[show abstract][hide abstract] ABSTRACT: Low-pathogenic avian influenza viruses (LPAIVs) of subtype H9N2 have become widespread in poultry in many Asian countries with relevance to respiratory diseases of multifactorial origin. In Bangladesh, LPAIVs of subtype H9N2 co-circulate simultaneously with highly pathogenic avian influenza viruses (HPAIVs) of subtype H5N1 in commercial and backyard poultry. The aim of this study was to characterize LPAIVs of subtype H9N2 currently circulating in Bangladesh. The selected isolate A/Chicken/Bangladesh/VP01/2006 (H9N2) was propagated in chicken embryos. All eight gene segments were amplified by RT-PCR, cloned, and subjected to full-length sequencing. The sequence data obtained were compared with reference strains available in GenBank. Phylogenetic analysis of LPAIV H9N2 from Bangladesh revealed a close relationship to Indian, Pakistani and Middle Eastern isolates and identified an ancestor relationship to LPAIV H9N2 Quail/HK/G1/1997. The internal genes M and NP belong to lineage G1, whereas NS, PA, PB1 and PB2 belong to the prototype virus A/Chicken/Korea/38349-p96323/96. The internal genes showed high sequence homology to an HPAIV of subtype H7N3 from Pakistan, whereas the PB1 gene showed similarly high nucleotide homologies to recently circulating HPAIV H5N1 from Bangladesh, revealing two independent reassortment events. Examination of the hemagglutinin cleavage site of LPAIV H9N2 confirmed its low pathogenicity. The receptor-binding sites indicated a binding preference for human-type receptors. Several mutations in internal proteins are associated with increased virulence and altered host range, while other amino acids were found to be highly conserved among LPAIV H9N2 isolates.
Archives of Virology 01/2014; · 2.03 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two new strains of porcine circovirus type 2 virus (PCV2), strains Ha09 and Ha10, were detected in calves in Germany, and the complete genome of each virus has been sequenced and analyzed. Phylogenetic analysis suggests that these strains belong to the PCV2b genotype cluster, a highly prevalent genotype found worldwide.
[show abstract][hide abstract] ABSTRACT: Infectious laryngotracheitis virus (ILTV) continues to cause respiratory disease in Egypt in spite of vaccination. The currently available modified live ILTV vaccines provide good protection but may also induce latent infections and even clinical disease if they spread extensively from bird-to-bird in the field. Four field ILTV isolates, designated ILT-Behera2007, ILT-Giza2007, ILT-Behera2009, and ILT-Behera2010 were isolated from cross-bred broiler chickens. The pathogenicity based on intratracheal pathogenicity index, tracheal lesion score, and mortality index for chicken embryos revealed that ILT-Behera2007, ILT-Behera2009 and ILT-Behera2010 isolates were highly pathogenic whereas ILT-Giza2007 was non-pathogenic. To study the molecular epidemiology of these field isolates, the infected cell protein 4 gene was amplified and sequenced. Phylogenetic analysis revealed that ILT-Behera2007, ILT-Behera2009, and ILT-Behera2010 are chicken embryo origin (CEO) vaccine-related isolates while ILT-Giza2007 is a tissue culture origin vaccine-related isolate. These results suggest that CEO laryngotracheitis vaccine viruses could increase in virulence after bird-to-bird passages causing severe outbreaks in susceptible birds.
[show abstract][hide abstract] ABSTRACT: In domestic pigs strict control measures and the use of gene-deleted marker vaccines resulted in the elimination of pseudorabies virus (PrV) infections in many parts of Europe and North America. In free-roaming feral pigs and wild boar populations, however, serological surveys and monitoring in The Americas, Europe and North Africa provided serological and virological evidence that PrV is more widely distributed than previously assumed. Thus, there is a constant risk of spillover of PrV infection from wild pig populations to domestic animals which could require intervention to limit the infection in wild pigs. To investigate whether oral immunization of wild boar by live-attenuated PrV could be an option, wild boar and domestic pigs were orally immunized with 2×10(6) TCID(50) of the attenuated live PrV vaccine strain Bartha supplied either with a syringe or within a blister, and subsequently intranasally challenged with 10(6) TCID(50) of the highly virulent PrV strain NIA-3. Oral immunization with live-attenuated PrV was able to confer protection against clinical signs in wild boar and against transmission of challenge virus to naïve contact animals. Only two vaccinated domestic pigs developed neurological signs after challenge infection. Our results demonstrate that oral immunization against PrV infection in wild boar is possible. In case increasing PrV infection rates in wild boar may enhance the risk for spillover into domestic pig populations, oral immunization of wild boar against PrV in endemic areas might be a feasible control strategy.
[show abstract][hide abstract] ABSTRACT: Bovine leukemia virus (BLV) causes a persistent infection with provirus formation in B-lymphocytes. A real-time polymerase chain reaction (PCR) based on the conserved BLV polymerase (BLV pol) gene sequences was developed. Dually labeled probes were used to permit detection by the 5' exonuclease assay. The assay was validated with 350 samples of bovine peripheral blood mononuclear cells including 144 samples from BLV-seropositive animals worldwide (South America, Europe, Middle East, Australia) representing 5 of the recently described 7 BLV envelope-based genotypes. The BLV pol real-time PCR proved to be highly specific and sensitive with the detection of up to 1 copy of an internal control plasmid. The 95% confidence intervals for assay sensitivity and specificity were ≥ 98.27% and ≥ 98.33%, respectively. Restriction fragment length polymorphism and phylogenetic BLV pol-based sequence analysis of the investigated samples were performed and compared with the previous described BLV env-based genotypes. Grouping of the sequences based on the pol gene yielded similar results as the env gene-based assay.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 05/2012; 24(4):649-55. · 1.18 Impact Factor
[show abstract][hide abstract] ABSTRACT: Despite considerable host species barriers, interspecies transmissions of influenza A viruses between wild birds, poultry and pigs have been demonstrated repeatedly. In particular, viruses of the subtypes H1 and H3 were transmitted between pigs and poultry, predominantly turkeys, in regions with a high population density of both species. The recovery of a swine influenza H1N1 virus from a turkey flock in Germany in 2009 prompted us to investigate molecularly the subtype H1 viruses recently detected in wild birds, pigs and poultry.
The goal of this study was to investigate the relationship between H1N1 viruses originating from wild and domestic animals of Germany and to identify potential trans-species transmission or reassortment events.
Hemagglutinin and neuraminidase gene or full-length genome sequences were generated from selected, current H1N1 viruses from wild birds, pigs and turkeys. Phylogenetic analyses were combined with genotyping and analyses of the deduced amino acid sequences with respect to biologically active sites. Antigenic relationships were assessed by hemagglutination inhibition reactions.
Phylogenetic analysis of the hemagglutinin sequences showed that viruses from distinct H1 subgroups co-circulate among domestic animals and wild birds. In addition, these viruses comprised different genotypes and were distinguishable antigenically. An H1N1 virus isolated from a turkey farm in northern Germany in 2009 showed the highest similarity with the avian-like porcine H1N1 influenza viruses circulating in Europe since the late 1970s.
The data demonstrate the genetic and antigenic heterogeneity of H1 viruses currently circulating in domestic and wild animals in Germany and points to turkeys as a possible bridge between avian and mammalian hosts.
Influenza and Other Respiratory Viruses 07/2011; 5(4):276-84. · 1.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: From infection studies with cultured chicken cells and experimental mammalian hosts, it is well known that influenza viruses use the nonstructural protein 1 (NS1) to suppress the synthesis of interferon (IFN). However, our current knowledge regarding the in vivo role of virus-encoded NS1 in chickens is much more limited. Here, we report that highly pathogenic avian influenza viruses of subtypes H5N1 and H7N7 lacking fully functional NS1 genes were attenuated in 5-week-old chickens. Surprisingly, in diseased birds infected with NS1 mutants, the IFN levels were not higher than in diseased birds infected with wild-type virus, suggesting that NS1 cannot suppress IFN gene expression in at least one cell population of infected chickens that produces large amounts of the cytokine in vivo. To address the question of why influenza viruses are highly pathogenic in chickens although they strongly activate the innate immune system, we determined whether recombinant chicken alpha interferon (IFN-α) can inhibit the growth of highly pathogenic avian influenza viruses in cultured chicken cells and whether it can ameliorate virus-induced disease in 5-week-old birds. We found that IFN treatment failed to confer substantial protection against challenge with highly pathogenic viruses, although it was effective against viruses with low pathogenic potential. Taken together, our data demonstrate that preventing the synthesis of IFN is not the primary role of the viral NS1 protein during infection of chickens. Our results further suggest that virus-induced IFN does not contribute substantially to resistance of chickens against highly pathogenic influenza viruses.
Journal of Virology 05/2011; 85(15):7730-41. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: A natural reassortant influenza A virus consisting of seven genome segments from pandemic (H1N1) 2009 virus and a neuraminidase segment from a Eurasian porcine H1N1 influenza A virus was detected in a pig herd in Germany. The obvious reassortment compatibility between the pandemic (H1N1) 2009 and H1N1 viruses of porcine origin raises concern as to whether swine may become a reservoir for further reassortants of pandemic (H1N1) 2009 viruses with unknown implications for human health and swine production.
Journal of General Virology 02/2011; 92(Pt 5):1184-8. · 3.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: The generation of pandemic influenza A viruses of the previous century as well as that of the current influenza A/H1N1/2009 pandemic appear to be governed and preceded by reassortment events in other mammalian species. So far, it could not be shown that transmission of avian influenza viruses to humans will directly cause a pandemic. Zoonotic transmissions of avian and also of porcine influenza viruses of diverse subtypes have been repeatedly described. However, these events did not lead to further spread and establishment of these viruses. This is in contrast to the current A/H1N1/2009 viruses which already have started to outcompete seasonal human influenza viruses. The actual molecular key factors required for a successful exchange of genome segments between different influenza virus strains and which factors foster the consecutive spread of certain reassortant viruses in the human population remain to be pinpointed. It has been elucidated so far that newly introduced genome segments need to be compatible with both the remaining original segments and the human hosts.
[show abstract][hide abstract] ABSTRACT: Highly pathogenic avian influenza virus (HPAIV) H5N1 infections in felids have been reported in several countries. Feeding on infected birds has been suggested as potential source of infection.
The study aimed to verify gastrointestinal infection as possible portal of entry for HPAIV H5N1 in cats.
Four cats were infected oculo-nasopharyngeally with 10⁶ 50% egg infectious dose (EID(50) ) of HPAIV H5N1 A/cat/Germany/R606/2006. Two cats were infected intravenously with 10⁶ EID(50) and two cats were inoculated orally with 10⁷ EID(50) HPAIV embedded in gelatine capsules to mimic gastrointestinal exposure and to avoid virus contact to oropharyngeal or respiratory tissues. Cats were monitored for 6 days by physical examination, virus excretion, and peripheral blood lymphocyte counts. Blood chemical parameters (including AST, ALT, CPK, and TBIL) and viral excretion using pharyngeal and rectal swabs were analyzed.
Infected cats showed elevated body temperature up to 41·3°C starting from day 1 or 2 p.i. All infected cats excreted virus in pharyngeal swabs within 2 days p.i. co-inciding with the development of clinical signs (anorexia, depression, and labored breathing) irrespective of the infection route. Virus dissemination occurred through cell-free and cell-associated viremia. Infected cats developed lymphopenia, hepatic necrosis, pneumonia, and significantly elevated levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine phosphokinase (CPK), and TBIL.
The experiments show that the gastrointestinal tract can serve as portal for the entry of HPAIV H5N1 into cats. Infection routes used did not influence viral tissue tropism and course of disease.
Influenza and Other Respiratory Viruses 11/2010; 4(6):379-86. · 1.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: Rotaviruses are responsible for severe diarrhea in infants and substantial economic losses in animal husbandry worldwide. We investigated the oxidant/antioxidant status in rotavirus-infected human colon adenocarcinoma (Caco-2) cell line. Our results show that within the initial 48 h of infection the expression of the mitochondrial superoxide dismutase (MnSOD) is significantly increased, which correlates with a decrease in reactive oxygen species production, and with a lack of cellular glutathione depletion. During this period the mitochondria display a hyperpolarization of the inner membrane, which leads to an increased mitochondrial membrane potential. No increase in apoptosis was detected in the infected cultures. In contrast to many viral infections which cause redox imbalance in host cells, the described virus-host interaction suggests that rotavirus infection does not lead to an induction of oxidative stress, possibly to prolong cell survival and to allow for accumulation of viral particles before cell destruction and virus release.
[show abstract][hide abstract] ABSTRACT: To determine susceptibility of chickens, turkeys, and mice to pandemic (H1N1) 2009 virus, we conducted contact exposure and inoculation experiments. We demonstrated that chickens were refractory to infection. However, oculo-oronasally inoculated turkeys and intranasally inoculated mice seroconverted without clinical signs of infection.
[show abstract][hide abstract] ABSTRACT: Die Entstehung der pandemischen Influenzaviren des vergangenen Jahrhunderts werden ebenso wie die des derzeitigen pandemischen
Influenzavirus (H1N1) 2009 auf Reassortmentereignisse, das heißt auf den Austausch von Gensegmenten zwischen zwei oder mehreren
Influenza-A-Viren, zurückgeführt. Ein direkter Übergang eines Influenzavirus aus dem aviären Bereich auf den Menschen mit
der direkten Folge einer Pandemie konnte bislang nicht sicher belegt werden. Zoonotische Übertragungen von aviären Influenzaviren
verschiedenster Subtypen auf den Menschen sind mehrfach nachgewiesen worden, und auch mit porzinen Viren haben sich Menschen
wiederholt infiziert. Diese Ereignisse führten allerdings nicht zu einer weiteren Ausbreitung und dauerhaften Etablierung
der jeweiligen Viren in der humanen Population. Dies ist bei den neuen pandemischen Influenzaviren anders, die zum Teil die
etablierten saisonalen Stämme bereits verdrängt haben. Die eigentlichen molekularen Voraussetzungen für einen erfolgreichen
Gensegmentaustausch zwischen verschiedenen Influenzavirusstämmen und für die nachfolgende Etablierung von Reassortantenviren
beim Menschen sind noch unbekannt und bleiben weiterhin Gegenstand intensiver Forschung. Deutlich geworden ist bislang, dass
die neu eingeführten Genomsegmente sowohl zu den ursprünglichen Virusgenen kompatibel als auch an den menschlichen Organismus
angepasst sein müssen.
The generation of pandemic influenza A viruses of the previous century as well as that of the current influenza A/H1N1/2009
pandemic appear to be governed and preceded by reassortment events in other mammalian species. So far, it could not be shown
that transmission of avian influenza viruses to humans will directly cause a pandemic. Zoonotic transmissions of avian and
also of porcine influenza viruses of diverse subtypes have been repeatedly described. However, these events did not lead to
further spread and establishment of these viruses. This is in contrast to the current A/H1N1/2009 viruses which already have
started to outcompete seasonal human influenza viruses. The actual molecular key factors required for a successful exchange
of genome segments between different influenza virus strains and which factors foster the consecutive spread of certain reassortant
viruses in the human population remain to be pinpointed. It has been elucidated so far that newly introduced genome segments
need to be compatible with both the remaining original segments and the human hosts.
[show abstract][hide abstract] ABSTRACT: During the last decade reports of influenza A virus infections in dogs and cats draw considerable attention to veterinary practitioners and scientists in the fields of virology and epidemiology. Earlier experimental studies showed that dogs and cats are susceptible to influenza A virus infection, but animals did not develop clinical signs. In recent years transmission of influenza virus of subtype H3N8 from horses to dogs, however, was accompanied by severe clinical signs and the infection was shown to be transmitted to other pet dog populations in the US. In Asia respiratory disease caused by influenza virus H3N2 was documented in dogs and also a fatal infection with the highly pathogenic avian influenza virus (HPAIV) H5N1 was reported. Transmission of HPAIV H5N1 from infected poultry or wild birds to large felids and domestic cats has been reported from eight countries in Asia and Europe which caused considerable problems and concerns for both veterinary and public health in recent years. Experimentally the infection could also be transmitted from diseased to naive cats. Due to the heterogeneity of influenza viruses in their natural reservoirs of water fowl and the recent clinical natural infections in carnivores with influenza viruses of the subtypes H3 and H5, influenza virus infections should also be considered in dogs and cats with lower respiratory disease. The transmission of influenza A virus to carnivores from different mammalian and avian species may allow viral adaptation and therefore the epidemiological role of infected dogs and cats needs close attention.
Veterinary Immunology and Immunopathology 10/2009; 134(1-2):54-60. · 1.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: Influenza virus A/H1N1, which is currently causing a pandemic, contains gene segments with ancestors in the North American and Eurasian swine lineages. To get insights into virus replication dynamics, clinical symptoms and virus transmission in pigs, we infected animals intranasally with influenza virus A/Regensburg/D6/09/H1N1. Virus excretion in the inoculated pigs was detected in nasal swabs from 1 day post-infection (p.i.) onwards and the pigs developed generally mild symptoms, including fever, sneezing, nasal discharge and diarrhoea. Contact pigs became infected, shed virus and developed clinical symptoms similar to those in the inoculated animals. Plasma samples of all animals remained negative for virus RNA. Nucleoprotein- and haemagglutinin H1-specific antibodies could be detected by ELISA 7 days p.i. CD4(+) T cells became activated immediately after infection and both CD4(+) and CD8(+) T-cell populations expanded from 3 to 7 days p.i., coinciding with clinical signs. Contact chickens remained uninfected, as judged by the absence of virus excretion, clinical signs and seroconversion.
Journal of General Virology 08/2009; 90(Pt 9):2119-23. · 3.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: Highly pathogenic avian influenza viruses (HPAIV) differ from all other strains by a polybasic cleavage site in their hemagglutinin. All these HPAIV share the H5 or H7 subtype. In order to investigate whether the acquisition of a polybasic cleavage site by an avirulent avian influenza virus strain with a hemagglutinin other than H5 or H7 is sufficient for immediate transformation into an HPAIV, we adapted the hemagglutinin cleavage site of A/Duck/Ukraine/1/1963 (H3N8) to that of the HPAIV A/Chicken/Italy/8/98 (H5N2), A/Chicken/HongKong/220/97 (H5N1), or A/Chicken/Germany/R28/03 (H7N7) and generated the recombinant wild-type and cleavage site mutants. In contrast to the wild type, multicycle replication of these mutants in tissue culture was demonstrated by positive plaque assays and viral multiplication in the absence of exogenous trypsin. Therefore, in vitro all cleavage site mutants resemble an HPAIV. However, in chicken they did not exhibit high pathogenicity, although they could be reisolated from cloacal swabs to some extent, indicating enhanced replication in vivo. These results demonstrate that beyond the polybasic hemagglutinin cleavage site, the virulence of HPAIV in chicken is based on additional pathogenicity determinants within the hemagglutinin itself or in the other viral proteins. Taken together, these observations support the notion that acquisition of a polybasic hemagglutinin cleavage site by an avirulent strain with a non-H5/H7 subtype is only one among several alterations necessary for evolution into an HPAIV.
Journal of Virology 04/2009; 83(11):5864-8. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Analysis of all complete genome sequences of the pandemic influenza A(H1N1)v virus available as of 10 September 2009 revealed that two closely related but distinct clusters were circulating in most of the affected countries at the same time. The characteristic differences are located in genes encoding the two surface proteins - haemagglutinin and neuraminidase - and four internal proteins - the polymerase PB2 subunit, nucleoprotein, matrix protein M1 and the non-structural protein NS1. Phylogenetic inference was demonstrated by neighbour joining, maximum likelihood and Bayesian trees analyses of the involved genes and by tree construction of concatenated sequences.
Euro surveillance: bulletin europeen sur les maladies transmissibles = European communicable disease bulletin 01/2009; 14(46). · 5.49 Impact Factor
[show abstract][hide abstract] ABSTRACT: Highly pathogenic avian influenza virus (HPAIV) H5N1 of Asian origin continues to circulate in poultry and wild birds, causing considerable concern for veterinary and public health in Asia, Europe and Africa. Natural transmission of HPAIV H5N1 from poultry to humans, resulting in infections associated with high mortality, and from poultry or wild birds to large felids and domestic cats has been reported. Experimental infection of cats with HPAIV H5N1 derived from a human patient resulted in lethal disease. The role of cats in the adaptation of HPAIV H5N1 to mammals and vaccination regimens for the eventual protection of cats, however, remain to be elucidated. Here, it was shown that cats can be protected against a lethal high-dose challenge infection by an inactivated, adjuvanted heterologous H5N6 avian influenza virus vaccine. The challenge HPAIV H5N1 was derived from a naturally infected cat. In non-vaccinated cats, low-dose exposure resulted in asymptomatic infections with minimal virus excretion. As diseased cats can transmit the infection to naïve contact animals, the epidemiological role of H5N1-infected cats in endemically infected areas as a link between wild birds, poultry and humans needs close inspection, and vaccination of cats should be considered to reduce possible human exposure.
Journal of General Virology 05/2008; 89(Pt 4):968-74. · 3.13 Impact Factor