Identification of a novel feline picornavirus from the domestic cat.

While picornaviruses are known to infect different animals, their existence in the domestic cat was unknown. We describe the discovery of a novel feline picornavirus (FePV) from stray cats in Hong Kong. From samples from 662 cats, FePV was detected in fecal samples from 14 cats and urine samples from 2 cats by reverse transcription-PCR (RT-PCR).

Complete genome sequence of a coxsackievirus A22 strain in Hong Kong reveals a natural intratypic recombination event.

Coxsackievirus A22 (CVA22) belongs to the species human enterovirus C in the Picornaviridae family. We report the first complete genome sequence of CVA22 with natural intratypic recombination between CVA22 prototype strain Chulman and CVA22 strain ban99-10427, identified in the stool of a patient in Hong Kong.

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.

High incidence of severe influenza among individuals over 50 years of age.

Age-specific epidemiological data on asymptomatic, symptomatic, and severe infections are essential for public health policies on combating influenza. In this study, we incorporated data on microbiologically confirmed infections and seroprevalence to comprehensively describe the epidemiology of pandemic H1N1 2009 influenza. Seroprevalence was determined from 1,795 random serum samples collected in our hospital in January 2007 (before the first wave of the pandemic) and March 2010 (after the second wave).

Molecular epidemiology of human coronavirus OC43 reveals evolution of different genotypes over time and recent emergence of a novel genotype due to natural recombination.

Although human coronavirus OC43-OC43 (HCoV-OC43) is the coronavirus most commonly associated with human infections, little is known about its molecular epidemiology and evolution. We conducted a molecular epidemiology study to investigate different genotypes and potential recombination in HCoV-OC43. Twenty-nine HCoV-OC43 strains from nasopharyngeal aspirates, collected from 2004 to 2011, were subjected to RNA-dependent RNA polymerase (RdRp), spike, and nucleocapsid gene analysis.

Age-matched comparison of children hospitalized for 2009 pandemic H1N1 influenza with those hospitalized for seasonal H1N1 and H3N2.

Background: A wide spectrum of clinical manifestation ranging from deaths to a mild course of disease has been reported in children infected with the 2009 pandemic H1N1 (pH1N1) influenza.

Methodology/major Findings: We conducted an age-matched control study comparing children hospitalized for pH1N1 with historic controls infected with seasonal H1N1 and H3N2 influenza to correct for the effect of age on disease susceptibility and clinical manifestations. We also compared children with pH1N1 to children concurrently admitted for seasonal influenza during the pandemic period to adjust for differences in health-seeking behavior during the pandemic or other potential bias associated with historic controls.

Complete genome analysis of three novel picornaviruses from diverse bat species.

Although bats are important reservoirs of diverse viruses that can cause human epidemics, little is known about the presence of picornaviruses in these flying mammals. Among 1,108 bats of 18 species studied, three novel picornaviruses (groups 1, 2, and 3) were identified from alimentary specimens of 12 bats from five species and four genera. Two complete genomes, each from the three picornaviruses, were sequenced.

Co-existence of multiple strains of two novel porcine bocaviruses in the same pig, a previously undescribed phenomenon in members of the family Parvoviridae, and evidence for inter- and intra-host genetic diversity and recombination.

Despite the recent discovery of novel bocaviruses from porcine samples, their genetic evolution and diversity are poorly understood. This study reports the identification and complete genome characterization of two novel parvoviruses, porcine bocavirus 3 (PBoV3) and porcine bocavirus 4 (PBoV4), from various porcine tissues/samples, displaying marked intra- and inter-host genetic diversity, with recombination events. Bocaviruses were detected by PCR among 16.

Comparative evaluation of a point-of-care immunochromatographic test SNAP 4Dx with molecular detection tests for vector-borne canine pathogens in Hong Kong.

There are no comprehensive studies on the performance of commonly used point-of-care diagnostic enzyme immunoassay for common arthropod-borne canine pathogens. A comparative evaluation of an immunochromatographic test for these infections with a comprehensive polymerase chain reaction (PCR) test panel was performed on 100 pet dogs and 100 stray dogs without obvious clinical symptoms. Of the 162 positive test results from both immunochromatographic test and PCR, there was 85.

Rapid genotyping of swine influenza viruses.

The emergence of pandemic (H1N1) 2009 virus highlighted the need for enhanced surveillance of swine influenza viruses. We used real-time reverse-transcription PCR-based genotyping and found that this rapid and simple genotyping method may identify reassortants derived from viruses of Eurasian avian-like, triple reassortant-like, and pandemic (H1N1) 2009 virus lineages.

Is respiratory viral infection really an important trigger of asthma exacerbations in children?

We performed a prospective cohort study from September 2003 to December 2004 to delineate attributing the effect of different respiratory viral infections including newly discovered ones to asthma exacerbations in children in Hong Kong. One hundred and fourteen children aged 6-14 years with chronic stable asthma and on regular inhaled steroid were monitored for respiratory symptoms over a full calendar year from recruitment. They would attend the study clinic if peak expiratory flow rate decreased to below 80% of their baselines, if they met a predefined symptom score, or if parents subjectively felt them developing a cold.

Validation of statistical models for estimating hospitalization associated with influenza and other respiratory viruses.

Background: Reliable estimates of disease burden associated with respiratory viruses are keys to deployment of preventive strategies such as vaccination and resource allocation. Such estimates are particularly needed in tropical and subtropical regions where some methods commonly used in temperate regions are not applicable. While a number of alternative approaches to assess the influenza associated disease burden have been recently reported, none of these models have been validated with virologically confirmed data.

Differences in antibody responses of individuals with natural infection and those vaccinated against pandemic H1N1 2009 influenza.

The differential antibody response measured by the commonly used hemagglutination inhibition (HI) and microneutralization (MN) assays in patients with natural infection and vaccination has not been fully assessed. HI and conventional MN (CMN) assays were performed on sera from 651 patients with natural infection by pandemic H1N1 2009 influenza virus and on sera from 567 recipients of the corresponding vaccine. Surprisingly, the overall seroprotection rates determined by CMN and HI assays in vaccine recipients were only 44.

Convalescent plasma treatment reduced mortality in patients with severe pandemic influenza A (H1N1) 2009 virus infection.

Background: Experience from treating patients with Spanish influenza and influenza A(H5N1) suggested that convalescent plasma therapy might be beneficial. However, its efficacy in patients with severe pandemic influenza A(H1N1) 2009 virus (H1N1 2009) infection remained unknown.

Methods: During the period from 1 September 2009 through 30 June 2010, we conducted a prospective cohort study by recruiting patients aged ≥ 18 years with severe H1N1 2009 infection requiring intensive care.

The lower serum immunoglobulin G2 level in severe cases than in mild cases of pandemic H1N1 2009 influenza is associated with cytokine dysregulation.

The majority of patients with pandemic influenza H1N1 2009 had mild illness, but some, including those with no risk factors for severe disease, may succumb to this infection. Besides viral factors such as the D222/225G substitution of the hemagglutinin, host factors such as IgG2 subclass deficiency recently was reported to be associated with severe disease in a cohort of Australian patients besides other known risk factors, including underlying chronic illness, extremes of age, and pregnancy. We conducted a case-control study of 38 Asian patients with respiratory failure due to severe pandemic influenza and compared the results to those for 36 mild cases.

Protective efficacy of seasonal influenza vaccination against seasonal and pandemic influenza virus infection during 2009 in Hong Kong.

Background: The relationship between seasonal influenza vaccine and susceptibility to 2009 pandemic A/H1N1 virus infection is not fully understood.

Methods: One child 6-15 years of age from each of 119 households was randomized to receive 1 dose of inactivated trivalent seasonal influenza vaccine (TIV) or saline placebo in November 2008. Serum samples were collected from study subjects and their household contacts before and 1 month after vaccination (December 2008), after winter (April 2009) and summer influenza (September-October 2009) seasons.

Wild type and mutant 2009 pandemic influenza A (H1N1) viruses cause more severe disease and higher mortality in pregnant BALB/c mice.

Background: Pregnant women infected by the pandemic influenza A (H1N1) 2009 virus had more severe disease and higher mortality but its pathogenesis is still unclear.

Principal Findings: We showed that higher mortality, more severe pneumonitis, higher pulmonary viral load, lower peripheral blood T lymphocytes and antibody responses, higher levels of proinflammatory cytokines and chemokines, and worse fetal development occurred in pregnant mice than non-pregnant controls infected by either wild type (clinical isolate) or mouse-adapted mutant virus with D222G substitution in hemagglutinin. These disease-associated changes and the lower respiratory tract involvement were worse in pregnant mice challenged by mutant virus.

Coexistence of different genotypes in the same bat and serological characterization of Rousettus bat coronavirus HKU9 belonging to a novel Betacoronavirus subgroup.

Rousettus bat coronavirus HKU9 (Ro-BatCoV HKU9), a recently identified coronavirus of novel Betacoronavirus subgroup D, from Leschenault's rousette, was previously found to display marked sequence polymorphism among genomes of four strains. Among 10 bats with complete RNA-dependent RNA polymerase (RdRp), spike (S), and nucleocapsid (N) genes sequenced, three and two sequence clades for all three genes were codetected in two and five bats, respectively, suggesting the coexistence of two or three distinct genotypes of Ro-BatCoV HKU9 in the same bat. Complete genome sequencing of the distinct genotypes from two bats, using degenerate/genome-specific primers with overlapping sequences confirmed by specific PCR, supported the coexistence of at least two distinct genomes in each bat.

Concurrent comparison of epidemiology, clinical presentation and outcome between adult patients suffering from the pandemic influenza A (H1N1) 2009 virus and the seasonal influenza A virus infection.

Purpose Of Study: The demographics, clinical features and outcome of patients with pandemic influenza A (H1N1) 2009 infection were compared with a concurrent cohort of patients with seasonal influenza A infection.

Study Design: The clinical and microbiological data of hospitalised adult patients admitted between 29 June and 28 October 2009, with pandemic A (H1N1) 2009 or seasonal influenza A infection, were analysed.

Results: A total of 186 patients including 69 pandemic A (H1N1) and 117 seasonal influenza were analysed.

D225G mutation in hemagglutinin of pandemic influenza H1N1 (2009) virus enhances virulence in mice.

Although the majority of infections by the pandemic influenza H1N1 (2009) virus is mild, a higher mortality occurs in young adults with no risk factors for complications. Some of these severe cases were infected by the virus with an aspartate to glycine substitution at 225 position (D225G, H3 numbering) in the hemagglutinin (HA). Previous studies with the highly virulent 1918 pandemic H1N1 virus suggested that such substitution was associated with a dual binding specificity of the virus for both alpha2,3- and alpha2,6-linked sialic acid receptors on host cells.

Virologically confirmed population-based burden of hospitalization caused by respiratory syncytial virus, adenovirus, and parainfluenza viruses in children in Hong Kong.

Objectives: To determine virologically confirmed hospitalization rates associated with respiratory syncytial virus (RSV), adenovirus, and parainfluenza viruses in Hong Kong children.

Methods: All patients <18 years of age living on Hong Kong Island (within Hong Kong SAR) admitted for a febrile acute respiratory infection to 1 of the 2 public hospitals on 1 fixed day of the week between October 2003 and September 2006 were prospectively recruited. Hong Kong Island has a known population denominator and these 2 hospitals managed 72.

Effect of clinical and virological parameters on the level of neutralizing antibody against pandemic influenza A virus H1N1 2009.

Background: Little is known about the antibody response in natural infection by the novel 2009 influenza A (H1N1) virus and its relationship with clinical and virological parameters. The relative lack of background neutralizing antibody against this novel virus provides a unique opportunity for understanding this issue.

Methods: Case patients presenting with influenza-like illness who were positive for the pandemic H1 gene by reverse transcription polymerase chain reaction were identified.

Rapid detection of reassortment of pandemic H1N1/2009 influenza virus.

Background: Influenza viruses can generate novel reassortants in coinfected cells. The global circulation and occasional introductions of pandemic H1N1/2009 virus in humans and in pigs, respectively, may allow this virus to reassort with other influenza viruses. These possible reassortment events might alter virulence and/or transmissibility of the new reassortants.

Comparative epidemiology of pandemic and seasonal influenza A in households.

Background: There are few data on the comparative epidemiology and virology of the pandemic 2009 influenza A (H1N1) virus and cocirculating seasonal influenza A viruses in community settings.

Methods: We recruited 348 index patients with acute respiratory illness from 14 outpatient clinics in Hong Kong in July and August 2009. We then prospectively followed household members of 99 patients who tested positive for influenza A virus on rapid diagnostic testing.

Comparative analysis of six genome sequences of three novel picornaviruses, turdiviruses 1, 2 and 3, in dead wild birds, and proposal of two novel genera, Orthoturdivirus and Paraturdivirus, in the family Picornaviridae.

In this territory-wide molecular epidemiology study of picornaviruses, involving 6765 dead wild birds from 201 species in 50 families over a 12 month period, three novel picornaviruses, turdiviruses 1, 2 and 3 (TV1, TV2 and TV3), were identified from birds of different genera in the family Turdidae. In contrast to many other viruses in birds of the family Turdidae or viruses of the family Picornaviridae, TV1, TV2 and TV3 were found exclusively in the autumn and winter months. Two genomes each of TV1, TV2 and TV3 were sequenced.