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  1. Leung AKC, Hon KL, Leong KF
    Hong Kong Med J, 2019 04;25(2):134-141.
    PMID: 30967519 DOI: 10.12809/hkmj187785
    Rubella is generally a mild and self-limited disease in children. During pregnancy, rubella can have potentially devastating effects on the developing fetus. Postnatal rubella is transmitted primarily by inhalation of virus-laden airborne droplets or direct contact with infected nasopharyngeal secretions. In susceptible pregnant women, the virus may cross the placenta and spread through the vascular system of the developing fetus. Postnatally acquired rubella typically begins with fever and lymphadenopathy, followed by an erythematous, maculopapular rash. The rash classically begins on the face, spreads cephalocaudally, becomes generalised within 24 hours, and disappears within 3 days. Maternal rubella, especially during early pregnancy, may lead to miscarriage, intrauterine fetal death, premature labour, intrauterine growth retardation, and congenital rubella syndrome. Cataracts, congenital heart defects, and sensorineural deafness are the classic triad of congenital rubella syndrome and they typically occur if the fetal infection occurs in the first 11 weeks of gestation. Laboratory confirmation of rubella virus infection can be based on a positive serological test for rubella-specific immunoglobulin M antibody; a four-fold or greater increase in rubella-specific immunoglobulin G titres between acute and convalescent sera; or detection of rubella virus RNA by reverse transcriptase-polymerase chain reaction. Treatment is mainly symptomatic. Universal childhood immunisation and vaccination of all susceptible patients with rubella vaccine to decrease circulation of the virus are cornerstones to prevention of rubella and, more importantly, congenital rubella syndrome.
  2. Leung AK, Hon KL, Leong KF, Sergi CM
    Hong Kong Med J, 2018 Oct;24(5):512-520.
    PMID: 30245481 DOI: 10.12809/hkmj187470
    Measles (rubeola) is a highly contagious vaccine-preventable disease caused by the measles virus-a virus of the Paramyxoviridae family. The illness typically begins with fever, runny nose, cough, and pathognomonic enanthem (Koplik spots) followed by a characteristic erythematous, maculopapular rash. The rash classically begins on the face and becomes more confluent as it spreads cephalocaudally. Laboratory confirmation of measles virus infection can be based on a positive serological test for measles-specific immunoglobulin M antibody, a four-fold or greater increase in measles-specific immunoglobulin G between acute and convalescent sera, isolation of measles virus in culture, or detection of measles virus ribonucleic acid by reverse transcriptase-polymerase chain reaction. Complications occur in 10% to 40% of patients, and treatment is mainly symptomatic. Bacterial superinfections, if present, should be properly treated with antibiotics. To eradicate measles, universal childhood immunisation and vaccination of all susceptible individuals with measles vaccine would be ideal. In developed countries, routine immunisation with measles-containing vaccine is recommended, with the first and second doses at ages 12 to 15 months and 4 to 6 years, respectively. The World Health Organization recommends that the first and second doses of measles-containing vaccine be given at ages 9 months and 15 to 18 months, respectively, in countries with high rates of measles transmission.
  3. Kasloff SB, Leung A, Pickering BS, Smith G, Moffat E, Collignon B, et al.
    Sci Rep, 2019 03 26;9(1):5230.
    PMID: 30914663 DOI: 10.1038/s41598-019-40476-y
    In 1998 an outbreak of fatal encephalitis among pig farm workers in Malaysia and Singapore led to the discovery of Nipah henipavirus (NiV), a novel paramyxovirus closely related to Hendra henipavirus with case fatality rates of nearly 40%. Following its initial emergence nearly annual outbreaks of NiV have occurred in Bangladesh with a different, NiV Bangladesh, genotype, where the role of pigs in its transmission remains unknown. The present study provides the first report on susceptibility of domestic pigs to NiV Bangladesh following experimental infection, characterizing acute and long-term phases of disease and pathogenesis. All pigs were successfully infected with NiV Bangladesh following oronasal inoculation, with viral shedding confirmed by a novel genotype-specific qRT-PCR in oral, nasal and rectal excretions and dissemination from the upper respiratory tract to the brain, lungs, and associated lymphatic tissues. Unlike previous NiV Malaysia findings in pigs, clinical signs were absent, viremia was undetectable throughout the study, and only low level neutralizing antibody titers were measured by 28/29 days post-NiV-B infection. Results obtained highlight the need for continued and enhanced NiV surveillance in pigs in endemic and at-risk regions, and raise questions regarding applicability of current serological assays to detect animals with previous NiV-B exposure.
  4. Griffin BD, Leung A, Chan M, Warner BM, Ranadheera C, Tierney K, et al.
    Sci Rep, 2019 08 01;9(1):11171.
    PMID: 31371748 DOI: 10.1038/s41598-019-47549-y
    Nipah virus (NiV) has emerged as a highly lethal zoonotic paramyxovirus that is capable of causing a febrile encephalitis and/or respiratory disease in humans for which no vaccines or licensed treatments are currently available. There are two genetically and geographically distinct lineages of NiV: NiV-Malaysia (NiV-M), the strain that caused the initial outbreak in Malaysia, and NiV-Bangladesh (NiV-B), the strain that has been implicated in subsequent outbreaks in India and Bangladesh. NiV-B appears to be both more lethal and have a greater propensity for person-to-person transmission than NiV-M. Here we describe the generation and characterization of stable RNA polymerase II-driven infectious cDNA clones of NiV-M and NiV-B. In vitro, reverse genetics-derived NiV-M and NiV-B were indistinguishable from a wildtype isolate of NiV-M, and both viruses were pathogenic in the Syrian hamster model of NiV infection. We also describe recombinant NiV-M and NiV-B with enhanced green fluorescent protein (EGFP) inserted between the G and L genes that enable rapid and sensitive detection of NiV infection in vitro. This panel of molecular clones will enable studies to investigate the virologic determinants of henipavirus pathogenesis, including the pathogenic differences between NiV-M and NiV-B, and the high-throughput screening of candidate therapeutics.
  5. Papadaki V, Asada K, Watson JK, Tamura T, Leung A, Hopkins J, et al.
    Cancers (Basel), 2020 Nov 13;12(11).
    PMID: 33202923 DOI: 10.3390/cancers12113362
    Osteomodulin (OMD) and proline/arginine-rich end leucine repeat protein (PRELP) are secreted extracellular matrix proteins belonging to the small leucine-rich proteoglycans family. We found that OMD and PRELP were specifically expressed in umbrella cells in bladder epithelia, and their expression levels were dramatically downregulated in all bladder cancers from very early stages and various epithelial cancers. Our in vitro studies including gene expression profiling using bladder cancer cell lines revealed that OMD or PRELP application suppressed the cancer progression by inhibiting TGF-β and EGF pathways, which reversed epithelial-mesenchymal transition (EMT), activated cell-cell adhesion, and inhibited various oncogenic pathways. Furthermore, the overexpression of OMD in bladder cancer cells strongly inhibited the anchorage-independent growth and tumorigenicity in mouse xenograft studies. On the other hand, we found that in the bladder epithelia, the knockout mice of OMD and/or PRELP gene caused partial EMT and a loss of tight junctions of the umbrella cells and resulted in formation of a bladder carcinoma in situ-like structure by spontaneous breakdowns of the umbrella cell layer. Furthermore, the ontological analysis of the expression profiling of an OMD knockout mouse bladder demonstrated very high similarity with those obtained from human bladder cancers. Our data indicate that OMD and PRELP are endogenous inhibitors of cancer initiation and progression by controlling EMT. OMD and/or PRELP may have potential for the treatment of bladder cancer.
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