Search PubMed⌕ Search

Biomedical subjects

Mary Jane Cardosa

Publications and source records attributed to Mary Jane Cardosa.

11 recordsLinked to original sources
PubMed2006

Of cascades and perfect storms: the immunopathogenesis of dengue haemorrhagic fever-dengue shock syndrome (DHF/DSS).

The past four decades has witnessed a consolidation of the original observations made in the 1970s that dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) have an immunological basis. Following reinfection with a dengue virus of different serotype, severe disease is linked to high levels of antibody-enhanced viral replication early in illness which is followed by a cascade of memory T-cell activation and a 'storm' of inflammatory cytokines and other chemical mediators. These compounds are released mainly from T cells, monocytes/macrophages and endothelial cells, and ultimately cause an increase in vascular permeability. The consolidation of the evidence has been largely due to several important prospective sero-epidemiological studies in areas endemic for DHF/DSS, which have shown that risk of severe disease is significantly higher in secondary dengue infections. These advances have underscored the fact that DHF/DSS pathogenesis is a complex, multifactorial process involving cocirculation of various dengue virus serotypes and the interplay of host and viral factors that influence disease severity. The continued search to define risk factors in susceptible populations must be combined with the new techniques of molecular virology and innovative approaches in vaccine design to achieve the ultimate objective of developing a safe and effective vaccine.

Antibodies, Viral↗
PubMed2006

Sentinel surveillance for human enterovirus 71 in Sarawak, Malaysia: lessons from the first 7 years.

BACKGROUND: A major outbreak of human enterovirus 71-associated hand, foot and mouth disease in Sarawak in 1997 marked the beginning of a series of outbreaks in the Asia Pacific region. Some of these outbreaks had unusually high numbers of fatalities and this generated much fear and anxiety in the region. METHODS: We established a sentinel surveillance programme for hand, foot and mouth disease in Sarawak, Malaysia, in March 1998, and the observations of the first 7 years are described here. Virus isolation, serotyping and genotyping were performed on throat, rectal, vesicle and other swabs. RESULTS: During this period Sarawak had two outbreaks of human enterovirus 71, in 2000 and 2003. The predominant strains circulating in the outbreaks of 1997, 2000 and 2003 were all from genogroup B, but the strains isolated during each outbreak were genetically distinct from each other. Human enterovirus 71 outbreaks occurred in a cyclical pattern every three years and Coxsackievirus A16 co-circulated with human enterovirus 71. Although vesicles were most likely to yield an isolate, this sample was not generally available from most cases and obtaining throat swabs was thus found to be the most efficient way to obtain virological information. CONCLUSION: Knowledge of the epidemiology of human enterovirus 71 transmission will allow public health personnel to predict when outbreaks might occur and to plan interventions in an effective manner in order to reduce the burden of disease.

Child↗
PubMed2006

Recombinant Newcastle Disease virus capsids displaying enterovirus 71 VP1 fragment induce a strong immune response in rabbits.

The complete VP1 protein of EV71 was truncated into six segments and fused to the C-terminal ends of full-length nucleocapsid protein (NPfl) and truncated NP (NPt; lacks 20% amino acid residues from its C-terminal end) of newcastle disease virus (NDV). Western blot analysis using anti-VP1 rabbit serum showed that the N-terminal region of the VP1 protein contains a major antigenic region. The recombinant proteins carrying the truncated VP1 protein, VP1(1-100), were expressed most efficiently in Escherichia coli as determined by Western blot analysis. Electron microscopic analysis of the purified recombinant protein, NPt-VP(1-100) revealed that it predominantly self-assembled into intact ring-like structures whereas NPfl-VP(1-100) recombinant proteins showed disrupted ring-like formations. Rabbits immunized with the purified NPt-VP(1-100) and NPfl-VP(1-100) exhibited a strong immune response against the complete VP1 protein. The antisera of these recombinant proteins also reacted positively with authentic enterovirus 71 and the closely related Coxsackievirus A16 when analyzed by an immunofluorescence assay suggesting their potential as immunological reagents for the detection of anti-enterovirus 71 antibodies in serum samples.

Animals↗
PubMed2005

Two dimensional VOPBA reveals laminin receptor (LAMR1) interaction with dengue virus serotypes 1, 2 and 3.

BACKGROUND: The search for the dengue virus receptor has generated many candidates often identified only by molecular mass. The wide host range of the viruses in vitro combined with multiple approaches to identifying the receptor(s) has led to the notion that many receptors or attachment proteins may be involved and that the different dengue virus serotypes may utilize different receptors on the same cells as well as on different cell types. RESULTS: In this study we used sequential extraction of PS Clone D cell monolayers with the detergent beta-octylglucopyranoside followed by sodium deoxycholate to prepare a cell membrane-rich fraction. We then used 2 dimensional (2D) gel electrophoresis to separate the membrane proteins and applied a modified virus overlay protein binding assay (VOPBA) to show that dengue virus serotypes 1, 2 and 3 all interact with the 37 kDa/67 kDa laminin receptor (LAMR1), a common non-integrin surface protein on many cell types. CONCLUSION: At least 3 of the 4 dengue serotypes interact with the 37 kDa/67 kDa laminin receptor, LAMR1, which may be a common player in dengue virus-cell surface interaction.

Animals↗
PubMed2004

Incorrect identification of recent Asian strains of Coxsackievirus A16 as human enterovirus 71: improved primers for the specific detection of human enterovirus 71 by RT PCR.

BACKGROUND: Human enterovirus 71 has emerged as an important pathogen in the Asia Pacific region and it is important to be able to make a rapid and specific diagnosis for outbreak control. Recent Asian strains of Coxsackievirus A16 have changes in the VP1 gene which causes mispriming of widely used primers for human enterovirus 71 specific identification. METHODS: Local strains of Coxsackievirus A16 were sequenced in the VP4 and VP1 genes and using sequence alignment tools, an improved set of primers were designed for specific identification of human enterovirus 71. These primers were evaluated against virus isolates as well as primary clinical specimens. RESULTS: A total of 218 virus strains were tested. All 39 human enterovirus 71 isolates were positive and none of the 38 Coxsackievirus A16, 127 other enteroviruses and 14 prototype flaviviruses and adenoviruses were positive when tested with the new primers. When aliquots of primary specimens known to have yielded human enterovirus 71 were retrospectively tested, we found that within 2 months of collection of the specimens, greater than 90% were positive but that the success rate diminished rapidly to 18% after 2 years storage. CONCLUSIONS: Our new primers will be useful in rapid diagnosis of human enterovirus 71 infection, and can also be used as a screening tool in surveillance programmes for early warning of human enterovirus 71 transmission.

Asian People↗
PubMed2003

Adenovirus type 21-associated acute flaccid paralysis during an outbreak of hand-foot-and-mouth disease in Sarawak, Malaysia.

We report the virological and clinical features of 8 children who presented with adenovirus-associated acute flaccid paralysis (AFP) during an epidemic of enterovirus type 71 (EV71)-associated hand-foot-and-mouth disease (HFMD) in Sarawak, Malaysia, in 1997. Neutralization tests and phylogenetic analysis revealed adenovirus type 21 (Ad21), although DNA restriction digests suggested that this virus was different from the prototype Ad21. Four children had upper-limb monoparesis, 2 had lower-limb monoparesis (one of whom had changes in the anterior spinal cord noted on magnetic resonance imaging), and 2 had flaccid paraparesis. At follow-up, 4 children were noted to have made full recoveries and 3 had residual flaccid weakness and wasting. Neurophysiological investigation revealed a mixture of axonal and demyelinating features in motor and sensory nerves, with denervation. These findings suggest that Ad21 might cause AFP by anterior horn cell damage or neuropathy of the brachial or lumbosacral plexus. The occurrence of these unusual adenovirus infections during an outbreak of EV71-associated HFMD suggests that an interaction between the 2 viruses may have occurred.

Acute Disease↗
PubMed2003

Origin and evolution of Japanese encephalitis virus in southeast Asia.

Since it emerged in Japan in the 1870s, Japanese encephalitis has spread across Asia and has become the most important cause of epidemic encephalitis worldwide. Four genotypes of Japanese encephalitis virus (JEV) are presently recognized (representatives of genotypes I to III have been fully sequenced), but its origin is not known. We have determined the complete nucleotide and amino acid sequence of a genotype IV Indonesian isolate (JKT6468) which represents the oldest lineage, compared it with other fully sequenced genomes, and examined the geographical distribution of all known isolates. JKT6468 was the least similar, with nucleotide divergence ranging from 17.4 to 19.6% and amino acid divergence ranging from 4.7 to 6.5%. It included an unusual series of amino acids at the carboxy terminus of the core protein unlike that seen in other JEV strains. Three signature amino acids in the envelope protein (including E327 Leu-->Thr/Ser on the exposed lateral surface of the putative receptor binding domain) distinguished genotype IV strains from more recent genotypes. Analysis of all 290 JEV isolates for which sequence data are available showed that the Indonesia-Malaysia region has all genotypes of JEV circulating, whereas only more recent genotypes circulate in other areas (P < 0.0001). These results suggest that JEV originated from its ancestral virus in the Indonesia-Malaysia region and evolved there into the different genotypes which then spread across Asia. Our data, together with recent evidence on the origins of other emerging viruses, including dengue virus and Nipah virus, imply that tropical southeast Asia may be an important zone for emerging pathogens.

Amino Acid Sequence↗
PubMed2003

Molecular epidemiology of human enterovirus 71 strains and recent outbreaks in the Asia-Pacific region: comparative analysis of the VP1 and VP4 genes.

This study provides a comprehensive overview of the molecular epidemiology of human enterovirus 71 (HEV71) in the Asia-Pacific region from 1997 through 2002. Phylogenetic analysis of the VP4 and VP1 genes of recent HEV71 strains indicates that several genogroups of the virus have been circulating in the Asia-Pacific region since 1997. The first of these recent outbreaks, described in Sarawak (Malaysian Borneo) in 1997, was caused by genogroup B3. This outbreak was followed by large outbreaks in Taiwan in 1998, caused by genogroup C2, and in Perth (Western Australia) in 1999, where viruses belonging to genogroups B3 and C2 cocirculated. Singapore, Taiwan, and Sarawak had HEV71 epidemics in 2000, caused predominantly by viruses belonging to genogroup B4; however, large numbers of fatalities were observed only in Taiwan. HEV71 was identified during an epidemic of hand, foot and mouth disease in Korea; that epidemic was found to be due to viruses constituting a new genogroup, C3.

Asia, Southeastern↗
PubMed2002

Antibodies against prM protein distinguish between previous infection with dengue and Japanese encephalitis viruses.

BACKGROUND: In Southeast Asia, dengue viruses often co-circulate with other flaviviruses such as Japanese encephalitis virus, and due to the presence of shared antigenic epitopes it is often difficult to use serological methods to distinguish between previous infections by these flaviviruses. RESULTS: Convalescent sera from 69 individuals who were known to have had dengue or Japanese encephalitis virus infection were tested by western blotting against dengue, Japanese encephalitis and West Nile virus antigens. We determined that individuals who had been infected with dengue viruses had IgG responses against the premembrane protein of dengue viruses but not Japanese encephalitis, whereas individuals who had been infected with Japanese encephalitis had IgG specific for the premembrane protein of Japanese encephalitis virus but not the dengue viruses. None reacted with the premembrane protein of West Nile virus. Using the Pearson Chi Square test, it was determined that the difference between the two groups was highly significant with a p value of <0.001. CONCLUSION: The use of flavivirus premembrane protein in seroepidemiological studies will be useful in determining what flaviviruses have circulated in a community.

Aedes↗
PubMed2000

Dengue haemorrhagic fever: questions of pathogenesis.

The year under review has seen a remarkable proliferation of papers on dengue. Four prospective studies have been carried out across the dengue belt, many groups have been pushing at the question of pathogenesis of dengue haemorrhagic fever, and a breakthrough has been achieved in the development of a mouse model for human dengue haemorrhagic fever.

Journal Article↗