By analysis of a single, variable, and short DNA sequence of 447 bp located within open reading frame 22 (ORF22), we discriminated three major varicella-zoster virus (VZV) genotypes. VZV isolates from all six inhabited continents that showed nearly complete homology to ORF22 of the European reference strain Dumas were assigned to the European (E) genotype. All Japanese isolates, defined as the Japanese (J) genotype, were identical in the respective genomic region and proved the most divergent from the E strains, carrying four distinct variations. The remaining isolates carried a combination of E-and J-specific variations in the target sequence and thus were collectively termed the mosaic (M) genotype. Three hundred twenty-six isolates collected in 27 countries were genotyped. A distinctive longitudinal distribution of VZV genotypes supports this approach. Among 111 isolates collected from European patients, 96.4% were genotype E. Consistent with this observation, approximately 80% of the VZV strains from the United States were also genotype E. Similarly, genotype E viruses were dominant in the Asian part of Russia and in eastern Australia. M genotype viruses were strongly dominant in tropical regions of Africa, Indochina, and Central America, and they were common in western Australia. However, genotype M viruses were also identified as a minority in several countries worldwide. Two major intertypic variations of genotype M strains were identified, suggesting that the M genotype can be further differentiated into subgenotypes. These data highlight the direction for future VZV genotyping efforts. This approach provides the first simple genotyping method for VZV strains in clinical samples.Varicella-zoster virus (VZV) is a human herpesvirus that commonly causes chicken pox (varicella), usually in young children. Following primary infection a lifelong latent infection is established, and the virus often reactivates in adulthood or senescence to cause shingles (zoster). The VZV genome consists of 125 kb of linear, double-stranded DNA comprising one long and one short unique region, each flanked by inverted repeats (10), and five internal repeat regions (R1 to R5) have been identified. The VZV genome contains at least 71 open reading frames (ORFs), and the functions of many of the proteins they encode have been characterized (10).During the past 2 decades, several groups attempted to evaluate VZV phylogeny. Early efforts in VZV typing used DNA restriction fragment length polymorphism (RFLP) analysis (13,37,38), an approach that confirmed the identity of the VZV strain that causes varicella on primary infection and later reactivates to cause zoster. Relatively consistent restriction enzyme digestion profiles for different VZV strains were observed, providing the first evidence that VZV has a highly conserved genome. Intrastrain variation in restriction enzyme fragment profiles among wild-type VZV isolates was observed (22,36,37). However, the most prominent differences were linked to variation in the number and composi...
In the spring of 2009, a novel influenza A (H1N1) virus emerged in North America and spread worldwide to cause the first influenza pandemic since 1968. During the first 4 months, over 500 deaths in the United States had been associated with confirmed 2009 pandemic influenza A (H1N1) [2009 H1N1] virus infection. Pathological evaluation of respiratory specimens from initial influenza-associated deaths suggested marked differences in viral tropism and tissue damage compared with seasonal influenza and prompted further investigation. Available autopsy tissue samples were obtained from 100 US deaths with laboratory-confirmed 2009 H1N1 virus infection. Demographic and clinical data of these case-patients were collected, and the tissues were evaluated by multiple laboratory methods, including histopathological evaluation, special stains, molecular and immunohistochemical assays, viral culture, and electron microscopy. The most prominent histopathological feature observed was diffuse alveolar damage in the lung in all case-patients examined. Alveolar lining cells, including type I and type II pneumocytes, were the primary infected cells. Bacterial co-infections were identified in >25% of the case-patients. Viral pneumonia and immunolocalization of viral antigen in association with diffuse alveolar damage are prominent features of infection with 2009 pandemic influenza A (H1N1) virus. Underlying medical conditions and bacterial co-infections contributed to the fatal outcome of this infection. More studies are needed to understand the multifactorial pathogenesis of this infection.
Our findings suggest that bacterial pneumonia and cardiac injury contribute to fatal outcomes after infection with influenza B virus and that the frequency of these manifestations may be age related.
Background The coronavirus disease 2019 (COVID-19) pandemic continues to produce substantial morbidity and mortality. To understand the reasons for the wide-spectrum complications and severe outcomes of COVID-19, we aimed to identify cellular targets of SARS-CoV-2 tropism and replication in various tissues. Methods We evaluated RNA extracted from formalin-fixed, paraffin-embedded autopsy tissues from 64 case-patients (age range: 1 month to 84 years; COVID-19 confirmed n=21, suspected n=43) by SARS-CoV-2 RT-PCR. For cellular localization of SARS-CoV-2 RNA and viral characterization, we performed in-situ hybridization (ISH), subgenomic RNA RT-PCR, and whole genome sequencing. Results SARS-CoV-2 was identified by RT-PCR in 32 case-patients (confirmed n=21 and suspected n=11). ISH was positive in 20 and subgenomic RNA RT-PCR was positive in 17 of 32 RT-PCR-positive case-patients. SARS-CoV-2 RNA was localized by ISH in hyaline membranes, pneumocytes and macrophages of lungs, epithelial cells of airways, and in endothelial cells and vessels wall of brain stem, leptomeninges, lung, heart, liver, kidney, and pancreas. D614G variant was detected in 9 RT-PCR-positive case-patients. Conclusions We identified cellular targets of SARS-CoV-2 tropism and replication in the lungs and airways and demonstrated its direct infection in vascular endothelium. This work provides important insights into COVID-19 pathogenesis and mechanisms of severe outcomes.
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