-positive antisera.

2.
Prev Vet Med ; 196: 105474, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34564052

RESUMO

High pathogenicity avian influenza (HPAI) has become a major focus point worldwide due to its zoonotic potential and economic effects resulting from trade restrictions and high mortality rates in poultry. Key ostrich producing provinces of South Africa have experienced three H5N2 HPAI outbreaks (2004, 2006 and 2011) and one H5N8 HPAI (2017) outbreak over the past two decades. The Klein Karoo region in the Western Cape Province, a province with a largely Mediterranean climate, is the predominant ostrich producing region in the country. Understanding the epidemiology of HPAI in ostrich producing areas is an essential first step in developing effective and efficient control measures. This study investigated the spatiotemporal patterns associated with the 2011 (H5N2) and 2017 (H5N8) HPAI outbreaks in the key ostrich producing areas of South Africa. Six hundred and nine and 340 active ostrich farms/holdings were subjected to surveillance during 2011 and 2017 respectively, with over 70 % of these farms located within five local municipalities of the study area. Forty-two and fifty-one farms were affected in the 2011 and 2017 outbreaks respectively. Both HPAI outbreaks occurred predominantly in areas of high ostrich farm density. However, the temporal occurrence, spatial and directional distributions of the outbreaks were different. The 2011 outbreak occurred earlier in the South African autumn months with a predominantly contiguous and stationary distribution, whilst the 2017 outbreak onset was during the winter with a more expansive multidirectional spatial distribution. Results suggest potential dissimilarities in the important risk factors for introduction and possible mode of spread. The 2011 outbreak pattern resembled an outbreak characterised by point introductions with the risk of introduction possibly being linked to high ostrich farm density and common management and husbandry practices in the ostrich industry. In contrast, the 2017 outbreak appeared to have a more propagating mode of transmission. The findings highlight epidemiological features of HPAI outbreak occurrence within ostrich populations that could be used to inform surveillance and control measures including targeted surveillance within high-risk spatial clusters. The study emphasizes the importance of both; implementation of a multi-pronged approach to HPAI control and the need for constant evaluation of the interaction of the host, environment and agent with each outbreak, in order to strengthen disease control.


Assuntos
Vírus da Influenza A Subtipo H5N2 , Influenza Aviária , Doenças das Aves Domésticas , Struthioniformes , Animais , Surtos de Doenças/veterinária , Vírus da Influenza A Subtipo H5N2/patogenicidade , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , África do Sul/epidemiologia , Análise Espaço-Temporal , Struthioniformes/virologia , Virulência
3.
J Vet Diagn Invest ; 33(6): 1089-1095, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34293996

RESUMO

Avian influenza surveillance is a requirement for commercial trade in ostrich products, but influenza A viruses (IAVs) have proven difficult to isolate from ostrich tracheal swabs that test positive using molecular methods. We hypothesized that microbes unique to the ostrich trachea propagate in the transport medium after sampling and affect viral viability. We cultured tracheal swabs from 50 ostriches on 4 farms in South Africa, and recovered and identified 13 bacterial, 1 yeast, and 2 fungal species. Dietzia sp. had not been identified previously in the oropharyngeal tract of a bird, to our knowledge. The bacteria were tested for antimicrobial susceptibility, and most aerobic species, except for Streptococcus sp. and Pseudomonas sp., were sensitive to enrofloxacin; all were susceptible to sulfonamide. Virus inhibition experiments determined that ostrich-source Streptococcus sp., Pantoea sp., and Citrobacter freundii produced extracellular metabolites that caused a substantial reduction in the IAV titers of 99.9%. Streptomyces, Corynebacterium, Staphylococcus, Arthrobacter gandavensis, Pseudomonas putida, and Acinetobacter spp. similarly reduced the viability of IAV from 77.6% to 24.1%. Dietzia appeared to have no effect, but Rothia dentocariosa, Rhodotorula spp., and Clostridium spp. slightly increased the viability of IAV by 25.9, 34.9, and 58.5%, respectively.


Assuntos
Arthrobacter , Vírus da Influenza A , Influenza Aviária , Struthioniformes , Animais , Fazendas , Micrococcaceae
4.
PLoS One ; 15(10): e0240290, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33031421

RESUMO

Highly pathogenic (HPAI) strains emerge from their low pathogenic (LPAI) precursors and cause severe disease in poultry with enormous economic losses, and zoonotic potential. Understanding the mechanisms involved in HPAI emergence is thus an important goal for risk assessments. In this study ostrich-origin H5N2 and H7N1 LPAI progenitor viruses were serially passaged seventeen times in 14-day old embryonated chicken eggs and Ion Torrent ultra-deep sequencing was used to monitor the incremental changes in the consensus genome sequences. Both virus strains increased in virulence with successive passages, but the H7N1 virus attained a virulent phenotype sooner. Mutations V63M, E228V and D272G in the HA protein, Q357K in the nucleoprotein (NP) and H155P in the neuraminidase protein correlated with the increased pathogenicity of the H5N2 virus; whereas R584H and L589I substitutions in the polymerase B2 protein, A146T and Q220E in HA plus D231N in the matrix 1 protein correlated with increased pathogenicity of the H7N1 virus in embryos. Enzymatic cleavage of HA protein is the critical virulence determinant, and HA cleavage site motifs containing multibasic amino acids were detected at the sub-consensus level. The motifs PQERRR/GLF and PQRERR/GLF were first detected in passages 11 and 15 respectively of the H5N2 virus, and in the H7N1 virus the motifs PELPKGKK/GLF and PELPKRR/GLF were detected as early as passage 7. Most significantly, a 13 nucleotide insert of unknown origin was identified at passage 6 of the H5N2 virus, and at passage 17 a 42 nucleotide insert derived from the influenza NP gene was identified. This is the first report of non-homologous recombination at the HA cleavage site in an H5 subtype virus. This study provides insights into how HPAI viruses emerge from low pathogenic precursors and demonstrated the pathogenic potential of H5N2 and H7N1 strains that have not yet been implicated in HPAI outbreaks.


Assuntos
Vírus da Influenza A Subtipo H5N2/isolamento & purificação , Vírus da Influenza A Subtipo H7N1/isolamento & purificação , Animais , Embrião de Galinha , Sequência Consenso , Sequenciamento de Nucleotídeos em Larga Escala , Recombinação Homóloga , Vírus da Influenza A Subtipo H5N2/genética , Vírus da Influenza A Subtipo H5N2/fisiologia , Vírus da Influenza A Subtipo H7N1/genética , Vírus da Influenza A Subtipo H7N1/fisiologia , Inoculações Seriadas
5.
Plant Biotechnol J ; 18(2): 502-512, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31350931

RESUMO

The efficacy, safety, speed, scalability and cost-effectiveness of producing hemagglutinin-based virus-like particle (VLP) vaccines in plants are well-established for human influenza, but untested for the massive poultry influenza vaccine market that remains dominated by traditional egg-grown oil-emulsion whole inactivated virus vaccines. For optimal efficacy, a vaccine should be closely antigenically matched to the field strain, requiring that influenza A vaccines be updated regularly. In this study, an H6 subtype VLP transiently expressed in Nicotiana benthamiana was formulated into a vaccine and evaluated for efficacy in chickens against challenge with a heterologous H6N2 virus. A single dose of the plant-produced H6 VLP vaccine elicited an immune response comparable to two doses of a commercial inactivated H6N2 vaccine, with mean hemagglutination inhibition titres of 9.3 log2 and 8.8 log2 , respectively. Compared to the non-vaccinated control, the H6 VLP vaccine significantly reduced the proportion of shedders and the magnitude of viral shedding by >100-fold in the oropharynx and >6-fold in the cloaca, and shortened oropharyngeal viral shedding by at least a week. Despite its potency, the cost of the antigenic mismatch between the inactivated H6N2 vaccine and challenge strain was evident not only in this vaccine's failure to reduce viral shedding compared to the non-vaccinated group, but its apparent exacerbation of oropharyngeal viral shedding until 21 days post-challenge. We estimate that a kilogram of plant leaf material can produce H6 VLP vaccines sufficient for between 5000 and 30 000 chickens, depending on the effective dose and whether one or two immunizations are administered.


Assuntos
Anticorpos Antivirais , Vírus da Influenza A , Vacinas contra Influenza , Doenças das Aves Domésticas , Vacinas de Partículas Semelhantes a Vírus , Animais , Anticorpos Antivirais/sangue , Galinhas , Vírus da Influenza A/imunologia , Vacinas contra Influenza/imunologia , Doenças das Aves Domésticas/prevenção & controle , Tabaco/genética , Tabaco/metabolismo , Vacinas de Partículas Semelhantes a Vírus/imunologia , Vacinas de Partículas Semelhantes a Vírus/normas , Eliminação de Partículas Virais
6.
Transbound Emerg Dis ; 67(3): 1371-1381, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31833671

RESUMO

Asian-origin H5N8 highly pathogenic avian influenza (HPAI) viruses of the H5 Goose/Guangdong/96 lineage, clade 2.3.4.4 group B, reached South Africa by June 2017. By the end of that year, 5.4 million layers and broiler chickens died or were culled, with total losses in the poultry industry estimated at US$ 140 million, and thousands of exotic birds in zoological collections, endangered endemic species and backyard poultry and pet birds also perished. The 2017 H5N8 HPAI outbreaks were characterized by two distinct spatial clusters, each associated with specific reassortant viral genotypes. Genotypes 1, 2, 3 and 5 were restricted to the northern regions, spanning the provinces of Limpopo, Gauteng, North West, Mpumalanga, KwaZulu-Natal and Free State. The second, much larger cluster of outbreaks was in the south, in the Western and Eastern Cape provinces, wherein 2017 and 2018 outbreaks were caused solely by genotype 4. The last confirmed case of H5N8 HPAI in the northern region in 2017 was in early October, and the viruses seemed to disappear over the summer. However, starting in mid-February 2018, H5N8 HPAI outbreaks resurged in the north. Viruses from two of the eight outbreaks were sequenced, one from an outbreak in quails (Coturnix japonica) in the North West Province, and another from commercial pullets in the Gauteng province. Phylogenetic analysis identified the viruses as a distinct sixth genotype that was most likely a new introduction to South Africa in early 2018.


Assuntos
Surtos de Doenças/veterinária , Genótipo , Vírus da Influenza A Subtipo H5N8/genética , Influenza Aviária/epidemiologia , Animais , Aves , Vírus da Influenza A Subtipo H5N8/isolamento & purificação , Filogenia , Vírus Reordenados , África do Sul/epidemiologia
7.
BMC Vet Res ; 15(1): 455, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852473

RESUMO

BACKGROUND: The threat of poultry-origin H6 avian influenza viruses to human health emphasizes the importance of monitoring their evolution. South Africa's H6N2 epidemic in chickens began in 2001 and two co-circulating antigenic sub-lineages of H6N2 could be distinguished from the outset. The true incidence and prevalence of H6N2 in the country has been difficult to determine, partly due to the continued use of an inactivated whole virus H6N2 vaccine and the inability to distinguish vaccinated from non-vaccinated birds on serology tests. In the present study, the complete genomes of 12 H6N2 viruses isolated from various farming systems between September 2015 and February 2019 in three major chicken-producing regions were analysed and a serological experiment was used to demonstrate the effects of antigenic mismatch in diagnostic tests. RESULTS: Genetic drift in H6N2 continued and antigenic diversity in sub-lineage I is increasing; no sub-lineage II viruses were detected. Reassortment patterns indicated epidemiological connections between provinces as well as different farming systems, but there was no reassortment with wild bird or ostrich influenza viruses. The sequence mismatch between the official antigens used for routine hemagglutination inhibition (HI) testing and circulating field strains has increased steadily, and we demonstrated that H6N2 field infections are likely to be missed. More concerning, sub-lineage I H6N2 viruses acquired three of the nine HA mutations associated with human receptor-binding preference (A13S, V187D and A193N) since 2002. Most sub-lineage I viruses isolated since 2015 acquired the K702R mutation in PB2 associated with the ability to infect humans, whereas prior to 2015 most viruses in sub-lineages I and II contained the avian lysine marker. All strains had an unusual HA0 motif of PQVETRGIF or PQVGTRGIF. CONCLUSIONS: The H6N2 viruses in South African chickens are mutating and reassorting amongst themselves but have remained a genetically pure lineage since they emerged more than 18 years ago. Greater efforts must be made by government and industry in the continuous isolation and characterization of field strains for use as HI antigens, new vaccine seed strains and to monitor the zoonotic threat of H6N2 viruses.


Assuntos
Galinhas/virologia , Vírus da Influenza A/genética , Influenza Aviária/virologia , Animais , Deriva Genética , Genoma Viral , Testes de Inibição da Hemaglutinação/veterinária , Vírus da Influenza A/classificação , Vírus Reordenados/genética , Testes Sorológicos , África do Sul/epidemiologia , Vacinas de Produtos Inativados
8.
Nat Commun ; 10(1): 5310, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31757953

RESUMO

The role of Africa in the dynamics of the global spread of a zoonotic and economically-important virus, such as the highly pathogenic avian influenza (HPAI) H5Nx of the Gs/GD lineage, remains unexplored. Here we characterise the spatiotemporal patterns of virus diffusion during three HPAI H5Nx intercontinental epidemic waves and demonstrate that Africa mainly acted as an ecological sink of the HPAI H5Nx viruses. A joint analysis of host dynamics and continuous spatial diffusion indicates that poultry trade as well as wild bird migrations have contributed to the virus spreading into Africa, with West Africa acting as a crucial hotspot for virus introduction and dissemination into the continent. We demonstrate varying paths of avian influenza incursions into Africa as well as virus spread within Africa over time, which reveal that virus expansion is a complex phenomenon, shaped by an intricate interplay between avian host ecology, virus characteristics and environmental variables.


Assuntos
Influenza Aviária/transmissão , Influenza Humana/transmissão , Doenças das Aves Domésticas/transmissão , África , África Ocidental , Animais , Humanos , Virus da Influenza A Subtipo H5N1/genética , Vírus da Influenza A Subtipo H5N8/genética , Vírus da Influenza A/genética , Influenza Aviária/economia , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Influenza Humana/economia , Influenza Humana/epidemiologia , Influenza Humana/virologia , Filogenia , Aves Domésticas , Doenças das Aves Domésticas/economia , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/virologia
9.
Microbiol Resour Announc ; 8(30)2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31346015

RESUMO

A hemagglutinating virus isolated during routine surveillance in ostriches was sequenced, identified as avian orthoavulavirus 1 (AOaV-1), and classified as a class I genotype 1.2 virus, with recent common ancestors in Eurasian wild ducks. This is the first class I AOaV-1 isolate from Africa and the first identified in ostriches.

10.
Infect Genet Evol ; 74: 103917, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31200111

RESUMO

Several Avian paramyxoviruses 1 (synonymous with Newcastle disease virus or NDV, used hereafter) classification systems have been proposed for strain identification and differentiation. These systems pioneered classification efforts; however, they were based on different approaches and lacked objective criteria for the differentiation of isolates. These differences have created discrepancies among systems, rendering discussions and comparisons across studies difficult. Although a system that used objective classification criteria was proposed by Diel and co-workers in 2012, the ample worldwide circulation and constant evolution of NDV, and utilization of only some of the criteria, led to identical naming and/or incorrect assigning of new sub/genotypes. To address these issues, an international consortium of experts was convened to undertake in-depth analyses of NDV genetic diversity. This consortium generated curated, up-to-date, complete fusion gene class I and class II datasets of all known NDV for public use, performed comprehensive phylogenetic neighbor-Joining, maximum-likelihood, Bayesian and nucleotide distance analyses, and compared these inference methods. An updated NDV classification and nomenclature system that incorporates phylogenetic topology, genetic distances, branch support, and epidemiological independence was developed. This new consensus system maintains two NDV classes and existing genotypes, identifies three new class II genotypes, and reduces the number of sub-genotypes. In order to track the ancestry of viruses, a dichotomous naming system for designating sub-genotypes was introduced. In addition, a pilot dataset and sub-trees rooting guidelines for rapid preliminary genotype identification of new isolates are provided. Guidelines for sequence dataset curation and phylogenetic inference, and a detailed comparison between the updated and previous systems are included. To increase the speed of phylogenetic inference and ensure consistency between laboratories, detailed guidelines for the use of a supercomputer are also provided. The proposed unified classification system will facilitate future studies of NDV evolution and epidemiology, and comparison of results obtained across the world.


Assuntos
Vírus da Doença de Newcastle/classificação , RNA Viral/genética , Análise de Sequência de RNA/métodos , Teorema de Bayes , Consenso , Curadoria de Dados , Bases de Dados Genéticas , Genótipo , Guias como Assunto , Cooperação Internacional , Funções Verossimilhança , Vírus da Doença de Newcastle/genética , Filogenia
11.
Foodborne Pathog Dis ; 16(9): 652-660, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31099598

RESUMO

Prolonged and widespread in-feed use of antimicrobials as either growth promoters or to treat bacterial infections in commercial poultry production contributed to the emergence of resistant bacterial strains globally. A total of 3544 avian pathogenic Escherichia coli strains isolated from commercial broilers in South Africa between 2009 and 2015 were tested for susceptibility against eight classes of antimicrobials. Time series analyses were conducted to assess seasonal and general trends in antibiotic resistance. Seasonal trends were seen in the tetracyclines, with peaks of resistance in the winter months when respiratory diseases are at their worst. Resistance to quinolones peaked in 2012 after which there was an overall decreasing trend in resistance. Colistin resistance increased gradually from 2009 with a drastic rise to 12.08% in 2015, but its use in feed was stopped in 2016. Florfenicol also showed a sharp increase in resistance from 2.36% in 2009 to 6.63% in 2015. Resistance to trimethoprim-sulphadiazine decreased sharply by the end of 2015, as did spectinomycin and fosfomycin and amoxicillin. The overall prevalence of multidrug resistance (MDR) was 80.6 (95% confidence interval, 0.743-0.819), but the years 2013, 2014, and 2015 showed a significantly lower level of MDR compared with 2009. This study is the first detailed analysis of antimicrobial resistance in poultry production in the country, and constant monitoring of resistance data should be continued to aid in the judicious use of antimicrobial compounds.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Infecções por Escherichia coli/veterinária , Escherichia coli/isolamento & purificação , Doenças das Aves Domésticas/epidemiologia , Aves Domésticas , Animais , Escherichia coli/efeitos dos fármacos , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , Doenças das Aves Domésticas/microbiologia , Prevalência , África do Sul/epidemiologia
12.
Arch Virol ; 164(8): 2031-2047, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31123963

RESUMO

Newcastle disease virus (NDV) has a wide avian host range and a high degree of genetic variability, and virulent strains cause Newcastle disease (ND), a worldwide concern for poultry health. Although NDV has been studied in Nigeria, genetic information about the viruses involved in the endemicity of the disease and the transmission that likely occurs at the poultry-wildlife interface is still largely incomplete. Next-generation and Sanger sequencing was performed to provide complete (n = 73) and partial genomic sequence data (n = 38) for NDV isolates collected from domestic and wild birds in Nigeria during 2002-2015, including the first complete genome sequences of genotype IV and subgenotype VIh from the African continent. Phylogenetic analysis revealed that viruses of seven different genotypes circulated in that period, demonstrating high genetic diversity of NDV for a single country. In addition, a high degree of similarity between NDV isolates from domestic and wild birds was observed, suggesting that spillovers had occurred, including to three species that had not previously been shown to be susceptible to NDV infection. Furthermore, the first spillover of a mesogenic Komarov vaccine virus is documented, suggesting a previous spillover and evolution of this virus. The similarities between viruses from poultry and multiple bird species and the lack of evidence for host adaptation in codon usage suggest that transmission of NDV between poultry and non-poultry birds occurred recently. This is especially significant when considering that some viruses were isolated from species of conservation concern. The high diversity of NDV observed in both domestic and wild birds in Nigeria emphasizes the need for active surveillance and epidemiology of NDV in all bird species.


Assuntos
Animais Selvagens/virologia , Aves/virologia , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Animais , Variação Genética/genética , Genômica/métodos , Genótipo , Nigéria , Filogenia , Aves Domésticas/virologia , Sequenciamento Completo do Genoma/métodos
13.
Vet Microbiol ; 227: 127-132, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30473343

RESUMO

Reported mass mortalities in wild pigeons and doves during the 2017/2018 Clade 2.3.4.4 HPAI H5N8 outbreaks in South Africa necessitated an investigation of healthy racing pigeons for their susceptibility and ability to transmit a Clade 2.3.4.4 sub-group B virus of South African origin. Pigeons challenged with medium (104.5 EID50) and high doses (106 EID50) but not a low dose (103 EID50) of virus, shed virus in low levels of <103 EID50/ml from the oropharynx and cloaca for up to eight days, with peak shedding around 4 days post challenge. Challenged pigeons were able to transmit the virus to contact pigeons, but not contact chickens. Neither pigeons nor chickens presented clinical disease, and only two pigeons in the group that received the high challenge dose developed influenza A-virus specific antibodies. The levels of virus shed by the racing pigeons were well below the published bird infectious dose 50 values for most poultry, especially chickens, therefore the risk that racing pigeons could act as propagators and disseminators through excretion of Clade 2.3.4.4 HPAI H5N8 strains remains negligible.


Assuntos
Doenças das Aves/virologia , Columbidae/virologia , Surtos de Doenças/veterinária , Vírus da Influenza A Subtipo H5N8/patogenicidade , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Anticorpos Antivirais , Doenças das Aves/mortalidade , Doenças das Aves/transmissão , Galinhas , Surtos de Doenças/estatística & dados numéricos , Vírus da Influenza A Subtipo H5N8/classificação , Vírus da Influenza A Subtipo H5N8/genética , Vírus da Influenza A Subtipo H5N8/isolamento & purificação , Influenza Aviária/mortalidade , Influenza Aviária/transmissão , Doenças das Aves Domésticas/mortalidade , Doenças das Aves Domésticas/patologia , África do Sul , Eliminação de Partículas Virais
14.
Appl Environ Microbiol ; 84(21)2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30171000

RESUMO

One hundred seventy-eight mycoplasma strains isolated from South African poultry flocks between 2003 and 2015 were identified by full-genome sequencing and phylogenetic analysis of the 16S rRNA gene and were classified as follows: Mycoplasma gallisepticum (25%), M. gallinarum (25%), M. gallinaceum, (23%), M. pullorum (14%), M. synoviae (10%), and M. iners (3%), as well as one Acheoplasma laidlawii strain (1%). MIC testing was performed on the axenic samples, and numerous strains of each species were resistant to either chlortetracycline or tylosin or both, with variable sensitivity to enrofloxacin. The strains of all species tested remained sensitive to tiamulin, except for one M. gallinaceum sample that demonstrated intermediate sensitivity. The mutation of A to G at position 2059 (A2059G) in the 23S rRNA gene, which is associated with macrolide resistance, was found in the South African M. gallisepticum and M. synoviae strains, as well as a clear correlation between macrolide resistance in M. gallinarum and M. gallinaceum and mutations G354A and G748A in the L4 ribosomal protein and 23S rRNA gene, respectively. No correlation between resistance and point mutations in the genes studied could be found for M. pullorum Only a few strains were resistant to enrofloxacin, apart from one M. synoviae strain with point mutation D420N, which has been associated with quinolone resistance, and no other known markers for quinolone resistance were found in this study. Proportionally more antimicrobial-resistant strains were detected in M. gallinaceum, M. gallinarum, and M. pullorum than in M. gallisepticum and M. synoviae Of concern, three M. gallinaceum strains showed multidrug resistance to chlortetracycline, tylosin, and oxytetracycline.IMPORTANCE Nonpathogenic poultry Mycoplasma species are often overlooked due to their lesser impact on poultry health and production compared to the OIE-listed pathogenic strains M. gallisepticum and M. synoviae The use of antimicrobials as in-feed growth promoters and for the control of mycoplasmosis is common in poultry production across the world. Here, we provide evidence that certain nonpathogenic Mycoplasma species are acquiring multidrug resistance traits. This would have significant implications if these species, for which no vaccines are applied, are able to transfer their antibiotic resistance genes to other mycoplasmas and bacteria that may enter the human food chain.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Infecções por Mycoplasma/veterinária , Mycoplasma/efeitos dos fármacos , Mycoplasma/isolamento & purificação , Doenças das Aves Domésticas/microbiologia , Animais , Galinhas , Clortetraciclina/farmacologia , Diterpenos/farmacologia , Testes de Sensibilidade Microbiana , Mycoplasma/classificação , Mycoplasma/genética , Infecções por Mycoplasma/microbiologia , Filogenia , África do Sul , Tilosina/farmacologia
15.
Transbound Emerg Dis ; 65(6): 1786-1796, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30024113

RESUMO

Diseases are among the greatest challenges to the rural poultry sector in sub-Saharan Africa. The lack of a sustainable poultry disease surveillance system and the possible existence of communities and occasions where the interaction between birds is high present an opportunity for targeted surveillance of poultry diseases in these regions. However, the establishment of such a system requires adequate knowledge of the sector in the targeted area. Zambia is an example of a developing country located in the tropics that faces the challenge of frequent poultry disease outbreaks. Consequently, an interview-based survey to study the poultry sector's market chain and social networks was conducted in Eastern Zambia to derive information required for configuring targeted surveillance. This survey involved a poultry value chain analysis that also included an assessment of trading practices to identify biosecurity hot spots within the chain that could be targeted for disease surveillance. A social network analysis of poultry movement within Eastern Zambia was also conducted using whole-network analysis and ego network analysis to identify poultry trade hubs that could be targeted for poultry disease surveillance based on their centrality within the network and their size and influence within their ego networks. Rural farmers, middlemen and market traders were identified as biosecurity risk hot spots whose poultry and utensils could be targeted for disease surveillance within the value chain. Furthermore, social network analysis identified four districts as poultry trade hubs that could be targeted for disease surveillance. This study is the first to formally describe poultry movement networks within Zambia and the surrounding region. Its findings provide data required to implement targeted surveillance in regions where resources are either inadequate or non-existent, and the results provide a deeper understanding of the cultural and practical constraints that influence trade in developing countries.


Assuntos
Surtos de Doenças/prevenção & controle , Doenças das Aves Domésticas/prevenção & controle , População Rural , Rede Social , Animais , Comércio , Surtos de Doenças/veterinária , Fazendeiros , Aves Domésticas , Doenças das Aves Domésticas/transmissão , Zâmbia
16.
Avian Dis ; 62(1): 50-56, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29620458

RESUMO

Mycoplasma gallinaceum is not among the most pathogenic mycoplasmas affecting poultry, but its continuous re-isolation from flocks in South Africa displaying typical signs of mycoplasmosis prompted us to revisit its role in respiratory disease. Specific-pathogen-free white leghorn chickens were co-challenged with either M. gallinaceum (MGC) and QX-like infectious bronchitis virus (IBV), or the more virulent Mycoplasm gallisepticum (MG) and IBV. No clinical signs were observed apart from sneezing in chickens challenged with IBV, MGC + IBV, and MG + IBV. On postmortem examination, one bird each in the MGC + IBV and IBV groups developed peritonitis or airsacculitis, respectively. In the tracheas, the MG + IBV group showed the most severe ciliary damage with a mean ciliostatic score of 32.40 compared to scores of 26.83 and 20.4 for the MGC + IBV and IBV groups, respectively. Corresponding tracheal lesions were recorded. Quantitation of the challenge pathogens by quantitative real-time PCR and real-time reverse transcriptase-PCR determined that MGC was shed in much higher titers from the trachea than MG, when co-infected with IBV. Interestingly, the presence of both MG and MGC appeared to enhance IBV replication in the tracheas of infected chickens, whereas the presence of IBV suppressed MG and MGC proliferation in the trachea. In general, the nonpathogenicity of M. gallinaceum in chickens was confirmed, but it was able to aggravate respiratory disease and pathogen proliferation with virulent QX-like IBV.


Assuntos
Galinhas , Infecções por Coronavirus/veterinária , Vírus da Bronquite Infecciosa/fisiologia , Infecções por Mycoplasma/veterinária , Mycoplasma gallisepticum/fisiologia , Mycoplasma gallisepticum/patogenicidade , Doenças das Aves Domésticas/microbiologia , Animais , Coinfecção/microbiologia , Coinfecção/veterinária , Coinfecção/virologia , Infecções por Coronavirus/virologia , Infecções por Mycoplasma/microbiologia , Doenças das Aves Domésticas/virologia , Reação em Cadeia da Polimerase em Tempo Real/veterinária , África do Sul , Organismos Livres de Patógenos Específicos , Virulência
17.
Avian Pathol ; 47(3): 261-270, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29451010

RESUMO

Mycoplasma gallisepticum (MG) is the primary cause of chronic respiratory disease in poultry. We investigated the protective efficacy of the live-attenuated ts-11 and 6/85 MG vaccines against a local MG strain and, in order to enhance signs and mimic a typical field situation, we co-infected birds with a virulent strain of QX-like infectious bronchitis virus (IBV). Both vaccines showed similar ability to protect infected chickens from clinical signs, although ts-11 performed slightly better. Despite the lower protection against clinical disease, 6/85-vaccinated birds had significantly (P ≤ 0.05) lower tracheal lesion scores and mucosal thickness at day 28 post-vaccination (7 days post-challenge [dpc] with MG, 2 dpc IBV) and day 31 post-vaccination (10 dpc MG challenge, 5 dpc IBV) compared to ts-11 vaccinated birds, but these difference was not significant at day 33 (12 dpc MG, 7 dpc IBV). Pathogen infection and replication was assessed by qPCR, and the 6/85 vaccine produced a more significant (P ≤ 0.05) reduction in MG replication in the lungs, kidneys and livers but enhanced late replication in bursae and caecal tonsils. In contrast, the ts-11 vaccine had a more pronounced reductive effect on replication in tracheas, air sacs, bursae and heart at days 28 and 31, yet increased replication in lungs. Interestingly, both vaccines provided non-specific protection against IBV challenge. The co-challenge model provided useful data on vaccine efficacy, especially on days 31 and 33, and tracheas, lungs, air sacs, kidneys, liver and caecal tonsils were the best organs to assess.


Assuntos
Vacinas Bacterianas/imunologia , Galinhas/imunologia , Vírus da Bronquite Infecciosa/imunologia , Infecções por Mycoplasma/veterinária , Mycoplasma gallisepticum/imunologia , Doenças das Aves Domésticas/prevenção & controle , Sacos Aéreos/microbiologia , Animais , Coinfecção/veterinária , Infecções por Mycoplasma/microbiologia , Infecções por Mycoplasma/prevenção & controle , Doenças das Aves Domésticas/microbiologia , Doenças das Aves Domésticas/virologia , Organismos Livres de Patógenos Específicos , Vacinação/veterinária
18.
Infect Genet Evol ; 57: 98-105, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29104094

RESUMO

Phylogenetic analyses of the complete genomes of the highly pathogenic avian influenza (HPAI) 2.3.2.1c H5N1 virus strains causing outbreaks in Nigeria's poultry population from 2014 to 2016 showed evidence of distinct co-circulating genotypes and the emergence of reassortant viruses. One of these reassortants became the predominant strain by 2016, and the NA protein of this strain possessed the V96A substitution known to confer reduced susceptibility to neuraminidase inhibiting antiviral drugs. Our findings also demonstrated evolutionary relationships between Nigerian isolates and European and Middle Eastern strains of H5N1 which provides further evidence for the proposed role of migratory birds in spreading the virus, although the involvement of the live poultry trade cannot be excluded. Efforts must be directed towards improving biosecurity and gaining the cooperation of poultry farmers for more effective control of HPAI, in order to mitigate the emergence of HPAI strains in Nigeria with biological properties that are potentially even more dangerous to animals and humans.


Assuntos
Evolução Molecular , Variação Genética , Genótipo , Virus da Influenza A Subtipo H5N1/classificação , Virus da Influenza A Subtipo H5N1/genética , Influenza Humana/epidemiologia , Influenza Humana/virologia , Genoma Viral , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Nigéria/epidemiologia , Filogenia , Vírus Reordenados/genética , Sequenciamento Completo do Genoma
19.
Genome Announc ; 5(34)2017 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-28839026

RESUMO

The first complete genome sequence of an African-origin Newcastle disease virus belonging to genotype XIII is described here. The virulent strain chicken/Zambia/Chiwoko/2015 was isolated from diseased chickens in 2015.

20.
Arch Virol ; 162(8): 2219-2230, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28361288

RESUMO

The genetic composition of an H5 subtype hemagglutinin gene quasispecies, obtained from ostrich tissues that had been infected with H5 subtype influenza virus was analysed using a next generation sequencing approach. The first evidence for the reiterative copying of a poly (U) stretch in the connecting peptide region in the haemagglutinin cleavage site (HACS) by the viral RNA-dependent RNA polymerase (RdRp) is provided. Multiple non-consensus species of RNA were detected in the infected host, corresponding to likely intermediate sequences between the putative low pathogenic precursor nucleotide sequence of the H5 influenza strain and the highly pathogenic avian influenza virus gene sequence. In silico analysis of the identified RNA sequences predicted that the intermediary H5 sequence PQREKRGLF plays an important role in subsequent mutational events that relocate the HACS coding region from stable base-paired RNA regions to a single-stranded bulge, thereby priming the connecting peptide coding region for RdRp slippage.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Virus da Influenza A Subtipo H5N1/genética , Influenza Aviária/virologia , RNA Polimerase Dependente de RNA/genética , Animais , Glicoproteínas de Hemaglutininação de Vírus da Influenza/isolamento & purificação , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Influenza Humana/virologia , Aves Domésticas/virologia , RNA Viral/genética
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