Geographical distribution of low pathogenic avian influenza viruses of domestic poultry in Vietnam and their genetic relevance with Asian isolates

From the avian influenza virus (AIV) outbreaks and market surveillances in Vietnam during November 2011 and March 2012, a total of 196 AIV were isolated. Although H5N1 highly pathogenic avian influenza (HPAI) was the most prevalent subtype in Vietnam, 57 low pathogenic avian influenza (LPAI) viruses were identified from mainly domestic ducks and some chickens. Of note, various subtypes of LPAI viruses were isolated from domestic ducks in Vietnam: H3 (n = 16), H4 (n = 4), H6 (n = 24), H7 (n = 1), and H9 (n = 10). Geographically, the LPAI viruses were identified in different regions of Vietnam. Phylogenetic analysis of HA and NA genes in LPAIV in Vietnam showed that some H3 (group I) and H4 subtypes AIV clustered with the viruses of several Asian isolates from domestic poultry and wild birds. However, the H6, H9, and some H3 (group II and III) subtypes AIV were closely related to isolates from domestic poultry in Southern China. In addition, whereas the N2 and N6 subtypes AIV belonged to the Eurasian lineage, the N8 subtype AIV was classified to be both of Eurasian and American lineage. These findings revealed that the regional trade and wild birds play a key role transmission of LPAIV in domestic ducks in Vietnam. Further surveillance at the intercountry level is needed to understand the epidemiology of these viruses and to cope with emergence of novel AIV types.

Multiple heterologous M2 extracellular domains presented on virus-like particles confer broader and stronger M2 immunity than live influenza A virus infection

The influenza M2 ectodomain (M2e) is poorly immunogenic and has some amino acid changes among isolates from different host species. We expressed a tandem repeat construct of heterologous M2e sequences (M2e5x) derived from human, swine, and avian origin influenza A viruses on virus-like particles (M2e5x VLPs) in a membrane-anchored form. Immunization of mice with M2e5x VLPs induced protective antibodies cross-reactive to antigenically different influenza A viruses and conferred cross protection. Anti-M2e antibodies induced by heterologous M2e5x VLPs showed a wider range of cross reactivity to influenza A viruses at higher levels than those by live virus infection, homologous M2e VLPs, or M2e monoclonal antibody 14C2. Fc receptors were found to be important for mediating protection by immune sera from M2e5x VLP vaccination. The present study provides evidence that heterologous recombinant M2e5x VLPs can be more effective in inducing protective M2e immunity than natural virus infection and further supports an approach for developing an effective universal influenza vaccine.

Molecular epidemiological investigation of velogenic Newcastle disease viruses from village chickens in Cambodia

Three isolates of Newcastle disease virus (NDV) were isolated from tracheal samples of dead village chickens in two provinces (Phnom Penh and Kampong Cham) in Cambodia during 2011-2012. All of these Cambodian NDV isolates were categorized as velogenic pathotype, based on in vivo pathogenicity tests and F cleavage site motif sequence ((112)RRRKRF(117)). The phylogenetic analysis and the evolutionary distances based on the sequences of the F gene revealed that all the three field isolates of NDV from Cambodia form a distinct cluster (VIIh) together with three Indonesian strains and were assigned to the genotype VII within the class II. Further phylogenetic analysis based on the hyper-variable region of the F gene revealed that some of NDV strains from Malaysia since the mid-2000s were also classified into the VIIh virus. This indicates that the VIIh NDVs are spreading through Southeast Asia. The present investigation, therefore, emphasizes the importance of further surveillance of NDV in neighboring countries as well as throughout Southeast Asia to contain further spreading of these VIIh viruses.

Characterization of mutations associated with the adaptation of a low-pathogenic H5N1 avian influenza virus to chicken embryos

Migratory waterfowls are the most common reservoir for avian influenza virus (AIV), thus viral adaptation is required for efficient replication in land fowls. To date, low pathogenic (LP) H5 subtype AIVs have been isolated from migratory waterfowls, and the adaptation of these viruses to land fowls might lead to the generation of highly pathogenic AIVs. Thus, A/wild duck/Korea/50-5/2009 (H5N1) LPAIV was passaged 20 times through embryonated chicken eggs (ECEs), and the resulting genetic and phenotypic changes were investigated. The pathogenicities of the early (50-5-E2) and final passage (50-5-E20) strains to chicken embryos were similarly high, but the 50-5-E20 titer was 100 times higher than that of 50-5-E2. 50-5-E20 showed 8 amino acid changes in PA (1), HA (4), NA (1), M1 (1) and M2 (1), with different frequencies among influenza A viruses (0-99.6%). The relevance of these changes, except H103Y in HA, to viral replication remains unknown. To investigate the roles of internal genes and mutations in HA and NA in viral replication, four recombinant viruses possessing combinations of HA and NA genes of 50-5-E2 and 50-5-E20 with 6 internal genes of PR8 were generated through reverse genetics. The embryo pathogenicities of the H5N1 recombinant viruses carrying internal PR8 genes were reduced, and the titers of the recombinant viruses with 50-5-E20 HA were higher than those with 50-5-E2 HA. Therefore, the identified mutations might be useful as chicken adaptation markers for the generation of high growth H5N1 recombinant viruses in ECEs.

Genetic and antigenic characteristics of H4 subtype avian influenza viruses in Korea and their pathogenicity in quails, domestic ducks and mice

In Korea, a nationwide surveillance programme was implemented in 2003 to identify highly pathogenic avian influenza viruses (AIVs). AIVs belonging to one of the most common haemagglutinin subtypes, H4, were isolated from two domestic ducks and 52 wild birds between 2004 and 2010. These H4 AIVs could be further classified into three neuraminidase subtypes: H4N6 (94.4%), H4N2 (3.7%) and H4N3 (1.9%). Phylogenetic analysis revealed that the H4 AIVs had a variety of genetic constellations, with at least nine different genotypes represented. The pathogenicity of these H4 viruses was assessed in quails, domestic ducks and mice. None of the H4 AIVs induced clinical signs in quails or domestic ducks. Viral shedding in quails was relatively high, and virus was recovered up to 5-7 days post-inoculation (p.i.) in oropharyngeal swabs, but the viruses replicated poorly in domestic ducks. Quails may act as an intermediate host in which AIVs are amplified and transmitted to other species. In mice, all of the AIVs were recovered efficiently at relatively high titres from the lungs up to 7 days p.i., demonstrating the potential for AIVs to infect mice directly without prior adaptation. None of the AIVs induced clinical signs nor was any lethal to infected mice. However, there was significant loss of body weight in mice infected with viruses of duck origin. It is suggested that the active surveillance of influenza viruses needs to be enhanced in domestic poultry as well as in wild birds, and that it should include assessment of pathogenicity in animal models.

Isolation of a reassortant H13N2 virus from a mallard fecal sample in South Korea

Background

Virus subtype H13N2, A/mallard/Kr/SH38-45/2010 (H13N2), was first isolated from a mallard fecal sample in South Korea.

Results

Phylogenetic analysis of all eight viral genes revealed that this virus emerged by genetic mixing between Eurasian and North American gene pools, and possibly between wild ducks and gulls. The H13 and N2 surface genes clustered together in a group with Eurasian isolates from gulls and wild birds, respectively. The PB2, PA, NP, M and NS segments belonged to the Eurasian lineage, whereas the PB1 gene clustered in the North American lineage. Furthermore, they showed a bird-dependent pattern in phylogenetic analysis: the M gene was similar to subtype H13 viruses within gulls, whereas other segments were similar to avian influenza viruses of other subtypes from wild ducks.

Conclusions

The data suggests that the novel reassortant H13N2 virus isolated in South Korea might have emerged by genetic reassortment between intercontinental and interspecies transmission in wild birds.

Highly pathogenic avian influenza (H5N1) outbreaks in wild birds and poultry, South Korea

Highly pathogenic avian influenza (H5N1) among wild birds emerged simultaneously with outbreaks in domestic poultry in South Korea during November 2010–May 2011. Phylogenetic analysis showed that these viruses belonged to clade 2.3.2, as did viruses found in Mongolia, the People’s Republic of China, and Russia in 2009 and 2010.

Anti-inflammatory effects of Hylomecon hylomeconoides in RAW 264.7 cells

BACKGROUND AND OBJECTIVES

Papaveraceae serve as a rich source of various alkaloids which have anti-inflammatory effect.

MATERIALS AND METHODS

In this study, we investigated the effect of Hylomecon hylomeconoides ethanol extract (HHE) on lipopolysaccharide (LPS)-induced NO and interleukin-6 (IL-6) production in RAW 264.7 cells.

RESULTS

HHE inhibited LPS-induced NO and IL-6 production. Moreover, HHE suppressed the phosphorylation of ERK1/2 and p38 in LPS-induced RAW 264.7 in a dose-dependent manner. Furthermore, major constituents, dihydrosanguinarine and 6-methoxydihydrosanguinarine, of the chloroform-soluble extract were analyzed.

CONCLUSIONS

Taken together, the results of this study indicate that the anti-inflammatory effects of HHE may occur via the inhibition of NO and IL-6 expression through the down-regulation of MAP kinase (ERK1/2, p38) phosphorylation in RAW 264.7 cells.

Antibacterial activity of bark of Alnus pendula against methicillin-resistant Staphylococcus aureus

BACKGROUND AND OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a rapidly growing health problem around the globe. Recently, there has been considerable interest in the use of plant materials as an alternative method to control pathogenic microorganisms. In this study we evaluated the antibacterial activity of bark of Alnus pendula against MRSA.

MATERIALS AND METHODS

The MIC determination was done using the microdilution broth method and bacterial growth was determined by measuring optical density using spectrophotometer.

RESULTS

Alnus pendula bark EtOH extract and fractions (F-1, -2, -3 and -4) were investigated against MRSA. The most active fractions (F-3 and F-4) led to the isolation of oregonin (ORE) and hirsutanone (HIR). These compounds were active against MRSA strains with minimum inhibitory concentrations (MICs) ranging from 31.25 to 250 microg/ml MIC and 2 MIC of HIR completely inhibited the growth of MRSA.

CONCLUSIONS

The bark EtOH extract of Alnus Pendula has potent antibacterial activity against MRSA.

Low pathogenic H7 subtype avian influenza viruses isolated from domestic ducks in South Korea and the close association with isolates of wild birds

We characterized low pathogenic avian influenza (LPAI) viruses of the H7 subtype that were isolated from domestic ducks and wild birds in South Korea from 2008 to 2011. A total of 20 H7 viruses were collected from live-bird markets (LBMs), duck farms and wild-bird habitats using avian influenza (AI) surveillance and epidemiological approaches. A phylogenetic analysis of the H7 viruses that were isolated from domestic ducks and wild birds demonstrated that they were separated into 12 genotypes (A-D and Wb-1-8, respectively), indicating genetic diversity. These H7 viruses were related to the recently isolated Eurasian LPAI H7 viruses and various influenza viruses that are circulating in Asia, including southern China and South Korea. The same genotype was not found between domestic poultry and wild-bird isolates; however, most of the H7 viruses in poultry (genotypes B and C) were closely related to the H7 virus isolated from a wild bird (genotype Wb-3). Animal-challenge studies revealed that certain H7 AI viruses replicated well only in chickens or ducks depending on the genotype, indicating that the pathogenicity of H7 viruses has the potential to be altered due to multiple reassortments, and these viruses can potentially expand their host range. Our results are evidence of abundant and frequent reassortment between H7 viruses in poultry and wild birds and emphasize the continuing need to monitor the evolutionary genetics of the influenza virus in poultry and wild birds.

H5N1 subtype highly pathogenic avian influenza virus isolated from healthy mallard captured in South Korea

On December 7, 2010, H5N1 highly pathogenic avian influenza virus was isolated from a healthy mallard captured at the Mankyung River in South Korea. Phylogenetic analysis showed that this virus was classified into clade 2.3.2 and closely related to H5N1 viruses isolated from wild birds in Mongolia, Russia and China in 2009 and 2010.

Survival rate of H5N1 highly pathogenic avian influenza viruses at different temperatures

The survival rate of Korean H5N1 highly pathogenic avian influenza (HPAI) viruses was investigated at different temperatures under the laboratory conditions. The estimated survival days for a starting viral concentration of 10(6.5) 50% egg infectious dose/0.1 mL were 930, 1,042, and 3,213 d at 4 degrees C; 226, 232, and 293 d at 20 degrees C; and 51, 55, and 58 d at 30 degrees C for A/chicken/Korea/ES/03, A/chicken/Korea/IS/06, and A/chicken/Korea/Gimje/08 (Gimje/08) viruses, respectively. The stability of the Gimje/08 virus was statistically significant compared with the other 2 viruses except for the data between Gimje/08 and A/chicken/Korea/IS/06 virus at 30 degrees C. This result indicated that the survival rate of 3 Korean HPAI viruses is different at various temperatures, which might have partially influenced the large scale of HPAI outbreak in Korea in 2008.

Antimicrobial activity of the constituents of Smallanthus sonchifolius leaves against methicillin-resistant Staphylococcus aureus

BACKGROUND AND OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) has been a serious problem as its infection is associated with higher mortality and increase cost worldwide. In the present study, the antibacterial activity of enhydrin, polymatin B, allo-schkuhriolide from the leaves of Smallanthus sonchifolius was investigated.

MATERIAL AND METHODS

Enhydrin, polymatin B, allo-schkuhriolide from the leaves of Smallanthus sonchifolius were tested for antimicrobial activity using micro dilution broth method against 2 strains of ATCC 33591, ATCC 25923 and 15 strains of clinical isolates MRSA.

RESULTS

The antibacterial activity of Smallanthus sonchifolius can safely be attributed to enhydrin as polymatin B, and allo-schkuhriolide are not showing any activity against Staphylococcus aureus strains. The enhydrin showed good antibacterial activity against all tested strains (MIC = 125-500 microg/ml).

DISCUSSION

These results suggest that only enhydrin can be considered as an antibacterial drug against MRSA.

Characterization of H5N2 influenza viruses isolated in South Korea and their influence on the emergence of a novel H9N2 influenza virus

We characterized low pathogenic avian influenza (LPAI) H5N2 and H9N2 viruses isolated in South Korea from 2008 to 2009. Genetic analysis of the H5N2 viruses isolated from wild birds and domestic ducks demonstrated that they were related to the recently isolated southern Chinese LPAI H5 viruses and various influenza viruses circulating in Eurasia. Three H9N2 viruses obtained at live bird markets and duck farms were reassortant viruses generated from the H5N2 viruses of domestic ducks and the H9N2 virus endemic in Korean chickens. The H5N2 viruses did not replicate well in experimentally infected chickens and mice, but novel H9N2 viruses, without pre-adaptation, were recovered at high titres in chickens. Our results show that reassortment between H5N2 and H9N2 viruses must have occurred in domestic ducks and may have contributed to the diversity expansion of the gene pool, which has potential to alter the pathogenicity and host range of the influenza virus.

Protection of chickens from Newcastle disease with a recombinant baculovirus subunit vaccine expressing the fusion and hemagglutininneuraminidase proteins

Recombinant baculoviruses containing the fusion (F) and hemagglutinin-neuraminidase (HN) glycoprotein gene of the viscerotropic velogenic (vv) Newcastle disease virus (NDV) isolate, Kr-005/00, and a lentogenic La Sota strain of the NDV were constructed in an attempt to develop an effective subunit vaccine to the recent epizootic vvNDV. The level of protection was determined by evaluating the clinical signs, mortality, and virus shedding from the oropharynx and cloaca of chickens after a challenge with vvNDV Kr-005/00. The recombinant ND F (rND F) and recombinant HN (rND HN) glycoproteins derived from the velogenic strain provided good protection against the clinical signs and mortality, showing a 0.00 PI value and 100% protection after a booster immunization. On the other hand, the combined rND F + HN glycoprotein derived from the velogenic strain induced complete protection (0.00 PI value and 100% protection) and significantly reduced the amount of virus shedding even after a single immunization. The rND F and rND HN glycoproteins derived from the velogenic strain had a slightly, but not significantly, greater protective effect than the lentogenic strain. These results suggest that the combined rND F + HN glycoprotein derived from vvNDV can be an ideal subunit marker vaccine candidate in chickens in a future ND eradication program.

Genetic diversity of avian infectious bronchitis virus isolates in Korea between 2003 and 2006

Thirty-three field isolates of avian infectious bronchitis virus (IBV) were recovered from commercial chicken flocks in Korea between 2003 and 2006 and were characterized phylogenetically by nucleotide sequence analysis of the IBV S1 gene hyper-variable region. Our phylogenetic analysis revealed that recent field isolates of IBV formed at least three distinct phylogenetic types, including K-I, K-II, and K-III. K-I type IBV consisted of indigenous, 13 IBV isolates which evolved from the Kr-EJ/95 strain and then separated into the lineages of type K-Ia and type K-Ib. K-II type IBV isolates (n = 19) were closely related to nephropathogenic IBV variants from China and Japan. The K-III type isolate (Kr/D064/05), first identified by this study, was closely related to enteric IBV variants from the Chinese strains that cause proventriculitis. Sequence comparisons showed amino acid differences of >27.5% between IBV types. The molecular epidemiologic characteristics of IBV field isolates are briefly discussed.

Bio-separation of toxic arsenate ions from dilute solutions by native and pretreated biomass of Aspergillus fumigatus in batch and column mode: effect of biomass pretreatment

The sorption of As(V) from aqueous solution onto live and pretreated biomass of Aspergillus fumigatus was studied. The studies on optimization of contact time, adsorbent dosage and pH showed that the FeCl(3) treated and FeSO(4) treated biomass had the maximum capacity to adsorb As(V) while acid treated biomass was found to be minimum. Adsorption parameters were determined using both Langmuir and Freundlich isotherm models. The maximum adsorption capacity of 0.054 mg/g was observed in FeCl(3) treated and FeSO(4) treated biomasses. Column mode studies were conducted using FeSO(4) treated biomass to compare its efficacy with batch mode to adsorb As(V). Batch mode experiments proved to be efficient. Desorption studies were also carried out with dilute sodium hydroxide to recover both the adsorbent and adsorbate.

Organic micro-pollutant removal in liquid-phase using carbonized silk cotton hull

Phenolic compounds constitute one of the major pollutants in the modern world. Although many physical and chemical treatment technologies for their removal exist, most of them are economically not feasible. The present study was aimed at using silk cotton hull, a potent agricultural waste as an adsobent for removal of 2,4-dichlorophenol (2,4-DCP), which was used as a model phenolic compound. The process parameters were investigated and optimized conditions were determined. The equilibrium time was found to be 60 and 80 min for 10 and 20 mg/L and 100 min for 30 and 40 mg/L 2,4-DCP concentrations, respectively. Among the kinetic models applied, pseudo-second order model fitted well. The maximum adsorption capacity was 16.0 mg/g by Langmuir isotherm. Acidic pH was found favorable for the adsorption of 2,4-DCP. Studies on pH effect and desorption seemed to show that chemisorption played a major role in the adsorption process. In thermodynamic study, the change in entropy (DeltaS0) and heat of adsorption (DeltaH0) of silk cotton hull carbon (SCHC) was estimated as 14.01 J/(mol x K) and 3.04 kJ/mol, respectively. SCHC as adsorbent for removal of 2,4-DCP from aqueous solution, is effective, inexpensive, indigenous, reusable, has low treatment time and is easily available in large quantities as waste there by significantly lowers the cost of wastewater treatment.

Continuing evolution of H9 influenza viruses in Korean poultry

We analyzed the evolution of H9 influenza viruses isolated from Korean chicken farms from 2002 to 2004. Korean H9 viruses formed two antigenically distinct groups: those isolated from 1996 to mid-2003, and those isolated from late 2003 through 2004. Most of the 2004 isolates showed greater cross-reactivity with the second group than with the first group. Phylogenetic analysis of the 12 viruses studied revealed three genotypes of H9N2 viruses and showed that reassortment had occurred. One isolate, Ck/Kor/164/04, belonged to the H9N8 subtype. Its HA and PB1 genes were similar to those of the H9N2 viruses, but its other genes were closely related to H3N8 viruses. This report is the first (to our knowledge) of H9N8 infection in this host. The pathogenicity of the early isolates altered due to antigenic drift and reassortment, leading to H9 avian influenza viruses in Korea that potentially can expand their host range to mammalians.

Effects of Homologous and Heterologous Neuraminidase Vaccines in Chickens Against H5N1 Highly Pathogenic Avian Influenza

The 2004 Asian H5N1 epizootic outbreak indicates the urgent need for vaccines against highly pathogenic avian influenza (HPAI) virus. The manufacture of inactivated whole-virus vaccines from HPAI viruses by traditional methods is not feasible for safety reasons as well as technical issues. The low pathogenic avian influenza A/wild bird feces/CSM2/02 (H5N3) virus was used as a heterologous neuraminidase vaccine, and HPAI A/CK/Korea/ES/03 (H5N1) virus was used as a homologous neuraminidase vaccine. Protection efficacy of both vaccines was evaluated by clinical signs, mortality rates, and virus shedding from oropharynx and cloaca of vaccinated chickens after challenge with HPAI A/CK/Korea/ES/03 (H5N1) virus. One dose of 128 hemagglutinin (HA) homologous H5N1 vaccine induced 100% protection in mortality and prevented viral shedding completely after lethal dose virus challenge, whereas one dose of 64 HA unit of heterologous H5N3 vaccine only induced 50% protection in mortality, and it did not prevent viral shedding. However, two doses at a 3-wk interval of 64 HA unit of heterologous H5N3 vaccine as well as one dose of 1024 HA unit of heterologous H5N3 vaccine induced 100% survival rate and could prevent viral shedding completely. Furthermore, we could differentiate the sera of infected birds from those of vaccinated birds by indirect immunofluorescent antibody test. These results suggest that heterologous neuraminidase H5N3 vaccine could be a useful tool for the control of H5N1 HPAI epidemic in poultry.

Highly pathogenic avian influenza (H5N1) in the commercial domestic ducks of South Korea

The present study reports the clinical, virological and pathological findings observed in a natural outbreak of highly pathogenic avian influenza in farmed commercial ducks. The ducks developed clinical signs, including mild respiratory distress, depression, mild diarrhoea, loss of appetite and increasing mortality (up to 12%). At necropsy, multifocal mottled necrosis was commonly found in the pancreas with splenomegaly, hepatomegaly, and swollen kidneys. Microscopically, there was necrotized pancreatitis and hepatitis, and lymphocytic meningoencephalitis and myocarditis. Influenza viral antigen was demonstrated in areas closely associated with histopathological lesion. Avian influenza virus was isolated from the caecal tonsil, faeces, and kidney of the domestic ducks. The isolated virus was identified as a highly pathogenic H5N1, with a haemagglutinin proteolytic cleavage site deduced amino acid sequence of ... QREKRKKR/GLFGAIAG ... In order to determine the pathogenicity of the isolate, eight 6-week-old specific pathogen free chickens were inoculated intravenously with the virus, and all birds died within 24 h after inoculation. This is the first report of an outbreak of highly pathogenic avian influenza with clinical signs in commercial domestic ducks in South Korea.