To investigate the hypotensive and angiotensin-converting enzyme (ACE) inhibitory activities of a partially purified fraction (FA-I) of the leaves of Gynura procumbens and to qualitatively analyse the putative compounds present in the fraction.
Exanthem subitum (ES) is a common childhood exanthematous disease. In a recent study of ES due to human herpesvirus 6 (HHV 6), we isolated human herpesvirus 7 (HHV 7) from the peripheral blood mononuclear cells (PBMC) of a seven month-old infant with typical symptoms of ES. The identity of the virus was confirmed by indirect immunofluorescence using HHV 7 specific monoclonal antibody and by amplification of the HHV 7 specific genomic sequences using the polymerase chain reaction (PCR). Paired serum samples from the infant showed serological conversion to the isolated virus. The clinical manifestations of ES in this infant appeared to be milder than the classical ES due to HHV 6.
In vitro generated cloned full length dengue 2 virus untranslated regions (UTRs) were used in RNA gel mobility shift assays to examine cellular factors binding to the virus genomes. Cellular factors in lysates of Vero (monkey) and C6/36 (mosquito) cells bound specifically and non-specifically to the dengue 2 virus 3' UTR. Non-specific interaction with the 5' UTR, resulting in formation of at least 4 band shift complexes was noted with lysate of the C6/36 cells only. Pre-treating the cell lysates with proteinase K affected binding of cellular factors to the dengue 2 virus UTRs, suggesting that the cellular factors were proteins. These findings suggest that cellular proteins could interact with specific sites on the dengue virus genomes.
The limited sequencing approach was used to study the molecular epidemiology of 24 Malaysian dengue 2 viruses which were isolated between 1968 and 1993. The sequences of a 240-nucleotide-long region across the envelope/non-structural 1 protein (E/NS1) gene junction of the isolates were determined and analysed. Alignment and comparison of the nucleotide and deduced amino acid sequences of the isolates revealed that nucleotide changes occurred mostly at the third position of a particular codon and were of the transition (AG, CU) type. Five nucleotide changes resulted in amino acid substitutions. Pairwise comparisons of the nucleotide sequences gave divergence values ranging from 0 to 9.2%. At the amino acid level, the divergence ranged between 0 and 3.8%. Based on the 6% divergence as the cut-off point for genotypic classification, the isolates were grouped into two genotypes, I and II. Comparison of the nucleotide sequences of the Malaysian dengue isolates with those of the dengue viruses of other regions of the world revealed that members of genotypes I and II were closely related to viruses from the Indian Ocean and Western Pacific regions, respectively.
A 17-year-old girl was admitted to hospital with dengue fever. On the ninth day of fever she developed haemoptysis and chest X-ray changes consistent with haemorrhage in her lungs. Thrombocytopaenia and mild coagulopathy were the most likely cause of this unusual haemoptysis in this patient. Investigations excluded other causes for the haemoptysis.
A cytotoxic T lymphocyte (CTL) response to dengue virus-infected target cells is described. Effector cells were generated in an in vitro secondary culture and appeared to be T cells possessing both the Lyt 1.1 and Lyt 2.1 surface antigens. A stronger CTL response was noted with the H-2k haplotype compared to H-2d, and H-2 compatibility was required between CTL and target cells. CTL generated showed some cross-reactivity with target cells infected with Japanese encephalitis virus (JEV), another flavivirus, but not with target cells infected with an alphavirus, Sindbis. The significance and importance of these findings are discussed.
Dengue viruses pose a considerable global public health problem with an estimated 100 million cases of illness every year. This illustrates the need for rapid and reliable diagnostic methods for proper patient management and disease control. Currently, laboratory diagnosis depends on serology or virus isolation, with both methods having certain drawbacks. Alternatively, reverse transcription and polymerase chain reaction (RT-PCR) offers the potential for the rapid, highly sensitive and specific detection of dengue viruses. Since we occasionally encounter the problem of insufficient amounts of patient serum for the direct detection of dengue viruses, a method was developed for the extraction of viral RNA after biological amplification in mosquito larvae. Using this method, 15 of 19 clinical samples tested were correctly identified using RT-PCR.
Eight cases of liver failure and encephalopathy were observed among twenty cases of grade 3 and grade 4 dengue hemorrhagic fever/dengue shock syndrome admitted to the Department of Pediatrics, University Hospital, Kuala Lumpur from January 1990 to December 1991. All patients with deterioriation in mental status showed a marked increase in liver enzymes (aspartate and alanine aminotransaminases) and severe coagulopathy. Six patients needed cerebral protection, including ventilation, intravenous sedation and muscle relaxants. There was one death during the period of study and one case of residual hemiparesis in a boy who had, in addition, intracerebral hemorrhage. All other survivors had complete recovery of liver and neurological function.
The potential of RT-PCR to rapidly diagnose dengue infections from both acute and convalescent phase patients' sera was evaluated. The RNA extraction method involved binding of the viral RNA to silica particles in the presence of high concentration of guanidine thiocyanate. The protocol that was established was sensitive enough to detect 40 plaque forming units per 100 microliter of serum and results could be obtained within one day. Results from this study indicate that clinical samples should be collected in the early acute phase of illness when anti-dengue antibodies were undetectable or of low titres to ensure a more reliable diagnosis.
The results of this study indicate that the important viral agents associated with lower respiratory tract infections in young children are respiratory syncytial virus, rhinovirus, and parainfluenza virus, particularly in those under 2 years of age. This is in close agreement with studies done in temperate climates. Influenza A virus is seasonal and plays an important role in upper respiratory tract infections in older children.
Study site: Inpatients and outpatients, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
Paired sera from 101 Malaysian children aged up to 10 years and suffering from respiratory illnesses were examined serologically for evidence of respiratory viral infections. Of these children, 32.6% showed rising antibody titres for one or more of the test agents. Respiratory syncytial virus appeared to be the main respiratory pathogen involved, followed by Mycoplasma pneumoniae, parainfluenza viruses, adenoviruses, and influenza A virus. These findings are generally similar to those reported by others in temperate and tropical countries.
This is a 10-year retrospective review of mucocutaneous infection by human herpesvirus 1 (HHV1) and human herpesvirus 2 (HHV2) carried out by the virus diagnostic unit of University Malaya Medical Centre (UMMC). A total of 504 specimens from UMMC and a private clinic in the same city (KLSC) were tested; 198 samples from patients with oral lesions and 306 from patients with genital lesions. HHV1 was found to be responsible for 98.4% of oral lesions whereas HHV2 was the cause of 83.6% of all genital lesions. Detailed analysis showed no statistical difference by age group, race or gender among the patients with oral and genital lesions. Two laboratory methods were used in this study. Of the total 504 specimens tested, 18.0% specimens were positive by direct immunofluorescence (IF), 55.0% by virus isolation and 56.5% when both methods were used in combination. Although IF can provide a more rapid diagnosis, it is, however, less sensitive and can be attributed partly to inadequate collection of specimens.
A novel paramyxovirus in the genus Rubulavirus, named Tioman virus (TiV), was isolated in 1999 from a number of pooled urine samples of Island Flying Foxes (Pteropus hypomelanus) during the search for the reservoir host of Nipah virus. TiV is antigenically related to Menangle virus (MenV) that was isolated in Australia in 1997 during disease outbreak in pigs. Sequence analysis of the full length genome indicated that TiV is a novel member of the genus Rubulavirus within the subfamily Paramyxovirinae, family Paramyxoviridae. However, there are several features of TiV which make it unique among known paramyxoviruses and rubulaviruses in particular: (1) TiV, like MenV, uses the nucleotide G as a transcriptional initiation site, rather than the A residue used by all other known paramyxoviruses; (2) TiV uses C as the +1 residue for all intergenic regions, a feature not seen for rubulaviruses but common for all other members within the subfamily Paramyxovirinae; (3) Although the attachment protein of TiV has structural features that are conserved in other rubulaviruses, it manifests no overall sequence homology with members of the genus, lacks the sialic acid-binding motif N-R-K-S-C-S and has only two out of the six highly conserved residues known to be important for the catalytic activity of neuraminidase.
Enterovirus 5'UTR sequences were detected by RT-PCR in 22 out of 47 suspected hand, foot and mouth disease (HFMD) patients during an outbreak of the disease with incidences of fatal brainstem encephalomyelitis in Malaysia in 1997. Genetic and phylogenetic analyses of the isolates 5'UTR sequences suggest the presence of predominantly enteroviruses with high sequence similarities to Echovirus 1 and Coxsackievirus A9 in the Malaysian peninsula. No fatal cases, however, were associated with these isolates. The remaining isolates, including all (4/4) isolates of the fatal cases from the Malaysian peninsula and Sarawak shared very high sequence identity with enterovirus 71MS (EV71). These findings suggest that several enteroviruses were circulating in Malaysia during the outbreak period, with only EV71 causing fatal infections.
A provisional clinical diagnosis of exanthem subitum was made in six febrile infants seen in the Paediatric Unit of Assunta Hospital, Petaling Jaya, Malaysia with uvulo-palatoglossal junctional ulcers prior to the eruption of maculopapular rash. On follow-up, all six infants developed maculopapular rash with the subsidence of fever at the end of the fourth febrile day. Human herpesvirus 6 was isolated from the peripheral blood mononuclear cells during the acute phase of the illness and HHV 6 specific genome was also detected in these cells by nested polymerase chain reaction. All the six infants showed seroconversion for both specific IgG and IgM to the isolated virus. This study suggests that the presence of uvulo-palatoglossal junctional ulcers could be a useful early clinical sign of exanthem subitum due to human herpesvirus 6.
From October 1996 to March 1997, 31 children with febrile convulsions were admitted to the University Hospital, Kuala Lumpur. Human Herpesvirus 6 (HHV 6) was virologically and/or serologically confirmed to be the cause of the febrile episode in 5 of these children (16.1%). Age, sex and other associated clinical features (diarrhoea, cough, running nose and type of seizure) were not useful in differentiating cases of febrile convulsion due to HHV 6 from those of other aetiology. However, uvulo-palatoglossal junctional ulcers were noted in children in whom the cause of the seizure could be attributed to HHV 6 but not in the remaining cases in the study group. HHV 6 DNA was detected in peripheral blood mononuclear cells from all patients with febrile convulsions attributed to HHV6, and in patients shown serologically to have already been exposed to the virus by nested polymerase chain reaction amplification. Only genotype HHV 6B was detected from patients with seizure due to HHV 6 but both genotype 6A and 6B were detected in the remaining cases studied.