Discovery and Genomic Characterization of a Novel Ovine Partetravirus and a New Genotype of Bovine Partetravirus

Partetravirus is a recently described group of animal parvoviruses which include the human partetravirus, bovine partetravirus and porcine partetravirus (previously known as human parvovirus 4, bovine hokovirus and porcine hokovirus respectively). In this report, we describe the discovery and genomic characterization of partetraviruses in bovine and ovine samples from China. These partetraviruses were detected by PCR in 1.8% of bovine liver samples, 66.7% of ovine liver samples and 71.4% of ovine spleen samples. One of the bovine partetraviruses detected in the present samples is phylogenetically distinct from previously reported bovine partetraviruses and likely represents a novel genotype. The ovine partetravirus is a novel partetravirus and phylogenetically most related to the bovine partetraviruses. The genome organization is conserved amongst these viruses, including the presence of a putative transmembrane protein encoded by an overlapping reading frame in ORF2. Results from the present study provide further support to the classification of partetraviruses as a separate genus in Parvovirinae

Effect of antibiotics on the immune response induced by live-attenuated Salmonella typhi

published_or_final_versionMicrobiologyMasterMaster of Philosoph

Complete Genome Sequence of Staphylococcus lugdunensis Strain HKU09-01▿

Staphylococcus lugdunensis is a member of the coagulase-negative staphylococci and commonly found as part of the human skin flora. It is a significant cause of catheter-related bacteremia and also causes serious infections like native valve endocarditis in previously healthy individuals. We report the complete genome sequence of this medically important bacterium

Identification of Mycobacterium neoaurum Isolated from a Neutropenic Patient with Catheter-Related Bacteremia by 16S rRNA Sequencing

A rapidly growing pigmented mycobacterial strain with an ambiguous biochemical profile was isolated from the blood culture taken through the Hickman catheter of a 9-year-old girl with acute lymphoblastic leukemia. Whole-cell fatty acid analysis showed that the best match profile was that of Mycobacterium aurum, but the similarity index was only 0.217, meaning that there were no good matches between the isolate and the organisms in the database of the Microbial Identification System. The 16S rRNA gene of the mycobacterial strain was amplified, agarose gel purified, and sequenced. There were 44 base differences between the gene sequence of the isolate and that of M. aurum but only one base difference between the sequence of the isolate and that of Mycobacterium neoaurum, showing that the isolate was indeed a strain of M. neoaurum by using this “gold standard.” This represents the first case of M. neoaurum infection documented by 16S rRNA sequencing

Complete Genome Sequence of the Veterinary Pathogen Staphylococcus pseudintermedius Strain HKU10-03, Isolated in a Case of Canine Pyoderma▿

Staphylococcus pseudintermedius is a member of the coagulase-positive staphylococci and is the commonest cause of canine pyoderma. We report the first genome sequence of S. pseudintermedius, which shows the presence of numerous virulence factors akin to those of the related human pathogen Staphylococcus aureus

Clinical and virological factors associated with viremia in pandemic influenza A/H1N1/2009 virus infection.

BACKGROUND: Positive detection of viral RNA in blood and other non-respiratory specimens occurs in severe human influenza A/H5N1 viral infection but is not known to occur commonly in seasonal human influenza infection. Recently, viral RNA was detected in the blood of patients suffering from severe pandemic influenza A/H1N1/2009 viral infection, although the significance of viremia had not been previously studied. Our study aims to explore the clinical and virological factors associated with pandemic influenza A/H1N1/2009 viremia and to determine its clinical significance. METHODOLOGY/PRINCIPAL FINDINGS: Clinical data of patients admitted to hospitals in Hong Kong between May 2009 and April 2010 and tested positive for pandemic influenza A/H1N1/2009 was collected. Viral RNA was detected by reverse-transcription polymerase chain reactions (RT-PCR) targeting the matrix (M) and HA genes of pandemic influenza A/H1N1/2009 virus from the following specimens: nasopharyngeal aspirate (NPA), endotracheal aspirate (ETA), blood, stool and rectal swab. Stool and/ or rectal swab was obtained only if the patient complained of any gastrointestinal symptoms. A total of 139 patients were included in the study, with viral RNA being detected in the blood of 14 patients by RT-PCR. The occurrence of viremia was strongly associated with a severe clinical presentation and a higher mortality rate, although the latter association was not statistically significant. D222G/N quasispecies were observed in 90% of the blood samples. CONCLUSION: Presence of pandemic influenza A/H1N1/2009 viremia is an indicator of disease severity and strongly associated with D222G/N mutation in the viral hemagglutinin protein

Comparative Analysis of 22 Coronavirus HKU1 Genomes Reveals a Novel Genotype and Evidence of Natural Recombination in Coronavirus HKU1

We sequenced and compared the complete genomes of 22 strains of coronavirus HKU1 (CoV HKU1) obtained from nasopharyngeal aspirates of patients with respiratory tract infections over a 2-year period. Phylogenetic analysis of 24 putative proteins and polypeptides showed that the 22 CoV HKU1 strains fell into three clusters (genotype A, 13 strains; genotype B, 3 strains and genotype C, 6 strains). However, different phylogenetic relationships among the three clusters were observed in different regions of their genomes. From nsp4 to nsp6, the genotype A strains were clustered with the genotype B strains. For nsp7 and nsp8 and from nsp10 to nsp16, the genotype A strains were clustered with the genotype C strains. From hemagglutinin esterase (HE) to nucleocapsid (N), the genotype B strains were clustered closely with the genotype C strains. Bootscan analysis showed possible recombination between genotypes B and C from nucleotide positions 11500 to 13000, corresponding to the nsp6-nsp7 junction, giving rise to genotype A, and between genotypes A and B from nucleotide positions 21500 to 22500, corresponding to the nsp16-HE junction, giving rise to genotype C. Multiple alignments further narrowed the sites of crossover to a 143-bp region between nucleotide positions 11750 and 11892 and a 29-bp region between nucleotide positions 21502 and 21530. Genome analysis also revealed various numbers of tandem copies of a perfect 30-base acidic tandem repeat (ATR) which encodes NDDEDVVTGD and various numbers and sequences of imperfect repeats in the N terminus of nsp3 inside the acidic domain upstream of papain-like protease 1 among the 22 genomes. All 10 CoV HKU1 strains with incomplete imperfect repeats (1.4 and 4.4) belonged to genotype A. The present study represents the first evidence for natural recombination in coronavirus associated with human infection. Analysis of a single gene is not sufficient for the genotyping of CoV HKU1 strains but requires amplification and sequencing of at least two gene loci, one from nsp10 to nsp16 (e.g., pol or helicase) and another from HE to N (e.g., spike or N). Further studies will delineate whether the ATR is useful for the molecular typing of CoV HKU1

Cloning and Characterization of a Chromosomal Class C β-Lactamase and Its Regulatory Gene in Laribacter hongkongensis

Laribacter hongkongensis, a newly discovered bacterium recently shown to be associated with community-acquired gastroenteritis, is generally resistant to most β-lactams except the carbapenems. We describe the cloning and characterization of a novel chromosomal class C β-lactamase and its regulatory gene in L. hongkongensis. Two genes, ampC and ampR, were cloned by inserting restriction fragments of genomic DNA from L. hongkongensis strain HLHK5 into pBK-CMV to give the recombinant plasmid pBK-LHK-5. The ampR and ampC genes and their promoters were divergently oriented, with the ampR gene immediately upstream of the ampC gene and an intercistronic Lys-R motif, typical of inducible ampC-ampR regulatory systems. The deduced amino acid sequence of the cloned AmpC β-lactamase (pI 8.1) contained consensus motifs characteristic of class C β-lactamases but had identities no greater than 46% to known class C β-lactamases. The kinetic properties of this AmpC were also compatible with those of a class C β-lactamase. PCR of 20 clinical isolates of L. hongkongensis, including HLHK5, showed the presence of both ampC and ampR genes in all isolates. Southern hybridization suggested that the ampC gene of HLHK5 was chromosomally encoded. Subcloning experiments showed that the expression of the ampC gene of HLHK5 was regulated by its ampR gene, which acts as a repressor. The β-lactamase characterized from strain HLHK5 was named LHK-5 (gene, bla(LHK-5)) and represents the first example of AmpC β-lactamase in the β subdivision of proteobacteria