[show abstract][hide abstract] ABSTRACT: PURPOSE: We looked for herpes simplex virus types 1 and 2 (HSV-1 and HSV-2, respectively), varicella zoster virus (VZV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) DNA in Malawian adults with clinically suspected meningitis. METHODS: We collected cerebrospinal fluid (CSF) from consecutive adults admitted with clinically suspected meningitis to Queen Elizabeth Central Hospital (QECH), Blantyre, Malawi, for a period of 3 months. Those with proven bacterial or fungal meningitis were excluded. Real-time polymerase chain reaction (PCR) was performed on the CSF for HSV-1 and HSV-2, VZV, EBV and CMV DNA. RESULTS: A total of 183 patients presented with clinically suspected meningitis. Of these, 59 (32 %) had proven meningitis (bacterial, tuberculous or cryptococcal), 39 (21 %) had normal CSF and 14 (8 %) had aseptic meningitis. For the latter group, a herpes virus was detected in 9 (64 %): 7 (50 %) had EBV and 2 (14 %) had CMV, all were human immunodeficiency virus (HIV)-positive. HSV-2 and VZV were not detected. Amongst those with a normal CSF, 8 (21 %) had a detectable herpes virus, of which 7 (88 %) were HIV-positive. CONCLUSIONS: The spectrum of causes of herpes viral meningitis in this African population is different to that in Western industrialised settings, with EBV being frequently detected in the CSF. The significance of this needs further investigation.
[show abstract][hide abstract] ABSTRACT: Mortality from adult bacterial meningitis exceeds 50% in sub-Saharan Africa. We postulated that-particularly in individuals infected with human immunodeficiency virus (HIV)-herpes simplex virus, varicella zoster virus, Epstein-Barr virus (EBV), and cytomegalovirus (CMV) in the cerebrospinal fluid (CSF) contribute to poor outcome. CSF from 149 Malawian adults with bacterial meningitis and 39 controls were analyzed using polymerase chain reaction. EBV was detected in 79 of 149 bacterial meningitis patients. Mortality (54%) was associated with higher CSF EBV load when adjusted for HIV (P = .01). CMV was detected in 11 of 115 HIV-infected patients, 8 of whom died. The mechanisms by which EBV and CMV contribute to poor outcome require further investigation.
The Journal of Infectious Diseases 11/2011; 205(1):106-10. · 5.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dengue viruses (DENV) cause countless human deaths each year, whilst West Nile virus (WNV) has re-emerged as an important human pathogen. There are currently no WNV or DENV vaccines licensed for human use, yet vaccines exist against other flaviviruses. To investigate flavivirus cross-reactivity, sera from a human cohort with a history of vaccination against tick-borne encephalitis virus (TBEV), Japanese encephalitis virus (JEV) and yellow fever virus (YFV) were tested for antibodies by plaque reduction neutralization test. Neutralization of louping ill virus (LIV) occurred, but no significant neutralization of Murray Valley encephalitis virus was observed. Sera from some individuals vaccinated against TBEV and JEV neutralized WNV, which was enhanced by YFV vaccination in some recipients. Similarly, some individuals neutralized DENV-2, but this was not significantly influenced by YFV vaccination. Antigenic cartography techniques were used to generate a geometric illustration of the neutralization titres of selected sera against WNV, TBEV, JEV, LIV, YFV and DENV-2. This demonstrated the individual variation in antibody responses. Most sera had detectable titres against LIV and some had titres against WNV and DENV-2. Generally, LIV titres were similar to titres against TBEV, confirming the close antigenic relationship between TBEV and LIV. JEV was also antigenically closer to TBEV than WNV, using these sera. The use of sera from individuals vaccinated against multiple pathogens is unique relative to previous applications of antigenic cartography techniques. It is evident from these data that notable differences exist between amino acid sequence identity and mapped antigenic relationships within the family Flaviviridae.
Journal of General Virology 09/2011; 92(Pt 12):2821-9. · 3.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: Japanese encephalitis virus (JEV) is the most important cause of epidemic encephalitis worldwide but its origin is unknown. Epidemics of encephalitis suggestive of Japanese encephalitis (JE) were described in Japan from the 1870s onwards. Four genotypes of JEV have been characterised and representatives of each genotype have been fully sequenced. Based on limited information, a single isolate from Malaysia is thought to represent a putative fifth genotype. We have determined the complete nucleotide and amino acid sequence of Muar strain and compared it with other fully sequenced JEV genomes. Muar was the least similar, with nucleotide divergence ranging from 20.2 to 21.2% and amino acid divergence ranging from 8.5 to 9.9%. Phylogenetic analysis of Muar strain revealed that it does represent a distinct fifth genotype of JEV. We elucidated Muar signature amino acids in the envelope (E) protein, including E327 Glu on the exposed lateral surface of the putative receptor binding domain which distinguishes Muar strain from the other four genotypes. Evolutionary analysis of full-length JEV genomes revealed that the mean evolutionary rate is 4.35 × 10(-4) (3.4906 × 10(-4) to 5.303 × 10(-4)) nucleotides substitutions per site per year and suggests JEV originated from its ancestral virus in the mid 1500s in the Indonesia-Malaysia region and evolved there into different genotypes, which then spread across Asia. No strong evidence for positive selection was found between JEV strains of the five genotypes and the E gene has generally been subjected to strong purifying selection.
Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 02/2011; 11(5):855-62. · 3.22 Impact Factor
[show abstract][hide abstract] ABSTRACT: West Nile virus (WNV) was first detected in Texas in 2002. During 2003, several isolates exhibiting significant attenuation of mouse neuroinvasiveness, and in some cases a small plaque and temperature sensitive phenotype when compared to other North American WNV isolates, were obtained from birds and mosquitoes in South-East Texas. To determine the attenuation markers of WNV, we have sequenced the genomes of three attenuated isolates and four temporally related virulent isolates and compared the amino acid substitutions in a total of 101 isolates, including three previously published genomes of attenuated strains, to identify mutations that are potentially involved in attenuation. Surprisingly, the attenuated strains fall into three separate "groups", suggesting that the attenuated phenotype evolved on three separate occasions in 2003. None of the groups share the same nucleotide changes or amino acid substitutions, and there are few mutations that can be clearly defined alone as being associated with attenuation.
[show abstract][hide abstract] ABSTRACT: Phylogenetic analysis of West Nile virus in North America has identified replacement of the originally introduced clade, Eastern United States (NY99), by the North American clade. In addition, the transient emergence of other clades and genetic variants has also been observed. In this study, we investigated the potential role of the mosquito in the selection of these clades and genetic variants. We determined the relative susceptibility of Culex quinquefasciatus to infection with isolates from the Eastern U.S. clade, the North American clade, and the Southeast coastal Texas clade. Although significant differences were observed in 50% oral infectious dose values between the Eastern U.S. and two attenuated North American genetic variants compared with the North American and Southeast coastal Texas clade viruses, these differences did not correlate with persistence of the genotype in nature. These results indicate that selection of these viral genotypes was independent of viral oral infectivity in the mosquito.
The American journal of tropical medicine and hygiene 01/2009; 79(6):951-4. · 2.53 Impact Factor
[show abstract][hide abstract] ABSTRACT: We previously reported mutations in North American West Nile viruses (WNVs) with a small-plaque (sp), temperature-sensitive (ts), and/or mouse-attenuated (att) phenotype. Using an infectious clone, site-directed mutations and 3' untranslated region (3'UTR) exchanges were introduced into the WNV NY99 genome. Characterization of mutants demonstrated that a combination of mutations involving the NS4B protein (E249G) together with either a mutation in the NS5 protein (A804V) or three mutations in the 3'UTR (A10596G, C10774U, A10799G) produced sp, ts, and/or att variants. These results suggested that the discovery of North American WNV-phenotypic variants is rare because of the apparent requirement of concurrent polygenic mutations.
Journal of Virology 07/2007; 81(11):6111-6. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background
Varicella zoster virus (VZV) is a common cause of viral encephalitis with wide spectrum of morbidity and mortality. The pathophysiology remains poorly understood and few prognostic markers are available. A few studies have attempted to use the viral load of the cerebrospinal fluid (CSF), to investigate the pathophysiology and prognosis, with contradictory results. However, these studies have not assessed the viral load in the context of time.Objectives
To determine the CSF viral load in VZV encephalitis in relation to time and outcome.Study DesignThe Liverpool Specialist Virology laboratory database was screened to identify patients with CSF positive for VZV over 5 years. Viral load was determined by qPCR. A poor outcome was defined as moderate disability to death (Glasgow outcome score 2–5).Results608 patients were screened, 36 had VZV PCR performed, 12 were positive and had clinical features consistent with encephalitis. There was a strong negative correlation between the time from symptom onset to LP and the viral load (τ b=−0.59, p=0.036). There was no significant difference in viral load between those with good and poor outcome.Conclusions
In this study of VZV encephalitis, CSF viral load appears to more closely relate to time of LP from symptom onset than to outcome. Timing of LP should be taken into account in future studies of viral encephalitis which aim to relate viral load to outcome in viral encephalitis.