Nucleotide and Amino Acid Sequences in The PreM Region of A Japanese Encephalitis Virus Strain Isolated from A Pool of Aedes albopictus and Ae. butleri Mosquitoes Captured in Peninsula Malaysia in 1992

One strain of Japanese encephalitis (JE) virus isolated from a pool of Ae. albopictus and Ae. butleri in Peninsula Malaysia in 1992 was sequenced for its PreM gene region, by direct sequencing the product from reverse transcriptase polymerase chain reaction (RTPCR). The sequence in the length of 240 nucleotides (nt) and deduced amino acid (AA) sequence were compared with the published sequences for the various JE virus strains from different geographical regions. This virus strain, MaSAr39692, showed a close homology to the strains from epidemic areas such as Japan, China, Taiwan, Sri Lanka and India. The homology between MaSAr39692 and JaOArS982 strain, for which entire genome sequence was first determined, was 95.8%, with 10 nt and 3 AA sequence divergence

An Updated Loop-Mediated Isothermal Amplification Method for Rapid Diagnosis of H5N1 Avian Influenza Viruses

We designed a new set of primers for reverse transcriptase loop-mediated isothermal amplification (RTLAMP) to specifically amplify the HA gene of avian influenza viruses subtype H5N1. By testing nine H5N1 virus strains and 41 clinical samples collected in Northern Vietnam, we found that the new primers showed higher sensitivity and specificity than the previously published RT-LAMP primers and were comparable to the RT-PCR method currently recommended by WHO. These results suggest that our RT-LAMP assay may be a better choice as a diagnostic tool for current H5N1 influenza virus infection

Growth Patterns of Six Strains of Japanese Encephalitis Virus

Growths of 6 strains of Japanese encephalitis (JE) virus were studied in mosquito (C6/36) and baby hamster kidney (BHK21) cell cultures at 4 different temperatures. At 28℃, 3 strains (Nakayama, Beijing-1, JaOArS982) grew slower than other 3 strains (JaGAr01, JaOH0566, ML17) in C6/36 cells although their infectivity increased from 1 day after infection. On the other hand, infectivity of all strains increased from 2 days after infection in BHK21 cells. At 33 and 37℃, growth of JaOArS982 strain in C6/36 cells was shut-off 2 and 1 day after infection, respectively, while growths of all strains in BHK21 cells were shut-off 2 days after infection. At 39℃, growths of all strains were shut-off 1 day after infection in both cell lines, and infectivity of Nakayama strain showed little increase in C6/36 cells. The results indicated some host cell factor(s) regulating replication of JE virus, especially in C6/36

HEPATITIS C VIRUS AND ITS GENE STRUCTURE AND FUNCTION

Hepatitis C virus (HCV) is a member of the family Flaviviridae, and the principal cause of parenteral non A non B hepatitis. HCV is a single stranded, positive sense RNA virus whose genome contains a single open reading frame of about 10 kb in length which encodes a polyprotein of about 3000 amino acids. HCV is responsible for majority of the transfusion associated cases of hepatitis and a significant proportion of community-acquired hepatitis which leads to a range of clinical manifestations from an apparent carrier state to severe chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Cell-free translation and cell culture transient expression studies revealed that HCV genome initially transcribed as a polyprotein is processed by cellular and viral proteases to produce the putative viral structural and nonstructural proteins. The preliminary map of the gene order for HCV was established: 5\u27 untranslated region (UTR)-core (C)-envelope 1 (E1)-E2-nonstructural 2(NS2)-NS3-NS4A-NS4B-NS5A-NS5B-UTR3\u27. Nonstructural proteins, NS2, NS3 and NS5, are believed to be a component of viral coded enzymes. Mutations in hypervariable region 1 (HVR1) of the E2 protein was considered to be a possible mechanism of chronicity of HCV infection. HCV infection can be monitored either by serodiagnosis or by genodiagnosis. Interferon seems to be considered as the sole drug for HCV treatment until now. In the history of virology, HCV was the first example that was identified by molecular cloning of its genome from infectious materials

Clinical Manifestations and Treatment of Dengue Hemorrhagic Fever (DHF) by 13 Years Experience, More Than 10,000 Cases

Clinical manifestations and treatment on dengue hemorrhagic fever (DHF) were summarized based on 13 years experience of the first author at the Pediatric Department, Nakorn Phanom Provincial Hospital, Thailand. DHF is an acute febrile disease, characterized by hemoconcentration, thrombocytopenia, and coagulopathy. The underlying mechanism of increased vascular permeability, leads to hemoconcentration, hypovolemic shock, metabolic abnormalities, then disseminated intravascular coagulation (DIC), if not properly treated. Direct cause of death in DHF is either circulatory failure or massive hemorrhage. Therefore, DHF case management should be directed to correct determination of the stage and grade of the disease, and prescribe proper recipes, such as intravenous infusion and blood transfusion

A Single Amino Acid Substitution in the NS2A Protein of Japanese Encephalitis Virus Affects Virus Propagation In Vitro but Not In Vivo

We identified a unique amino acid of NS2A113, phenylalanine, that affects the efficient propagation of two Japanese encephalitis virus strains, JaTH160 and JaOArS982, in neuroblastoma Neuro-2a cells but not in cell lines of extraneural origin. This amino acid did not affect viral loads in the brain or survival curves in mice. These findings suggest that virus propagation in vitro may not reflect the level of virus neuroinvasiveness in vivo

In Vitro Difference between an Attenuated ML-17 and its Parental Virulent JaOH0566 Strain of Japanese Encephalitis Virus

Two Japanese encephalitis (JE) virus strains, namely a virulent JaOH0556 and an attenuated ML-17 derived from it were studied to investigate their in vitro phenotypic differences. When both strains were concentrated by polyethylene glycol (PEG) 6000 precipitation, infectivity of the ML-17 was recovered only 4.94% compared to 42.21% for the parental JaOH0566 strain, and the virion peak was very low for the ML-17 in contrast to a sharp peak for the JaOH0566 in sucrose density gradient centrifugation. When both strains were incubated with sucrose solutions, the ML-17 was slightly more labile than the JaOH0566 at high concentration of sucrose. These findings may indicate difference in the virion structure of both strains

Stability and Infectivity of SARS-CoV-2 and Viral RNA in Water, Commercial Beverages, and Bodily Fluids

The stability and infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in liquid samples are of great concern to virus transmission via common beverages and sewage water. Here, we investigated the stability of SARS-CoV-2 in 32 liquids including common beverages, bodily fluids, and commonly used viral transport media. Our results showed that the infectious virus could be recovered up to 77-days from common beverages including milk and water. Viral RNA could be detected at high levels in all samples up to 28-days, indicating that while viral RNA demonstrates higher stability than infectivity, viral RNA levels do not reflect the infectious capability of SARS-CoV-2. These results indicate that SARS-CoV-2 is highly stable in optimal conditions and a sufficient control measure is needed in reducing the risk of exposure and controlling and preventing future outbreaks

NS1’ Protein Expression in the JaOArS982 Strain of Japanese Encephalitis Virus Does Not Enhance Virulence in Mice

Using a mouse model, we previously demonstrated that subcutaneous infection with the JaTH160 strain of Japanese encephalitis virus (JEV) causes significantly higher virulence and stronger virus propagation in the brain compared with that of the JaOArS982 strain. We also showed that the JaTH160 strain, but not JaOArS982, expresses the NS1’ protein and that NS1’ enhances JEV production in avian cells and embryonated chicken eggs. In this study, we examined whether NS1’ expression affects virulence in mice infected with the JaOArS982 and JaTH160 strains using the corresponding recombinant viruses S982-IC and JaTH-IC. Expression of the NS1’ protein in S982-IC diminished the mortality in mice, whereas S982-IC viruses without NS1’ caused 40?60% mortality. However, the viral loads in the brains of these mice were not significantly different despite the dvariation in NS1’ expression. JaTH-IC viruses depleted of the NS1’ protein exhibited high mortality levels, similar to those of the virus expressing NS1’. Previous studies showed that the NS1’ protein plays a role in the enhanced virulence of the JEV SA14 strain in mice. However, our current data suggest that NS1’ protein expression in S982-IC reduces, rather than enhances, the mortality in mice. Thus, the effect of NS1’ on pathogenicity in vivo may vary among virus strains. Our data also suggest that the reduced mortality resulting from NS1’ expression in S982-IC is not simply due to viral replication in the brains. Further investigation is needed to uncover the mechanism by which NS1’ affects pathogenicity in JEV-infected animals