Genotypic Analysis of Varicella-Zoster Virus and Its Seroprevalence in Finland

Abstract

We evaluated the seroprevalence of varicella-zoster virus (VZV) in the Finnish population among various age groups and genetically characterized VZV strains from documented cases of varicella and zoster. VZV-specific immunoglobulin G was measured in 2,842 serum samples that had been submitted for virological studies to the Department of Virology, University of Helsinki, from 1995 to 1996. Specimens for VZV genotyping were obtained from vesicular lesions from two pediatric patients and 26 adult patients. Seroprevalence to VZV varied markedly by age: 45% in children aged <2 months, 12.5% in children aged 6 to 8 months, and >90% in children near 10 years of age, plateauing thereafter into advanced age. The seroprevalence rates indicate that in Finland, as in other countries with temperate climates, primary VZV infection usually occurs during the first decade of life. Twenty-eight VZV DNA-positive specimens were analyzed to identify VZV vaccine and wild-type genotypes. All analyzed specimens were wild type and the European (E) genotype.Varicella zoster virus (VZV) is a common, globally distributed virus that causes chickenpox upon primary infection; it is normally associated with a generalized vesicular rash but may rarely occur without obvious dermal lesions. VZV establishes lifelong latency upon first infection and can reactivate, usually in the elderly, to cause shingles (herpes zoster) (2,12,13,15,34). Patient age is often related to disease severity, with the greatest risk occurring among the very young and very old; immunocompromised persons are also at elevated risk for severe disease (7,11,14). Varicella vaccine use in Finland is currently limited to children with recognized immunosuppression due to leukemia, bone marrow transplant, et cetera. The seroprevalence rate for VZV varies among different populations, and lower prevalence rates have generally been observed in tropical versus temperate climates (9,21,26,27). Over the past 25 years, there has been an evident increase in VZV seroprevalence among children 1 to 4 years of age in the United Kingdom (21). In Finland, VZV has become the agent most frequently associated with central nervous system infections, particularly encephalitis, for all age groups (18,22). Currently, several methods are being used to identify and genotype VZV strains. A variety of methods have been explored for genotyping VZV both to discern strain variation and to discriminate vaccine strains from wild-type isolates (3,4,6,8,10,16,18,23,24,31,36).We developed a novel strategy for VZV genotyping based on the complete sequencing of a short region in open reading frame 22 (ORF22) using material obtained directly from clinical samples (29). By sequencing a collection of 321 contemporary VZV isolates representing multiple countries and six continents, we sorted strains into three discrete geographically associated genotypes: E (European), J (Japanese), and M (mosaic). M strains were dominant in tropical latitudes, and J and E VZV isolates prevail in temperate climate latitudes (29). Genot...

Genotyping of Clinical Varicella-Zoster Virus Isolates Collected in China

“…This genotyping scheme was used to identify variants of VZV circulating in the United Kingdom and seven other countries on four continents (1,2,3). Another genotyping method (9,12,13,15), based on the analysis of a short region (447 bp) in ORF22 and an additional region in either ORF21 or ORF50, was developed and could distinguish five major genotypes (genotypes E1, E2, J, M1, and M2) and two minor genotypes (genotypes M3 and M4). Genotype J strains were the most common in Japan, and genotype E strains were the most common in temperate latitudes.…”

Seroprevalence of varicella zoster virus infection in child and adult population of Catalonia (Spain)

“…In fact, in central and northern European countries, varicella is acquired at earlier ages [14][15][16][17][18][19][20] than in southern European countries [10,[21][22][23][24]. However, climate is probably not the only explanation and other factors, such as those suggested by Breuer [25], may play a role.…”

VZV Molecular Epidemiology

“…Europe (UK, Ireland, Germany, France, Italy, Iceland, Greece, Finland, Spain, Czech Republic, Bulgaria, Albania, Latvia, Lithuania, Russia, Poland, Estonia, Belorussia, Ukraine) (Faga et al 2001;Sauerbrei et al 2003Sauerbrei et al , 2008Wagenaar et al 2003b;Carr et al 2004;Dayan et al 2004;Koskiniemi et al 2007;Loparev et al 2009), America (USA, Canada, Argentina and Brazil) (Faga et al 2001;Muir et al 2002;Wagenaar et al 2003a;Dayan et al 2004;Loparev et al 2004;Peters et al 2006), the Middle East (Morocco, Tunisia) ), Australia and New Zealand (Loparev et al 2007b) have predominantly BglI negative and PstI positive European Clade 1 and 3 strain viruses. In contrast, Japan, Singapore, India, and China have BglI positive nonEuropean Clade 2, 4, and 5 strains (Chow et al 1993;Takada et al 1995;Takayama et al 1996;Faga et al 2001;Wagenaar et al 2003a;Loparev et al 2004;Peters et al 2006;Kaushik et al 2008;Liu et al 2009), while in Africa (Chad, Sudan, DRC, Guinea Bissau, Zambia) Loparev et al 2004) Clade 5 strains predominated (Table 2).…”