Varicella-zoster Virus Genotypes Research Articles

M2 Genotype of Varicella zoster virus associated with Severe Herpes zoster in Pakistan

M2 Genotype of Varicella zoster virus associated with Severe Herpes zoster in Pakistan

A hidden dilemma; post COVID-19 first detection of Varicella zoster M4 genotype from Pakistan

ObjectivesDuring the COVID-19 pandemic, the risk of childhood infectious diseases was increased. Post-COVID-19 escalation of chickenpox cases, becoming an emerging public health concern. Thus, the study was designed to compare chickenpox prevalence and Varicella zoster virus (VZV) genotypes circulating before, during, and post-COVID-19 in Pakistan. MethodsA total of 267 lesion specimens collected from tertiary care hospitals, and chickenpox outbreaks from Pakistan were analysed by a two-amplicon approach with phylogenetic analysis. ResultsAmong suspected cases, overall 178/267 were VZV positive. Majority (84.2 %; 150/178) cases were of post-COVID-19 pandemic time. Small outbreaks occurred soon after COVID-19 in Rawalpindi and Islamabad (Pakistan), 40 positive cases out of 178 cases were outbreak cases. There was first time detection of the M4 genotype, which was significantly associated with disease severity (p = 0.0006) and post-COVID-19 chickenpox outbreaks in 2021 (77.9 %; 46/59; p < 0.00001). However, in pre-COVID-19 only M2 genotype was detected. The M2 prevalence varied from 2019 (100 %; 19/19) to 2022 (3.2 %; 3/91). However, the most prevalent strain of 2022 belonged to the M1 genotype (64.8 %; 59/91). ConclusionA significant rise in chickenpox cases detected soon after COVID-19 in Pakistan, and oscillation of different VZV genotypes with first time detection of M4 genotype is an alarming situation. This demands further detailed genotypic studies on transmission dynamics of a rare M4 with other genotypes to protect the local population and restrict spread in other regions.

Studying the genetic diversity of the varicella-zoster virus in selected regions of the Russian Federation using high-throughput sequencing

Introduction. Varicella-zoster virus (VZV), the causative agent of the disease of the same name and herpes zoster, is phylogenetically divided into 8 clades, the distribution of which is characterized by geographic reference to certain regions of the world. For most countries, VZV clades circulating in their territories have been identified, however, such information is almost unavailable for Russia.&#x0D; The purpose of the study is to develop an effective method for VZV typing using high-throughput sequencing technologies to identify the prevalence of various VZV clades in Moscow, Moscow Region, and Stavropol Territory.&#x0D; Materials and methods. To genotype VZV, it is enough to refer to 7 nucleotide positions. Their unique combinations can be used to assign the virus to one of the clades. Short sections of nucleotide sequences of open reading frames were obtained using a developed set of primers.&#x0D; Results. A VZV genotyping technique has been developed and optimized. Using this technique, primary data on the distribution of VZV clades in the studied regions have been obtained. Thus, it has been established that in Moscow and a number of other regions, the 1st, 3rd, and 5th clades of VZV are predominantly distributed.&#x0D; Conclusion. The developed technique, including a primer panel and a genotyping algorithm, allows VZV typing in a short time while reducing specimen preparation costs and simultaneously increasing the number of specimens in one sequencing cycle. The results obtained using this assay allow us to assume that in Moscow, Moscow Region, Stavropol Territory, VZV, clades 1, 3, and 5 are the most represented ones. To confirm this hypothesis, it is necessary to include a larger number of clinical specimens in subsequent studies, including from other regions of the country.

Clinical features of varicella-zoster virus caused neurological diseases detected by metagenomic next-generation sequencing.

Clinical presentation of central nervous system (CNS) infections caused by varicella-zoster virus (VZV) is highly sophisticated, making identification challenging. We retrospectively reported 18 cases of VZV neurologic disease confirmed by metagenomic next-generation sequencing (mNGS). The detection rate of mNGS was higher than that of PCR assay (100 vs 66.7%, p < 0.05) and serum IgM antibody (100 vs 68.8%, p < 0.05) measurement. Of the 18 cases, five patients were diagnosed with acute meningitis, three with acute meningitis combined with facial neuritis, three with acute meningitis combined with polycranial neuritis, and the remaining seven with various clinical diagnoses. Typical clinical symptoms included headache (15), fever (9), and rash (11). Cranial or spinal MRI showed abnormalities in 12 patients, and 17 patients had obvious neurological symptoms. The predominant genotype of VZV in this study was genotype J (100%, 10/10). All patients were treated with acyclovir/penciclovir and dexamethasone, 16 recovered and 2 died. Our study highlights the good performance of mNGS in diagnosing CNS infection caused by VZV. It could provide additional diagnostic evidence in patients with diverse clinical spectrum and variable manifestations.

Genetic characterization of varicella-zoster virus in people aged 20 years and under in Yichang City of Hubei Province, 2019-2020

Objective: To analyze the genetic characteristics of varicella-zoster virus (VZV) in people aged 20 years and under in Yichang City of Hubei Province from 2019 to 2020. Methods: Based on the Yichang Health Big Data Platform, we investigated cases 20 and under clinically diagnosed as herpes zoster in three hospitals from March 2019 to September 2020. Collecting vesicle fluid and throat swab samples of the cases and completing questionnaires to obtain basic information. Real-time fluorescent quantitative PCR was used for positive identification of the virus. PCR amplification of VZV's open reading frame (ORF) and sequencing of the products to determine the VZV genotype. Analyze mutations at some specific single nucleotide polymorphism (SNP) sites. Results: Among 46 cases of herpes zoster, the male to female ratio was 1.3∶1 (26∶20) and the age ranged from 7 to 20 years old. Fifteen cases had been vaccinated against varicella, including 13 and 2 cases of 1 and 2 doses, respectively. VZV strains were detected in 34 samples (73.91%), all belonging to Clade 2. Phylogenetic tree analysis of the nucleotide of ORF22 showed, compared with Clade 2 referenced strains, the sequence matching degree of nucleotide for all 34 samples was 99.0% to 100.0%. Conclusion: The main VZV strain causing herpes zoster in people aged 20 years and under in Yichang from 2019 to 2020 was Clade 2.

An adult co-presented with varicella and herpes zoster caused by varicella zoster virus genotype J, China: a case report

BackgroundVaricella zoster virus (VZV) causes varicella primarily in childhood, and some rare adults also report varicella. Herpes zoster mainly occurs in adults by endogenous reactivation of latent VZV. Until now, varicella and herpes zoster have seldom been reported simultaneously in one patient. Here, we report a rare case co-presenting with varicella and herpes zoster in a Chinese adult.Case presentationA 44-year-old Chinese man suffered papules and vesicles with pain on the left ear. Five days after onset, he was admitted to the Department of Dermatology of The Third Hospital of Xiamen. Physical examination revealed that small vesicles surrounded by erythema had developed on his trunk, back and neck, and unilateral papules and vesicles in ribbons had also developed on the left ear. This patient was excluded from human immunodeficiency virus and Treponema pallidum infections by ELISA antibody tests. Laboratory tests revealed that the ratio of eosinophils (0.1%) and eosinophil count (0.0 × 109/L) were significantly downregulated. Treatment with valacyclovir, ebastine, mecobalamine, pregabalin and calamine lotion for 5 days was effective therapy for varicella and herpes zoster. Polymerase chain reaction for vesicular fluids from varicella and herpes zoster was positive for VZV, and further phylogenetic analysis and single nucleotide polymorphism variations confirmed that the VZV genotype was type J (clade 2).ConclusionsThis rare case highlights awareness of varicella and herpes zoster caused by VZV infection in adults. Our report provides novel insight into the rare clinical presentation of VZV genotype J.

Genotypes of clinical varicella-zoster virus isolates from Manaus, Brazil.

Vaccination against varicella-zoster virus (VZV) has been effective and safe in countries that routinely administer the vaccine. Brazil began universal VZV vaccination in 2013. This study aimed to identify VZV genotypes present in Manaus, Brazil prior to widespread immunization. Vesicular lesions or cerebral-spinal-fluid samples were collected from patients diagnosed with VZV, herpes zoster, or meningitis/encephalitis. DNA was extracted, amplified, and sequenced. Half the isolates were clade-5 viruses and the remaining were divided between the European clades 1 and 3. This study provides insights into the circulating VZV genotypes in Manaus prior to widespread vaccination.

Genetic analysis of varicella-zoster virus in the aqueous humor in uveitis with severe hyphema

BackgroundGenetic variations have been identified in the genome of varicella-zoster virus (VZV) strains using vesicle fluid, varicella scabs and throat swab samples. We report a rare case of VZV-associated uveitis with severe hyphema, which was immediately diagnosed by polymerase chain reaction (PCR) using the aqueous humor, in which we were able to analyze the VZV genotype for the first time.Case presentationA 16-year-old Japanese boy was referred to our hospital with a 20-day history of unilateral anterior uveitis and 11-day history of hyphema. At presentation, details of the iris, the iridocorneal angle, and the fundus were not visible due to the severe hyphema. Serum anti-VZV IgG and anti-VZV IgM were elevated, and 1.61 × 109 copies/mL of VZV-DNA were detected by real-time PCR using the aqueous humor. As there were no eruptions on his face or body, we diagnosed zoster sine herpete and started intravenous administration of prednisolone and acyclovir. The hyphema completely disappeared 2 weeks after presentation, while sectorial iris atrophy and mild periphlebitis of the fundus became gradually apparent. Anterior inflammation and periphlebitis gradually improved and VZV-DNA in the aqueous humor was reduced to 1.02 × 106 copies/mL at 4 weeks after presentation. Examination by slit lamp microscope revealed no inflammation after 5 months, and VZV-DNA could no longer be detected in the aqueous humor. Serum anti-VZV IgG and anti-VZV IgM also showed a gradual decrease along with improvement in ocular inflammation. The genetic analysis of multiple open reading frames and the R5 variable repeat region in the VZV genes, using DNA extracted from the aqueous humor at presentation, showed that the isolate was a wild-type clade 2 VZV strain (prevalent in Japan and surrounding countries) with R5A allele and one SNP unique to clade 1 (both are major types in Europe and North America).ConclusionsVZV-associated uveitis may develop hyphema that obscures ocular inflammation, thus PCR analysis using the aqueous humor is the key investigation necessary for the diagnosis. The measurement of VZV-DNA copies by real-time PCR would be useful for evaluation of therapeutic effects. We could amplify and analyze VZV genotype using the aqueous humor including a very large number of VZV-DNA copies (1.61 × 109 copies/mL).

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, 22months and 5months 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.

Varicella Zoster Virus Genotyping in Chickenpox Patient’s Clinical Isolates From Iran

Aim: The varicella zoster virus (VZV) causes chickenpox and zoster infections. This study aimed to investigate the distribution of VZV genotypes among Iranian patients. Materials &amp; methods: From 2010 to 2015, 244 patients were enrolled in this cross-sectional study, 45 of whom were positive for VZV DNA. Both direct sequencing and restriction fragment length polymorphism assay were performed for 19 positive specimens. SPSS v.20 was used for statistics. Results: The predominant VZV genotype was M1 (84.2%) followed by genotype E (10.5%) and genotype J (5.3%). Restriction fragment length polymorphism demonstrated that 17 strains were PstI+ BglI+ (M1 and/or J genotypes) and 2 were PstI+ BglI- (E genotype). Conclusion: This research is a prelim study on VZV genotyping. Further investigations will help to confirm the VZV genotype prevalence reported here.

Evolution of Cocirculating Varicella-Zoster Virus Genotypes during a Chickenpox Outbreak in Guinea-Bissau

ABSTRACTVaricella-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.

Varicella zoster virus quantitation in blood from symptomatic and asymptomatic individuals

Primary infection with varicella zoster virus (VZV) occurs in immunocompromised and immunocompetent individuals. Clinical and asymptomatic reactivation with shedding of infectious virus and viremia may occur. The prevalence of VZV viremia is unknown. The aim of this study was to detect VZV viremia and quantify VZV DNA using quantitative polymerase chain reaction (qPCR) in blood from different populations. A qPCR-based method using EvaGreen® was used to quantify VZV DNA in 491 samples, including whole blood, plasma and buffy-coat, from patients hospitalized with varicella-associated disease (Group 1, n=10) and three groups with no VZV disease: individuals with a first clinical diagnosis of central nervous system demyelination (Group 2, n=213) with their age and sex-matched controls (Group 3, n=218); and HIV-infected individuals (Group 4, n=50). VZV-specific IgG antibody titres were measured in Group 3. The proportion positive for viremia and mean detectable VZV DNA load (copies/ml) were: Group 1: 100% (10/10) and 4.6 × 10(6) ± 1.4 × 10(7) ; Group 2: 4% (9/213) and 1.5 × 10(3) ± 1.8 × 10(4) ; Group 3: 8% (17/218) and 1.1 × 10(3) ± 7.8 × 10(3) ; Group 4: 12% (6/50) and 7.7 × 10(1) ± 2.8 × 10(2) . VZV DNA load and IgG titres were not significantly correlated (Group 3 only). VZV load in Group 1 was significantly elevated compared to Groups 2-4 (P<0.001); the latter were not significantly different from each other (P=0.05). VZV genotypes from clades 1-5 were identified in Group 1. VZV DNA was detected but at low frequency and viral load in both immunocompetent and immunocompromised individuals asymptomatic for VZV infection, compared to individuals with active VZV infection.

Research on the genotypes of clinical varicella-zoster virus isolates in Tibet

Objective To analyze the genotypes of clinical varicella-zoster virus(VZV) isolates in Tibet.Methods The samples of vesicular fluid from patients with chickenpox or zoster were collected to isolate VZV in human embryonic fibroblast cells.Furtherly,the isolated VZV were identified by indirect immunofluorescence assay and the positive ones were continuely cultured in vitro to get their genome DNAs.Then,PCR and nucleotide sequencing were performed on the part of open reading frames 1,21,50,54.To confirm the genotypes of isolated virus strains,the gene sequences obtained from PCR products were compared with that in GenBank of VZV Dumas strains,and their restriction enzyme sites were analyzed via Primer 5.0.Results Ten clinical isolates of VZV were obtained from sixteen specimens,the positive isolation rate was 62.5％.Gene analysis showed that among all the ten clinical isolates of VZV in Tibet,three strains are genotype A1,four are genotype A2 and the other three are genotype J1.Conclusion The VZV genotype distribution in Tibet was tightly related to their special geographic locations. Key words: Varicella-zoster virus ; Single nucleotide polymorphism ; Genotype ; Tibet area

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.

GENOTYPING OF VARICELLA-ZOSTER VIRUS (VZV) WILD-TYPE STRAINS ISOLATED IN THE CZECH REPUBLIC

Monitoring of the varicella-zoster virus is becoming an important tool for analysis of the circulation of individual strains of VZV which differ not only at the genomic level, but show a variability in their clinical and epidemiological characteristics. Such data are not available on a large scale from the Czech population and could help understanding the epidemiological and evolutionary characteristics of the virus, as well as its potential for reinfection and increased pathogenesis in the population groups at higher risk for complications. The main aim of this study was detection and monitoring of wild-type or vaccine VZV strain isolates in the region of Eastern Bohemia and genotypic characterization of these isolates. A total of 273 clinical samples were obtained from patients exhibiting symptoms of varicella zoster virus (VZV) infection manifested as chickenpox or herpes zoster (HZ) treated in the Faculty Hospital of Charles University, Medical School in Hradec Kralove, Czech Republic. Characterization of individual short VZV DNA sequences was performed utilizing restriction fragment length polymorphisms (RFLPs), PCR and sequencing. Single nucleotide polymorphisms (SNP) in open reading frames (ORF) 21, 22 and 50 were used to identify individual VZV strains. All clinical isolates (97 from varicella, 176 from herpes zoster) were VZV positive wild-type strains. Sequencing analysis showed that 89 isolates were of the European E1 genotype, 180 were of the European E2 genotype and 2 were identified as the Mosaic M1 strain. In addition, for the first time in this region two unusual genotypes were identified, both representing a combination of E1 and M2 strain specific SNPs. Our prospective VZV genotyping study which is the first to monitor the VZV epidemiological situation in the Czech Republic using such a large set of clinical specimens, has provided valuable epidemiological data and identified two unique VZV recombinants.

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.

Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?

BackgroundVaricella (chickenpox) exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV) infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV) radiation is the major environmental factor driving the molecular evolution of VZV.DiscussionWhile we welcomed the attempt to explain the mechanisms controlling VZV transmission and distribution, we argue that Rice's hypothesis takes lightly the circulation of the so called "temperate VZV genotypes" in tropical regions and, to certain degree, overlooks the predominance of such lineages in certain non-temperate areas. Here, we further discuss and present new information about the overwhelming dominance of temperate VZV genotypes in Mexico regardless of geographical location and climate.SummaryUV radiation does not satisfactorily explain the distribution of VZV genotypes in different tropical and temperate regions of Mexico. Additionally, the cyclic behavior of varicella does not shown significant differences between regions with different climates in the country. More studies should be conducted to identify the factors directly involved in viral spreading. A better understanding of the modes of transmissions exploited by VZV and their effect on viral fitness is likely to facilitate the implementation of preventive measures for disease control.

Immune response of varicella vaccinees to different varicella-zoster virus genotypes

The objective was to verify specific antibody response of varicella vaccinees to varicella-zoster virus (VZV) strains of different major clades and subclades circulating currently in Germany. The neutralization test and the fluorescent antibody to membrane antigen test measuring VZV glycoprotein (gp)-specific antibodies were used as methods. All VZV strains clustering into the main clades 1, 3 and 5 were neutralized by vaccine-induced antibodies and showed specific reaction with VZVgp-specific antibodies of vaccinees. In conclusion, this study provides first experimental evidence that varicella vaccines based on the Japanese Oka strain induce antibody response directed to VZV strains circulating currently in Germany.

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.

Prevalence of varicella-zoster virus genotypes in Australia characterized by high-resolution melt analysis and ORF22 gene analyses

DNA sequence variation analysis has divided varicella-zoster virus (VZV; Human herpesvirus 3) into distinct geographical clades: European, Asian, African and Japanese. These genotypes are becoming increasingly prevalent within regions atypical to their original source and there has been the suggestion of recombination between genotypes. Seventy-eight clinical isolates from hospitalized patients with varicella were collected in New South Wales, the Northern Territory, Western Australia and Victoria from 2006 to 2009. The wild-type strains and the vaccine strain (vOka) were differentiated by single nucleotide polymorphism detection using high-resolution melt analysis of five target genes (ORF1, -21, -37, -60 and -62), and by DNA sequence analysis of a 484 bp region of ORF22. Phylogenetic analysis showed that 46 % (36/78) of the clinical isolates were European clade 1 (C/E1) strains, 21 % (16/78) were European clade 3 (B/E2) strains, 12 % (9/78) were Asian/African clade 5 (A/M1) strains, 10 % (8/78) were clade 4 (J2/M2), 6 % (5/78) were clade 2 (J/J) and 5 % (4/78) belonged to the novel clade VI. No significant association was shown between VZV genotype and region, age or gender. Although European strains were most common, the results suggest an increase in African/Asian, Japanese and clade VI genotypes circulating in Australia.