Journal of Microbiology

Volume 49(2); April 2011

Review

REVIEW] Candida albicans, a Major Human Fungal Pathogen: Joon Kim , Peter Sudbery; J. Microbiol. 2011;49(2):171-177. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-1064-7

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373 Citations

Abstract: Candida albicans is the most common human fungal pathogen (Beck-Sague and Jarvis, 1993). It is normally a harmless commensal organism. However, it is a opportunistic pathogen for some immunologically weak and immunocompromised people. It is responsible for painful mucosal infections such as the vaginitis in women and oral-pharangeal thrush in AIDS patients. In certain groups of vulnerable patients it causes severe, life-threatening bloodstream infections and it causes severe, life-threatening bloodstream infections and subsequent infections in the internal organs. There are various fascinating features of the C. albicans life cycle and biology that have made the pathogen the subject of extensive research, including its ability to grow in unicellular yeast, psudohyphal, and hyphal forms (Fig. 1A); its ability to switch between different but stable phenotypic states, and the way that it retains the ability to mate but apparently loses the ability to go through meiosis to complete the sexual cycle. This research has been greatly facilitated by the derivation of the complete C. albicans genome sequence (Braun et al., 2005), the development of a variety of molecular tools for gene manipulation, and a store of underpinning knowledge of cell biology borrowed from the distantly related model yeast Saccharomyces cerevisiae (Berman and Sudbery, 2002; Noble and Johnson, 2007). This review will provide a brief overview of the importance of C. albicans as a public health issue, the experimental tools developed to study its fascinating biology, and some examples of how these have been applied.

Research Support, Non-U.S. Gov'ts

Isolation and Characterization of a Family VII Esterase Derived from Alluvial Soil Metagenomic Library: Weixin Tao , Myung Hwan Lee , Jing Wu , Nam Hee Kim , Seon-Woo Lee; J. Microbiol. 2011;49(2):178-185. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-1102-5

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Abstract: A novel esterase gene, estDL30, was isolated from an alluvial metagenomic library using function-driven screening. estDL30 consisted of 1,524 nucleotides and encoded a 507-amino acid protein. Sequence analysis revealed that EstDL30 is similar to many type B carboxylesterases, containing a G-E-S-A-G pentapeptide with a catalytic Ser residue. Phylogenetic analysis suggested that EstDL30 belongs to the family VII lipases, together with esterases from Bacillus subtilis (P37967), Streptomyces coelicolor A3(2) (CAA22794), and Arthrobacter oxydans (Q01470). Purified EstDL30 showed its highest catalytic efficiency toward p-nitrophenyl butyrate, with a kcat of 229.3 s-1 and kcat/Km of 176.4 s-1mM-1; however, little activity was detected when the acyl chain length exceeded C8. Biochemical characterization of EstDL30 revealed that it is an alkaline esterase that possesses maximal activity at pH 8 and 40°C. The effects of denaturants and divalent cations were also investigated. EstDL30 tolerated well the presence of methanol and Tween 20. Its activity was strongly inhibited by 1 mM Cu2+ and Zn2+, but stimulated by Fe2+. The unique properties of EstDL30, its high activity under alkaline conditions and stability in the presence of organic solvents, may render it applicable to organic synthesis.

Correlations of Fecal Bacterial Communities with Age and Living Region for the Elderly Living in Bama, Guangxi, China: Liang Zhao , Xuewei Qiao , Jun Zhu , Xiaoying Zhang , Jingli Jiang , Yanling Hao , Fazheng Ren; J. Microbiol. 2011;49(2):186-192. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0405-x

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Abstract: Bama County (Guangxi, China) is famous for its longevous population. In this study, intestinal microflora of 17 healthy elderly subjects of different ages and from different regions (rural and urban) in Bama, were analyzed by denaturing gradient gel electrophoresis (DGGE). Significant effects of age and living region on the whole intestinal bacterial communities were observed by redundancy analysis (RDA). A total of 11 bacterial strains that were correlated with age and living region were identified using a t-value biplot combined with band sequencing. Four bacterial strains were correlated with both age and living region of the elderly in Bama. Two Bacteroides strains and one Ruminococcaceae strain were abundant in the rural, younger elderly; conversely, one Desulfovibrio strain was high in the urban, older elderly. Another Bacteroidetes strain was only correlated with the participant’s age, and its abundance increased with the age of the elderly. The richness of one Clostridium sordellii strain, which was only correlated with the elderly living region, was high in the urban elderly. The study also found five other novel bacterial strains that were correlated with the age or living region of the elderly in Bama. These results expand our understanding of age- and region-effects on the intestinal microflora of the elderly and raise the possibility of developing probiotics originating from centenarians.

Inhibitory Effect of Lactobacillus reuteri on Periodontopathic and Cariogenic Bacteria: Mi-Sun Kang , Jong-Suk Oh , Hyun-Chul Lee , Hoi-Soon Lim , Seok-Woo Lee , Kyu-Ho Yang , Nam-Ki Choi , Seon-Mi Kim; J. Microbiol. 2011;49(2):193-199. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0252-9

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Abstract: The interaction between Lactobacillus reuteri, a probiotic bacterium, and oral pathogenic bacteria have not been studied adequately. This study examined the effects of L. reuteri on the proliferation of periodontopathic bacteria including Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannerella forsythia, and on the formation of Streptococcus mutans biofilms. Human-derived L. reuteri strains (KCTC 3594 and KCTC 3678) and rat-derived L. reuteri KCTC 3679 were used. All strains exhibited significant inhibitory effects on the growth of periodontopathic bacteria and the formation of S. mutans biofilms. These antibacterial activities of L. reuteri were attributed to the production of organic acids, hydrogen peroxide, and a bacteriocin-like compound. Reuterin, an antimicrobial factor, was produced only by L. reuteri KCTC 3594. In addition, L. reuteri inhibited the production of methyl mercaptan by F. nucleatum and P. gingivalis. Overall, these results suggest that L. reuteri may be useful as a probiotic agent for improving oral health.

Journal Article

Screening-Level Assays for Potentially Human-Infectious Environmental Legionella spp.: Helen Y. Buse , Abby Brehm , Jorge W. Santo Domingo , Nicholas J. Ashbolt; J. Microbiol. 2011;49(2):200-207. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0233-z

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Abstract: In spite of the fact that various Legionella species are isolated from nonclinical water settings, there is no standard method to determine whether environmental legionellae may be infectious to humans. Here we provide a screening-level approach based on an in vivo murine (A/J mouse) model and three in vitro proliferation assays using Acanthamoeba polyphaga, and THP-1 human and J774 murine macrophage cell lines to identify potentially human-infectious legionellae. As an initial demonstration the infectivity potential of three clinical (Legionella pneumophila, L. longbeacheae, and L. micdadei) and three environmental (L. dumoffii, L. maceachernii, and L. sainthelensi) legionellae were evaluated. A/J mice were intranasally infected and by 6 h post infection (p.i.), there were significant bacterial titers in the lungs. L. pneumophila, L. dumoffii, and L. micdadei densities were higher than L. longbeacheae, L. maceacherni, and L. sainthelensi at 24 h p.i. However, only L. pneumophila and L. micdadei persisted in the lungs after 48 h, indicating that the other isolates were rapidly cleared. Results from the in vitro assays showed that only L. pneumophila significantly multiplied within A. polyphaga, THP-1 and J774 cells after 72 h, but lysis of any of the in vitro hosts also flagged the strains for potential concern (e.g. L. dumoffii and L. micdadei). The results demonstrate the value of using multiple approaches to assess the potential level of pathogenicity of Legionella strains isolated from different environmental matrices.

Research Support, Non-U.S. Gov't

Physiological and Metabolic Responses for Hexadecane Degradation in Acinetobacter oleivorans DR1: Jaejoon Jung , Jaemin Noh , Woojun Park; J. Microbiol. 2011;49(2):208-215. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0395-8

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31 Citations

Abstract: The hexadecane degradation of Acinetobacter oleivorans DR1 was evaluated with changes in temperature and ionic salt contents. Hexadecane degradation of strain DR1 was reduced markedly by the presence of sodium chloride (but not potassium chloride). High temperature (37°C) was also shown to inhibit the motility, biofilm formation, and hexadecane biodegradation. The biofilm formation of strain DR1 on the oil-water interface might prove to be a critical physiological feature for the degradation of hexadecane. The positive relationship between biofilm formation and hexadecane degradation could be observed at 30°C, but not at low temperatures (25°C). Alterations in cell hydrophobicity and EPS production by temperature and salts were not correlated with biofilm formation and hexadecane degradation. Our proteomic analyses have demonstrated that metabolic changes through the glyoxylate pathway are important for efficient degradation of hexadecane. Proteins involved in fatty acid metabolism, gluconeogenesis, and oxidative stress defense proteins appear to be highly expressed during biodegradation of hexadecane. These results suggested that biofilm formation and oxidative stress defense are important physiological responses for hexadecane degradation along with metabolic switch to glyoxylate pathway in strain DR1.

Journal Article

The Effect of Lipid Supplements on Ruminal Bacteria in Continuous Culture Fermenters Varies with the Fatty Acid Composition: Ramesh B. Potu , Amer A. AbuGhazaleh , Darcie Hastings , Karen Jones , Salam A. Ibrahim; J. Microbiol. 2011;49(2):216-223. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0365-1

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Abstract: A single flow continuous culture fermenter system was used in this study to investigate the influence of dietary lipid supplements varying in their fatty acid content on the DNA concentration of selected rumen bacteria. Four continuous culture fermenters were used in a 4×4 Latin square design with four periods of 10 d each. Treatment diets were fed at 45 g/d (DM basis) in three equal portions during the day. The diets were: 1) control (CON), 2) control with animal fat source (SAT), 3) control with soybean oil (SBO), and 4) control with fish oil (FO). Lipid supplements were added at 3% of diet DM. The concentrations of total volatile fatty acids and acetate were not affected (P>0.05) by lipid supplements. Concentrations of propionate, iso-butyrate, valerate and iso-valerate were highest (P<0.05) with the FO diet compared with the other treatment diets. The concentration of t11 C18:1 (vaccenic acid, VA) in effluents increased (P<0.05) with SBO and FO diets and was highest with the SBO diet. The concentrations of C18:0 in effluents were lowest (P<0.05) for the FO diet compared with the other treatment diets. Concentrations of DNA for Anaerovibrio lipolytica, and Butyrivibrio proteoclasticus in fermenters were similar (P>0.05) for all diets. The DNA concentrations of Butyrivibrio fibrisolvens and Ruminococcus albus in fermenters were lowest (P<0.05) with the FO diet but were similar (P>0.05) among the other treatment diets. Selenomonas ruminantium DNA concentration in fermenters was highest (P<0.05) with the FO diet. In conclusion, SBO had no effect on bacterial DNA concentrations tested in this study and the VA accumulation in the rumen observed on the FO diet may be due in part to FO influence on B. fibrisolvens, R. albus, and S. ruminantium.

Research Support, Non-U.S. Gov't

Seasonal Abundance and Distribution of Vibrio Species in the Treated Effluents of Wastewater Treatment Facilities in Suburban and Urban Communities of Eastern Cape Province, South Africa: Etinosa O. Igbinosa , Chikwelu L. Obi , Anthony I. Okoh; J. Microbiol. 2011;49(2):224-232. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0227-x

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20 Citations

Abstract: We assessed the seasonal abundance and distribution of Vibrio species as well as some selected environmental parameters in the treated effluents of two wastewater treatment plants (WWTP), one each located in a suburban and urban community of Eastern Cape Province, South Africa. Vibrio population density ranged from 2.1×101 to 4.36×104 CFU/ml in the suburban community and from 2.80×101 to 1.80×105 CFU/ml in the urban community. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes were observed at densities of 0-1.36×103 CFU/ml, 0-8.40×102 CFU/ml, and 0-6.80×102 CFU/ml, respectively at the suburban community’s WWTP. In the urban community, observed densities of culturable Vibrio were 0-2.80×102 CFU/ml (180 μm), 0-6.60×102 CFU/ml (60 μm), and 0-1.80×103 CFU/ml (20 μm). The abundance of free-living Vibrio species ranged from 0 to 1.0×102 and 1.0×103 CFU/ml in the suburban and urban communities’ WWTPs, respectively. Molecular confirmation of the presumptive Vibrio isolates revealed the presence of V. fluvialis (41.38%), V. vulnificus (34.48%), and V. parahaemolyticus (24.14%) in the suburban community effluents. In the urban community molecular confirmation revealed that the same species were present at slightly different percentages, V. fluvialis (40%), V. vulnificus (36%), and V. parahaemolyticus (24%). There was no significant correlation between Vibrio abundance and season, either as free-living or planktonassociated entities, but Vibrio species abundance was positively correlated with temperature (r=0.565; p<0.01), salinity, and dissolved oxygen (p<0.05). Turbidity and pH showed significant seasonal variation (p<0.05) across the seasons in both locations. This study underscores the potential of WWTPs to be sources of Vibrio pathogens in the watershed of suburban and urban communities in South Africa.

Journal Article

Oceanicoccus sagamiensis gen. nov., sp. nov., a Gammaproteobacterium Isolated from Sea Water of Sagami Bay in Japan: Sanghwa Park , Kazuhiro Kogure , Akira Yokota; J. Microbiol. 2011;49(2):233-237. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0368-y

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Abstract: A gram-negative, motile, coccoid- and amorphous-shaped, non-pigmented chemoheterotrophic bacterium, designated strain PZ-5T, was isolated from sea water of Sagami Bay in Japan and subjected to a polyphasic taxonomic study. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the novel isolate could be affiliated with the class Gammaproteobacteria. Strain PZ-5T showed below 93.9% similarity with validly published bacteria and demonstrated the highest sequence similarity to Dasania marina KOPRI 20902T (93.9%). Strain PZ-5T formed a monophyletic group with D. marina KOPRI 20902T. The DNA G+C content of strain PZ-5T was 49.8 mol%. The major isoprenoid quinone was Q-8 and redominant cellular fatty acids were C15:0 ISO 2OH (19%), C16:1 ω7c (17.4%), C17:1 ω8c (16.2%), C11:0 3OH (7.5%), and C15:1 ω8c (6.5%). Based on evidence from a polyphasic taxonomical study, it was concluded that the strain should be classified as representing a new genus and species of the class Gammaproteobacteria, for which the name Oceanicoccus sagamiensis gen. nov., sp. nov., (type strain PZ-5T =NBRC 107125T =KCTC 23278T) is proposed.

Research Support, Non-U.S. Gov'ts

Sphingomonas jejuensis sp. nov., Isolated from Marine Sponge Hymeniacidon flavia: Sanghwa Park , Akira Yokota , Takashi Itoh , Jin-Sook Park; J. Microbiol. 2011;49(2):238-242. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0500-z

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Abstract: A Gram-negative, non-motile, rod shaped, and orange-pigmented chemoheterotrophic bacterium, strain MS-31T was isolated from the marine sponge Hymeniacidon flavia, collected from near Jeju Island, Korea. The Strain MS-31T was subjected to a polyphasic taxonomic study. The phylogenetic analysis based on the 16S rRNA gene sequences revealed that the novel isolate could be affiliated within the genus Sphingomonas. The strain MS-31T showed 95.6% of 16S rRNA gene sequence similarity with the most closely related species Sphingomonas koreensis JSS26T. The DNA G+C content of the strain MS-31T was 69.4 mol%. The major isoprenoid quinone was ubiqunone 10 and predominant cellular fatty acids were summed feature 7 (comprising C18:1 ω7c, C18:1 ω9t and/or C18:1 ω12t, 39.7%), C16:0 (16.3%), C14:0 2OH (15.9%) and summed feature 3 (comprising C16:1 ω7c and/or C15:0 iso 2OH, 11.7%). The polar lipids were sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and unidentified glycolipid. Based on the evidence from the polyphasic taxonomic study, the strain should be classified as a new species of the genus Sphingomonas. As a result, the name Sphingomonas jejuensis sp. nov. (type strain MS-31T =KCTC 23321T =NBRC 107775T) is proposed.

Acinetobacter baumannii Biofilms: Variations Among Strains and Correlations with Other Cell Properties: Christin N. McQueary , Luis A. Actis; J. Microbiol. 2011;49(2):243-250. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0343-7

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62 Citations

Abstract: Acinetobacter baumannii is an opportunistic pathogen that causes serious infections in humans by colonizing and persisting on surfaces normally found in hospital settings. The capacity of this pathogen to persist in these settings could be due to its ability to form biofilms on inanimate surfaces. This report shows that although the ATCC 19606T type strain and 8 different clinical isolates form biofilms, there are significant variations in the cell density and microscopic structures of these cell aggregates, with 3 of the isolates forming pellicles floating on the surface of stagnant broth cultures. PCR indicated that, like ATCC 19606T, all 8 clinical isolates harbor all the genetic components of the CsuA/BABCDE chaperone-usher pili assembly system, which is needed for biofilm formation on plastic. Pili detection in cells of all strains examined supports the presence and function of a pilus assembly system. However, only one of them produced the putative ATCC 19606T CsuA/B pilin subunit protein. Hydrophobicity tests and motility assays also showed significant variations among all tested strains and did not result in direct correlations between the biofilm phenotype and cell properties that could affect biofilm formation on abiotic surfaces. This lack of correlation among these 3 phenotypes may reflect some of the variations already reported with this pathogen, which may pose a challenge in the treatment of the infections this pathogen causes in humans using biofilm formation on abiotic surfaces as a target.

Identification of S-Nitrosylation of Proteins of Helicobacter pylori in Response to Nitric Oxide Stress: Wei Qu , Yabin Zhou , Yundong Sun , Ming Fang , Han Yu , Wenjuan Li , Zhifang Liu , Jiping Zeng , Chunyan Chen , Chengjiang Gao , Jihui Jia; J. Microbiol. 2011;49(2):251-256. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0262-7

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Abstract: Innate and adaptive immune responses are activated in humans when Helicobacter pylori invades the gastric mucosa. Nitric oxide (NO) and reactive nitrogen species are important immune effectors, which can exert their functions through oxidation and S-nitrosylation of proteins. S-nitrosoglutathione and sodium nitroprusside were used as NO donors and H. pylori cells were incubated with these compounds to analyze the inhibitory effect of NO. The suppressing effect of NO on H. pylori has been shown in vitro. Furthermore, the proteins modified by S-nitrosylation in H. pylori were identified through the biotin switch method in association with matrix-assisted laser desorption ionization/time-of-flight tandem mass spectrometry (MALDITOF- MS/MS). Five S-nitrosylated proteins identified were a chaperone and heat-shock protein (GroEL), alkyl hydroperoxide reductase (TsaA), urease alpha subunit (UreA), HP0721, and HP0129. Importantly, S-nitrosylation of TsaA and UreA were confirmed using purified recombinant proteins. Considering the importance of these enzymes in antioxidant defenses, adherence, and colonization, NO may exert its antibacterial actions by targeting enzymes through S-nitrosylation. Identification of protein S-nitrosylation may contribute to an understanding of the antibacterial actions of NO. Our findings provide an insight into potential targets for the development of novel therapeutic agents against H. pylori infection.

A Thermostable Phytase from Neosartorya spinosa BCC 41923 and Its Expression in Pichia pastoris: Patcharaporn Pandee , Pijug Summpunn , Suthep Wiyakrutta , Duangnate Isarangkul , Vithaya Meevootisom; J. Microbiol. 2011;49(2):257-264. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0369-x

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19 Citations

Abstract: A phytase gene was cloned from Neosartorya spinosa BCC 41923. The gene was 1,455 bp in size, and the mature protein contained a polypeptide of 439 amino acids. The deduced amino acid sequence contains the consensus motif (RHGXRXP) which is conserved among phytases and acid phosphatases. Five possible disulfide bonds and seven potential N-glycosylation sites have been predicted. The gene was expressed in Pichia pastoris KM71 as an extracellular enzyme. The purified enzyme had specific activity of 30.95 U/mg at 37°C and 38.62 U/mg at 42°C. Molecular weight of the deglycosylated recombinant phytase, determined by SDS-PAGE, was approximately 52 kDa. The optimum pH and temperature for activity were pH 5.5 and 50°C. The residual phytase activity remained over 80% of initial activity after the enzyme was stored in pH 3.0 to 7.0 for 1 h, and at 60% of initial activity after heating at 90°C for 20 min. The enzyme exhibited broad substrate specificity, with phytic acid as the most preferred substrate. Its Km and Vmax for sodium phytate were 1.39 mM and 434.78 U/mg, respectively. The enzyme was highly resistant to most metal ions tested, including Fe2+, Fe3+, and Al3+. When incubated with pepsin at a pepsin/phytase ratio of 0.02 (U/U) at 37°C for 2 h, 92% of its initial activity was retained. However, the enzyme was very sensitive to trypsin, as 5% of its initial activity was recovered after treating with trypsin at a trypsin/phytase ratio of 0.01 (U/U).

Research Support, U.S. Gov't, Non-P.H.S.

Transcriptional Control of Genes Involved in Yeast Phospholipid Biosynthesis: Roshini Wimalarathna , Chen-Han Tsai , Chang-Hui Shen; J. Microbiol. 2011;49(2):265-273. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-1130-1

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Abstract: Phospholipid biosynthetic genes encode enzymes responsible for phospholipid biosynthesis. They are coordinately regulated by the availability of phospholipid precursors through the inositol-sensitive upstream activating sequence (UASINO). However, not all phospholipid genes are UASINO-containing genes and not all UASINO-containing genes have the same response to the phospholipid precursors. Therefore, the transcriptional regulation of phospholipid genes in response to the availability of phospholipid precursors is still unclear. Here, 22 out of 47 phospholipid biosynthetic genes were identified as UASINO-containing genes, including EKI1, EPT1, INM1, IPK2, KCS1, PAH1, and PIK1 which have never been reported before. We also showed, using qRTPCR technique, that 12 UASINO-containing genes are down-regulated by 100 μM inositol in the wild type cells and up-regulated by 100 μM inositol in the ino2Δ cells. Therefore, it is possible that these genes are transcriptionally regulated by the UASINO through the negative response of Ino2p to inositol. One other UASINO-containing gene might be regulated by the positive response of Ino2p to 100 μM inositol. Surprisingly, we found 9 UASINO-containing genes are not dependent on the response of Ino2p to 100 μM inositol, indicating that they may be regulated by other pathway. Furthermore, we identified 9 and 3 non-UASINO-containing genes that are possibly regulated by the negative and positive response of Ino2p to 100 μM inositol, respectively. Therefore, these observations provide insight into the understanding of the co-regulated phospholipid biosynthetic genes expression.

Research Support, Non-U.S. Gov't

Genome Sequence Analysis of H5N1 Influenza A Virus Isolated from a Vietnamese in 2007: Dieu Linh Tran , Kangmo Kim , Jae Yoo Choi , Hyun Dong Paik , Si-Woo Choi , Jin Yeul Ma , Sung-Soon Kim , Sung Joon Ahn , Young Bong Kim; J. Microbiol. 2011;49(2):274-279. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0311-2

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Abstract: Highly pathogenic H5N1 avian influenza A virus (AIV) crossed the species barrier and caused a number of deaths in humans in Vietnam and 14 other countries. Since the last report of human H5N1 infection in November 2005, the first documented H5N1 human infection was reported in June 2007 in Vietnam and was followed by 7 more cases, including 5 fatalities. In this study, we isolated and analyzed the full length of the H5N1 genome from a sample from the first patient in 2007. Phylogenetic analysis of eight genomic segments of the H5N1 virus strain (A/Vietnam/HN/2007, VNH07) revealed that this strain appears to be of genotype V and contains the HA gene, which is classified into clade 2.3.4. The deduced amino acid sequence of the HA protein has a typical affinity sequence for α2,3 linkage (SAα2,3-Gal) receptors and typical multibasic cleavage sequences. Compared with other H5N1 isolates, VNH07 showed that the possible reassortments for the NA and NP segments occurred between A/goose/Guangxi/3017/2005-like isolates (2.3.2) and A/human/Zhejiang/16/2006-like isolates (2.3.4).

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