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1.
PLoS One ; 11(9): e0162375, 2016.
Article in English | MEDLINE | ID: mdl-27631618

ABSTRACT

Avian influenza viruses of H5 subtype can cause highly pathogenic disease in poultry. In March 2014, a new reassortant H5N6 subtype highly pathogenic avian influenza virus emerged in Lao People's Democratic Republic. We have assessed the pathogenicity, pathobiology and immunological responses associated with this virus in chickens. Infection caused moderate to advanced disease in 6 of 6 chickens within 48 h of mucosal inoculation. High virus titers were observed in blood and tissues (kidney, spleen, liver, duodenum, heart, brain and lung) taken at euthanasia. Viral antigen was detected in endothelium, neurons, myocardium, lymphoid tissues and other cell types. Pro-inflammatory cytokines were elevated compared to non-infected birds. Our study confirmed that this new H5N6 reassortant is highly pathogenic, causing disease in chickens similar to that of Asian H5N1 viruses, and demonstrated the ability of such clade 2.3.4-origin H5 viruses to reassort with non-N1 subtype viruses while maintaining a fit and infectious phenotype. Recent detection of influenza H5N6 poultry infections in Lao PDR, China and Viet Nam, as well as six fatal human infections in China, demonstrate that these emergent highly pathogenic H5N6 viruses may be widely established in several countries and represent an emerging threat to poultry and human populations.


Subject(s)
Chickens/microbiology , Influenza A virus/pathogenicity , Influenza in Birds/virology , Reassortant Viruses/pathogenicity , Animals , Dogs , Influenza A virus/isolation & purification , Laos , Madin Darby Canine Kidney Cells , Reassortant Viruses/isolation & purification , Viral Load
2.
Emerg Infect Dis ; 21(3): 511-6, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25695754

ABSTRACT

In March 2014, avian influenza in poultry in Laos was caused by an emergent influenza A(H5N6) virus. Genetic analysis indicated that the virus had originated from reassortment of influenza A(H5N1) clade 2.3.2.1b, variant clade 2.3.4, and influenza A(H6N6) viruses that circulate broadly in duck populations in southern and eastern China.


Subject(s)
Influenza A virus/classification , Influenza A virus/genetics , Influenza in Birds/epidemiology , Influenza in Birds/virology , Reassortant Viruses , Animals , Chick Embryo , Hemagglutination Inhibition Tests , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Laos/epidemiology , Molecular Sequence Data , Neuraminidase/genetics , Phylogeny , Poultry , Viral Proteins/genetics
3.
Trop Anim Health Prod ; 41(6): 913-20, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19043796

ABSTRACT

Classical swine fever (CSF) is a highly contagious and severe viral disease of swine resulting in substantial production losses in different farming systems in many regions of the world. The accurate and rapid detection of CSF outbreaks is reliant on sensitive and specific laboratory testing and is a key component of disease control. Specific detection of CSF virus can be achieved by virus isolation in tissue culture, antigen capture or the detection of viral RNA using molecular techniques. In order to reduce the time taken to achieve a diagnostic result and simplify testing methods, an antigen capture ELISA using immunomagnetic beads (IMB) as the solid phase was developed and compared to a microplate-based antigen capture (AC)-ELISA. The IMB-ELISA has up to 64-fold greater analytical sensitivity than the AC-ELISA and initial estimates of diagnostic sensitivity and specificity are 100%. The IMB-ELISA has a highly robust, rapid and stable test format and is simpler to perform than the AC-ELISA. The IMB-ELISA has the added advantage that a result can be sensitively and specifically determined by eye, lending it to the possibility of adaptation to a near-to-field test with minimal equipment or expertise needed.


Subject(s)
Antigens, Viral/analysis , Classical Swine Fever Virus/immunology , Immunomagnetic Separation/veterinary , Swine Diseases/diagnosis , Swine Diseases/virology , Animals , Enzyme-Linked Immunosorbent Assay/veterinary , Immunomagnetic Separation/methods , Swine , Swine Diseases/immunology
4.
Virus Res ; 97(2): 151-7, 2003 Nov.
Article in English | MEDLINE | ID: mdl-14602208

ABSTRACT

A recombinant porcine adenovirus expressing the classical swine fever virus (CSFV) gp55 gene (rPAdV-gp55) was administered to commercially available outbred pigs via the subcutaneous or oral route and their susceptibility to 'in contact' challenge with classical swine fever determined. Animals vaccinated subcutaneously with a single dose of recombinant vaccine and challenged by 'in contact' exposure were protected from disease, whereas pigs given an equivalent single oral dose did not survive challenge. However, pigs given two oral doses of rPAdV-gp55, 22 days apart, were completely protected from disease. In addition, two doses of rPAdV-gp55 given subcutaneously was shown to boost CSFV neutralising antibody compared with a single dose, but neither a single dose nor two doses given orally induced detectable neutralising antibody responses.


Subject(s)
Adenoviruses, Porcine/genetics , Classical Swine Fever Virus/immunology , Classical Swine Fever/prevention & control , Viral Envelope Proteins/genetics , Viral Envelope Proteins/immunology , Viral Vaccines/administration & dosage , Administration, Oral , Animals , Immunization Schedule , Injections, Subcutaneous , Swine , Vaccination/veterinary , Vaccines, Synthetic/administration & dosage
5.
J Virol Methods ; 99(1-2): 41-51, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11684302

ABSTRACT

Rapid immune plaque assays have been developed to quantify biohazard level 4 agents Hendra and Nipah viruses and detect neutralising antibodies to both viruses. The methods rely on the fact that both viruses rapidly generate large syncytia in monolayers of Vero cells within 24 h and that monospecific antiserum to the Hendra virus phosphoprotein (P) detects that protein in both Hendra and Nipah virus-induced syncytia after methanol fixation of virus-infected cells. The P protein is a constituent of the ribonucleoprotein core of the viruses and a component of the viral RNA-dependent RNA polymerase and is made in significant amounts in infected cells. In the immune plaque assay, anti-P antibody is localised by an alkaline phosphatase-linked second antibody and the Western blot substrates 5-bromo-4-chloro-3-indolyl phosphate and p-nitro blue tetrazolium. A modification of the rapid immune plaque assay was also used to detect antibodies to Nipah virus in a panel of porcine field sera from Malaysia and the results showed good agreement between the immune plaque assay and a traditional serum neutralisation test. After methanol fixation, plates can be stored for up to 7 months and may be used in the immune plaque assay to complement the enzyme-linked immunosorbent assay screening of sera for antibodies to Nipah virus. At present, all enzyme-linked immunosorbent assay positive sera are subject to confirmatory serum neutralisation tests. Use of the immune plaque assay may reduce the number of sera requiring confirmatory neutralisation testing for Nipah virus antibodies under biohazard level 4 conditions by identifying those that generate false positive in the enzyme-linked immunosorbent assay.


Subject(s)
Antibodies, Viral/blood , Paramyxoviridae Infections/virology , Paramyxovirinae/immunology , Paramyxovirinae/isolation & purification , Viral Plaque Assay , Animals , Cattle , Cell Line , Chlorocebus aethiops , Cricetinae , Dogs , Humans , Mice , Mice, Inbred BALB C , Neutralization Tests , Paramyxovirinae/growth & development , Time Factors , Vero Cells
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