Genotype of Varicella-zoster virus isolated in Jiangsu, China.

OBJECTIVE: To analyze the genotypes of VZV in Jiangsu province to identify vaccine strains and wild strains, providing a molecular biological background for the effective prevention and control of varicella. METHOD: Stratified sampling was used to collect herpes fluid or throat swab from patients diagnosed with varicella. ORF22 was carried out, and the restriction enzyme site of ORF38, ORF54 and ORF62 were detected. RESULTS: All 207 virus strains were Clade 2 type by sequencing the PCR products of ORF22. The sequencing results showed that five SNP sites changed compared to the Dumas reference strain(Clade 1). From A to G at 37,902, from T to c at 38,055, from A to C at 38,081, and from G to A at 38,177, from G to A at 39,394. The prevalent VZV genotypes in Jiangsu is consistent with the P-Oka. The restriction enzyme site analysis of PCR amplification products from ORF38 (PstI), ORF54 (BglI), ORF62 (SmaI) showed that all 207 virus strains were wild-type. There were two different types of the wild strains, and 183 strains (88.4%) were PstI (+), BglI (+), SmaI (-). The wild strains between different regions showed no significant differences (χ2 = 0.05, P = 0.982). CONCLUSIONS: The prevalent VZV genotypes are Clade 2 and the prevalent virus strains are wild strains in Jiangsu Province, the primary wild strain observed is mainly PstI (+), BglI (+), SmaI (-).

Classic paper: Are the chickenpox virus and the zoster virus identical?: HELMUT RUSKA.

As early as 1943, the German physician Helmut Ruska visualized the virus of varicella and zoster (at that time, he was not completely certain whether the virus was the same) by the newly developed electron microscope; he is regarded as the discoverer of this virus. Here, we present a translation of his classical paper into the English language. In our introduction and commentary to his paper, we discuss the significance of Helmut Ruska's work for the development of virology, his distinction between the varicella, zoster, and herpes virus group on one hand and poxviruses on the other, as well as the development of imaging techniques which have refined or substituted for electron microscopy of viruses and virus-infected cells.

High Viral Diversity and Mixed Infections in Cerebral Spinal Fluid From Cases of Varicella Zoster Virus Encephalitis.

Background: Varicella zoster virus (VZV) may cause encephalitis, both with and without rash. Here we investigate whether viruses recovered from the central nervous system (CNS; encephalitis or meningitis) differ genetically from those recovered from non-CNS samples. Methods: Enrichment-based deep sequencing of 45 VZV genomes from cerebral spinal fluid (CSF), plasma, bronchoalveolar lavage (BAL), and vesicles was carried out with samples collected from 34 patients with and without VZV infection of the CNS. Results: Viral sequences from multiple sites in the same patient were identical at the consensus level. Virus from vesicle fluid and CSF in cases of meningitis showed low-level diversity. By contrast, plasma, BAL, and encephalitis had higher numbers of variant alleles. Two CSF-encephalitis samples had high genetic diversity, with variant frequency patterns typical of mixed infections with different clades. Conclusions: Low viral genetic diversity in vesicle fluid is compatible with previous observations that VZV skin lesions arise from single or low numbers of virions. A similar result was observed in VZV from cases of VZV meningitis, a generally self-limiting infection. CSF from cases of encephalitis had higher diversity with evidence for mixed clade infections in 2 cases. We hypothesize that reactivation from multiple neurons may contribute to the pathogenesis of VZV encephalitis.

Molecular Genetic Insights Into Varicella Zoster Virus (VZV), the vOka Vaccine Strain, and the Pathogenesis of Latency and Reactivation.

Genetic tools for molecular typing of varicella zoster virus (VZV) have been used to understand the spread of virus, to differentiate wild-type and vaccine strains, and to understand the natural history of VZV infection in its cognate host. Molecular genetics has identified 7 clades of VZV (1-6 and 9), with 2 more mooted. Differences between the vOka vaccine strain and wild-type VZVs have been used to distinguish the cause of postimmunization events and to provide insight into the natural history of VZV infections. Importantly molecular genetics has shown that reinfection with establishment of latency by the reinfecting strain is common, that dual infections with different viruses can occur, and that reactivation of the superinfecting genotype can both occur. Whole-genome sequencing of the vOka vaccine has been used to show that vesicles form from a single virion, that latency is established within a few days of inoculation, and that all vaccine strains are capable of establishing latency and reactivating. Novel molecular tools have characterized the transcripts expressed during latent infection in vitro.

Revisiting the genotyping scheme for varicella-zoster viruses based on whole-genome comparisons.

We report whole-genome sequences (WGSs) for four varicella-zoster virus (VZV) samples from a shingles study conducted by Kaiser Permanente of Southern California. Comparative genomics and phylogenetic analysis of all published VZV WGSs revealed that strain KY037798 is in clade IX, which shall henceforth be designated clade 9. Previously published single nucleotide polymorphisms (SNP)-based genotyping schemes fail to discriminate between clades 6 and VIII and employ positions that are not clade-specific. We provide an updated list of clade-specific positions that supersedes the list determined at the 2008 VZV nomenclature meeting. Finally, we propose a new targeted genotyping scheme that will discriminate the circulating VZV clades with at least a twofold redundancy. Genotyping strategies using a limited set of targeted SNPs will continue to provide an efficient 'first pass' method for VZV strain surveillance as vaccination programmes for varicella and zoster influence the dynamics of VZV transmission.

Genotype analysis of ORF 62 identifies varicella-zoster virus infections caused by a vaccine strain in children.

This study was performed to differentiate vaccine-type strains from wild-type strains and determine the genotype of varicella-zoster virus (VZV) in 51 Korean children. A sequencing analysis of ORF 62 identified two cases of herpes zoster caused by the vaccine-type virus, without a previous history of varicella, 22 months and 5 months after VZV vaccination. The wild-type strain was identified in the remaining children. A genotype analysis of ORF 22 amino acids revealed genotype J in all children except one. Genotype E was identified in an infant with varicella imported from Egypt.

Differentiation between wild-type and vaccines strains of varicella zoster virus (VZV) based on four single nucleotide polymorphisms.

Varicella-zoster virus (VZV) infection (chickenpox) results in latency and subsequent reactivation manifests as shingles. Effective attenuated vaccines (vOka) are available for prevention of both illnesses. In this study, an amplicon-based sequencing method capable of differentiating between VZV wild-type (wt) strains and vOka vaccine is described. A total of 44 vesicular fluid specimens collected from 43 patients (16 from China and 27 from the UK) with either chickenpox or shingles were investigated, of which 10 had received previous vaccination. Four sets of polymerase chain reactions were set up simultaneously with primers amplifying regions encompassing four single nucleotide polymorphisms (SNPs), '69349-106262-107252-108111'. Nucleotide sequences were generated by Sanger sequencing. All samples except one had a wt SNP profile of 'A-T-T-T'. The sample collected from a patient who received vaccine 7-10 days ago, along with VZV vaccine preparations, Zostavax and Baike-varicella gave a SNP profile 'G-C-C-C'. The results show that this method can distinguish vaccine-derived virus from wt viruses from main four clades, (clades 1-4) and should be of utility worldwide.

Evolution of cocirculating varicella-zoster virus genotypes during a chickenpox outbreak in Guinea-Bissau.

UNLABELLED: Varicella-zoster virus (VZV), a double-stranded DNA alphaherpesvirus, is associated with seasonal outbreaks of varicella in nonimmunized populations. Little is known about whether these outbreaks are associated with a single or multiple viral genotypes and whether new mutations rapidly accumulate during transmission. Here, we take advantage of a well-characterized population cohort in Guinea-Bissau and produce a unique set of 23 full-length genome sequences, collected over 7 months from eight households. Comparative sequence analysis reveals that four distinct genotypes cocirculated among the population, three of which were present during the first week of the outbreak, although no patients were coinfected, which indicates that exposure to infectious virus from multiple sources is common during VZV outbreaks. Transmission of VZV was associated with length polymorphisms in the R1 repeat region and the origin of DNA replication. In two cases, these were associated with the formation of distinct lineages and point to the possible coevolution of these loci, despite the lack of any known functional link in VZV or related herpesviruses. We show that these and all other sequenced clade 5 viruses possess a distinct R1 repeat motif that increases the acidity of an ORF11p protein domain and postulate that this has either arisen or been lost following divergence of the major clades. Thus, sequencing of whole VZV genomes collected during an outbreak has provided novel insights into VZV biology, transmission patterns, and (recent) natural history. IMPORTANCE: VZV is a highly infectious virus and the causative agent of chickenpox and shingles, the latter being particularly associated with the risk of painful complications. Seasonal outbreaks of chickenpox are very common among young children, yet little is known about the dynamics of the virus during person-to-person to transmission or whether multiple distinct viruses seed and/or cocirculate during an outbreak. In this study, we have sequenced chickenpox viruses from an outbreak in Guinea-Bissau that are supported by detailed epidemiological data. Our data show that multiple different virus strains seeded and were maintained throughout the 6-month outbreak period and that viruses transmitted between individuals accumulated new mutations in specific genomic regions. Of particular interest is the potential coevolution of two distinct parts of the genomes and our calculations of the rate of viral mutation, both of which increase our understanding of how VZV evolves over short periods of time in human populations.

Herpes zoster caused by vaccine-strain varicella zoster virus in an immunocompetent recipient of zoster vaccine.

We report the first laboratory-documented case of herpes zoster caused by the attenuated varicella zoster virus (VZV) contained in Zostavax in a 68-year-old immunocompetent adult with strong evidence of prior wild-type VZV infection. The complete genome sequence of the isolate revealed that the strain carried 15 of 42 (36%) recognized varicella vaccine-associated single-nucleotide polymorphisms, including all 5 of the fixed vaccine markers present in nearly all of the strains in the vaccine. The case of herpes zoster was relatively mild and resolved without complications.

[Infections caused by human alpha herpes viruses]. / Infekce vyvoláné lidskými alfa herpetickými viry.

Varicella-zoster virus (VZV), herpes simplex virus one (HSV-1) and herpes simplex virus two (HSV-2) represent three out of the eight known human herpesviruses and belong to the subfamily of α-herpesviruses. These viruses are present worldwide and humans are their sole host and reservoir. After the primary infection, these viruses persist in the body throughout life. The period of latency may be interrupted by reactivation of infection due to various factors. Each virus can induce a wide spectrum of diseases. The primary infection is typical for children and otherwise healthy individuals are often asymptomatic. It is mainly immunocompromised patients who are at risk of developing severe disease or complications when infected by these viruses. However, even in otherwise healthy individuals an infection by a-herpesviruses can run a severe course and lead to death.

Sequencing of 21 varicella-zoster virus genomes reveals two novel genotypes and evidence of recombination.

Genotyping of 21 varicella-zoster virus (VZV) strains using a scattered single nucleotide polymorphism (SNP) method revealed ambiguous SNPs and two nontypeable isolates. For a further genetic characterization, the genomes of all strains were sequenced using the 454 technology. Almost-complete genome sequences were assembled, and most remaining gaps were closed with Sanger sequencing. Phylogenetic analysis of 42 genomes revealed five established and two novel VZV genotypes, provisionally termed VIII and IX. Genotypes VIII and IX are distinct from the previously reported provisional genotypes VI and VII as judged from the SNP pattern. The alignments showed evidence of ancient recombination events in the phylogeny of clade 4 and recent recombinations within single strains: 3/2005 (clade 1), 11 and 405/2007 (clade 3), 8 and DR (clade 4), CA123 and 413/2000 (clade 5), and strains of the novel genotypes VIII and IX. Bayesian tree inference of the thymidine kinase and the polymerase genes of the VZV clades and other varicelloviruses revealed that VZV radiation began some 110,000 years ago, which correlates with the out-of-Africa dispersal of modern humans. The split of ancestral clades 2/4 and 1/3/5/VIII/IX shows the greatest node height.

Pangaea and the Out-of-Africa Model of Varicella-Zoster Virus Evolution and Phylogeography.

The goal of this minireview is to provide an overview of varicella-zoster virus (VZV) phylogenetics and phylogeography when placed in the broad context of geologic time. Planet Earth was formed over 4 billion years ago, and the supercontinent Pangaea coalesced around 400 million years ago (mya). Based on detailed tree-building models, the base of the phylogenetic tree of the Herpesviridae family has been estimated at 400 mya. Subsequently, Pangaea split into Laurasia and Gondwanaland; in turn, Africa rifted from Gondwanaland. Based on available data, the hypothesis of this minireview is that the ancestral alphaherpesvirus VZV coevolved in simians, apes, and hominins in Africa. When anatomically modern humans first crossed over the Red Sea 60,000 years ago, VZV was carried along in their dorsal root ganglia. Currently, there are five VZV clades, distinguishable by single nucleotide polymorphisms. These clades likely represent continued VZV coevolution, as humans with latent VZV infection left Arabia and dispersed into Asia (clades 2 and 5) and Europe (clades 1, 3, and 4). The prototype VZV sequence contains nearly 125,000 bp, divided into 70 open reading frames. Generally, isolates within a clade display >99.9% identity to one another, while members of one clade compared to a second clade show 99.8% identity to one another. Recently, four different VZV genotypes that do not segregate into the previously defined five clades have been identified, a result indicating a wider than anticipated diversity among newly collected VZV strains around the world.

Molecular characterization of varicella-zoster virus clinical isolates from 2006 to 2008 in a tertiary care hospital, Dublin, Ireland, using different genotyping methods.

Varicella-zoster virus (VZV), a herpesvirus, is a ubiquitous organism that causes considerable morbidity worldwide and can cause severe complications on reactivation. Phylogenetic analysis was performed on 19 clinical VZV isolates (16 zoster and 3 varicella) found in Ireland, between December 2006 and November 2008, in order to determine whether previously reported viral heterogeneity was still present and whether viral recombination was evident. Open reading-frames (ORFs) from genes 1, 21, 50, and 54, were sequenced. Clades 1, 2, 3, and 5 were identified. Four putative recombinant isolates were detected (three clade 3/1 and one clade 5/3/1). Further sequencing and examination of ORF 22 and 21/50, did not elucidate the putative recombinant genotypes further. These two previously published genotyping schemes were examined in light of the new consensus genotyping scheme proposed in 2010. Remarkable VZV heterogeneity remains prevalent in Ireland. This is the first evidence of putative VZV recombination found in Ireland.

Herpes simplex encephalitis and management of acyclovir in encephalitis patients in France.

This study reports on the clinical profiles of herpes simplex encephalitis (HSE) case-patients and the management of acyclovir prescriptions. We designed a study on the causes of encephalitis in France in 2007. Case-patients fulfilling the inclusion criteria were enrolled in all the hospitals that volunteered to participate. Fifty-five of 253 enrolled case-patients were diagnosed with HSE. Three (5%) HSE patients died and 48 (89%) were discharged with persistent neurological symptoms. All HSE patients were prescribed acyclovir, 10 of whom had a 2-week course; 42 a 3-week course; two received incomplete courses; and one received two courses of 21 days each due to relapse. The acyclovir dosage was reported for 45 adult HSE patients, 25 (53%) of whom received 10 mg/kg t.i.d. and 22 (47%) received 15 mg/kg t.i.d. The mortality rate was low despite 49% of patients being admitted to intensive-care units. A high dose of acyclovir was not associated with a better outcome in HSE patients. Most patients had persisting symptoms on discharge suggesting neuropsychological rehabilitation is an important issue for survivors.

Genotype of varicella-zoster virus isolates in South Korea.

Information about the genotype of varicella-zoster virus (VZV) is useful to monitor outbreaks of vaccine strains. However, in South Korea, where varicella vaccine was introduced in 1988, there are limited data about the genotype of VZV. VZV was isolated from vesicular lesions of patients with herpes zoster or varicella in South Korea between January 2007 and June 2009. DNAs were purified from single-passage isolates. The genotype was determined by sequence analysis of open reading frame (ORF) 22. The PstI restriction enzyme site in ORF 38 and the BglI restriction enzyme site in ORF 54 were evaluated by restriction enzyme analysis. Forty-four patients with herpes zoster and nine patients with varicella were enrolled. The median age of patients with herpes zoster was 59.5 (range, 10 to 77) years, and the median age of patients with varicella was 8 (range, 6 to 9) years. In sequence analysis of ORF 22, all isolates were genotype J, irrespective of the age group. In restriction enzyme analysis, 51 of 54 (94.3%) isolates contained a PstI site in ORF 38, and all isolates contained a BglI site in ORF 54. Our data suggest that genotype J has been circulating since the 1940s in South Korea.

Monitoring prevalence of varicella-zoster virus clades in Germany.

The global surveillance of varicella-zoster virus (VZV) clades is an important tool for investigation into viral evolution, host-virus interactions, role of immigration and travel for importation of viral strains as well as possible recombination events between wild- and vaccine-type VZV strains. In this prospective study, comprehensive data on the current distribution of VZV clades in Germany were collected. VZV strains from 213 patients with varicella and 109 with zoster were genotyped using the scattered single-nucleotide polymorphism method on the basis of sequencing open reading frames 1, 21, 22, 37, 50, 54 and 60. In varicella, clade 3 was detected in 45.5%, clade 1 in 30.0%, clade 5 in 21.1% and clade 2 in 0.9% of the cases. The analysis of zoster strains revealed clade 3 in 50.5%, clade 1 in 46.8%, clade 2 and clade 4 in 0.9% of the cases each. Five strains from varicella and one strain from zoster could not be attributed to any of the major and provisional VZV clades. Statistical analysis verified significantly lower frequency of clade 1 and significantly higher frequency of clade 5 in patients with varicella compared to zoster. In addition, varicella patients with clade 5 strains were significantly younger than the patients with clade 3. In conclusion, almost one half of VZV infections in Germany were caused currently by VZV clade 3. In primary VZV infection, nearly 20% of clade 1 has been replaced by clade 5 that might spread more effectively in the population than the European VZV clades.

A proposal for a common nomenclature for viral clades that form the species varicella-zoster virus: summary of VZV Nomenclature Meeting 2008, Barts and the London School of Medicine and Dentistry, 24-25 July 2008.

Varicella-zoster virus (VZV), the cause of chickenpox and zoster, was the first human herpesvirus to be sequenced fully and the first for which vaccines have been licensed and widely used. Three groups have published genotyping schemes based on single nucleotide polymorphisms (SNPs) and, between them, have identified five distinct phylogenetic clades, with an additional two putative clades. Sequencing of over 23 whole VZV genomes from around the world further refined the phylogenetic distinctions between SNP genotypes. Widespread surveillance in countries in which the varicella vaccine is now in use and the difficulties posed by three unique genotyping approaches prompted an international meeting, at which a common nomenclature based on phylogenetic clades was agreed upon. In this paper, we review the original genotyping schemes and discuss the basis for a novel common nomenclature for VZV strains. We propose a minimum set of SNPs that we recommend should be used to genotype these viruses. Finally, we suggest criteria by which novel clades can be recognized.

Simultaneous cocirculation of both European varicella-zoster virus genotypes (E1 and E2) in Mexico city.

Full-length genome analysis of varicella-zoster virus (VZV) has shown that viral strains can be classified into seven different genotypes: European (E), Mosaic (M), and Japanese (J), and the E and M genotypes can be further subclassified into E1, E2, and M1 through 4, respectively. The distribution of the main VZV genotypes in Mexico was described earlier, demonstrating the predominance of E genotype, although other genotypes (M1 and M4) were also identified. However, no information regarding the circulation of either E genotype in the country is available. In the present study, we confirm the presence of both E1 and E2 genotypes in the country and explore the possibility of coinfection as the triggering factor for increased virulence among severe cases. A total of 61 different European VZV isolates collected in the Mexico City metropolitan area from 2005 to 2006 were typed by using a PCR method based on genotype-specific primer amplification. Fifty isolates belonged to the E1 genotype, and the eleven remaining samples were classified as E2 genotypes. No coinfection with both E genotypes was identified among these specimens. We provide here new information on the distribution of VZV genotypes circulating in Mexico City.

Determination of the geographical origin of unidentified cadavers based on geographical differences in genotype of varicella-zoster virus.

A new method was developed for determining the geographical origin of unidentified cadavers by examining the genome of varicella-zoster virus (VZV), which resides latently throughout life in most individuals and the genotypes which show distinct geographical distribution. VZV DNA samples extracted from the trigeminal ganglia of 62 cadavers (59 from Japan, and 1 each from the United Kingdom, Mongolia, and Pakistan) submitted for medico-legal autopsy were examined. Sequencing was performed on a 358-bp region in the open reading frame (ORF) 22 containing four single nucleotide polymorphisms (SNPs) and a 419-bp region in ORF 62 containing 2 SNPs in the VZV genome. Using these SNP markers, the VZV genome was classified into the nine genotypes described previously. Phylogenetic tree analysis was also undertaken for the sequenced regions and for the 22 existing VZV strains described previously. In addition, 21 samples were subcloned for detection of co-infection. The VZV genome was classified successfully into nine genotypes using four SNPs in ORF 22 and two SNPs in ORF 62 as markers. Among Japanese cadavers, 57 carried genotype J, 1 carried genotype M1, and 1 carried genotype M2. The British and the Mongolian cadavers carried genotype E1 and the Pakistani cadaver carried M1. Phylogenetic tree analysis showed that VZV strains can be classified into different genotypes with high bootstrap values. None of the subcloned samples showed evidence of co-infection. These results suggest that valuable additional information for determining the geographical origin of unidentified cadavers can be provided by examining the VZV genome.