Early Laboratory Preparedness of the Korea Disease Control and Prevention Agency and Response to Unknown Pneumonia Outbreak from Wuhan, China, in January 2020.

We report the response process of the Laboratory Analysis Task Force (LATF) for Unknown Disease Outbreaks (UDOs) at the Korea Disease Control and Prevention Agency (KDCA) during January 2020 to coronavirus disease 2019 (COVID-19), which developed as a UDO in Korea. The advanced preparedness offered by the laboratory diagnostic algorithm for UDOs related to respiratory syndromes was critical for the rapid identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enabled us to establish and expand the diagnostic capacity for COVID-19 on a national scale in a timely manner.

2019 Tabletop Exercise for Laboratory Diagnosis and Analyses of Unknown Disease Outbreaks by the Korea Centers for Disease Control and Prevention.

OBJECTIVES: The Korea Centers for Disease Control and Prevention has published "A Guideline for Unknown Disease Outbreaks (UDO)." The aim of this report was to introduce tabletop exercises (TTX) to prepare for UDO in the future. METHODS: The UDO Laboratory Analyses Task Force in Korea Centers for Disease Control and Prevention in April 2018, assigned unknown diseases into 5 syndromes, designed an algorithm for diagnosis, and made a panel list for diagnosis by exclusion. Using the guidelines and laboratory analyses for UDO, TTX were introduced. RESULTS: Since September 9th, 2018, the UDO Laboratory Analyses Task Force has been preparing TTX based on a scenario of an outbreak caused by a novel coronavirus. In December 2019, through TTX, individual missions, epidemiological investigations, sample treatments, diagnosis by exclusions, and next generation sequencing analysis were discussed, and a novel coronavirus was identified as the causal pathogen. CONCLUSION: Guideline and laboratory analyses for UDO successfully applied in TTX. Conclusions drawn from TTX could be applied effectively in the analyses for the initial response to COVID-19, an ongoing epidemic of 2019 - 2020. Therefore, TTX should continuously be conducted for the response and preparation against UDO.

Genome-Wide Identification and Characterization of Point Mutations in the SARS-CoV-2 Genome.

OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China, in December 2019 and has been rapidly spreading worldwide. Although the causal relationship among mutations and the features of SARS-CoV-2 such as rapid transmission, pathogenicity, and tropism, remains unclear, our results of genomic mutations in SARS-CoV-2 may help to interpret the interaction between genomic characterization in SARS-CoV-2 and infectivity with the host. METHODS: A total of 4,254 genomic sequences of SARS-CoV-2 were collected from the Global Initiative on Sharing all Influenza Data (GISAID). Multiple sequence alignment for phylogenetic analysis and comparative genomic approach for mutation analysis were conducted using Molecular Evolutionary Genetics Analysis (MEGA), and an in-house program based on Perl language, respectively. RESULTS: Phylogenetic analysis of SARS-CoV-2 strains indicated that there were 3 major clades including S, V, and G, and 2 subclades (G.1 and G.2). There were 767 types of synonymous and 1,352 types of non-synonymous mutation. ORF1a, ORF1b, S, and N genes were detected at high frequency, whereas ORF7b and E genes exhibited low frequency. In the receptor-binding domain (RBD) of the S gene, 11 non-synonymous mutations were observed in the region adjacent to the angiotensin converting enzyme 2 (ACE2) binding site. CONCLUSION: It has been reported that the rapid infectivity and transmission of SARS-CoV-2 associated with host receptor affinity are derived from several mutations in its genes. Without these genetic mutations to enhance evolutionary adaptation, species recognition, host receptor affinity, and pathogenicity, it would not survive. It is expected that our results could provide an important clue in understanding the genomic characteristics of SARS-CoV-2.

Kaposi's sarcoma-associated herpesvirus viral protein kinase phosphorylates extracellular signal-regulated kinase and activates MAPK/ERK signaling pathway.

Open reading frame 36 (ORF36) of Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a serine/threonine-type viral protein kinase (vPK). Previous studies have examined the functions of KSHV vPK; however, its role in the activation of extracellular signal-regulated kinase (ERK1/2) has not yet been described to date. Using HEK 293 cell lines, we performed a human phospho-kinase array analysis to screen for MAPK signaling pathways kinases that are activated by KSHV vPK. In addition, we investigated the regulator protein phosphorylation of up/downstream ERK1/2 pathway; nuclear translocation of phosphorylated ERK1/2; and regulation of transcription factor, inflammatory cytokine, and pro-/anti-apoptotic factor by KSHV vPK transfection. Here, we demonstrated that KSHV vPK activates ERK1/2 signaling pathway and plays an important role in the activation of MAPK/ERK signaling pathway.

Aestuariibaculum marinum sp. nov., a marine bacterium isolated from seawater in South Korea.

A Gram-negative, non-motile, aerobic bacterium, designated strain IP7T, was isolated from seawater at the shore of the Incheon Eulwang-ri beach, South Korea. Cells of strain IP7T are straight or slightly rod-shaped and colonies are round, convex and orange-yellow. Strain IP7T is flexirubin-negative, mild halophile, catalase-and oxidase-positive, and produces a yellow-orange carotenoid pigment. Growth is optimal at 30°C, pH 7-9, and 2.0-4.0% NaCl (w/v). On the basis of 16S rRNA gene sequence similarity, strain IP7T is affiliated with genus Aestuariibaculum in the family Flavobacteriaceae, the closest relative being Aestuariibaculum suncheonense SC17T (98.3% sequence similarity). The DNA G + C content of the novel strain is 37.4 mol%. The only quinone is MK-6 menaquinone. Iso-branched C15:0, iso-branched C15:1 G, and iso-branched C17:0 3-OH are major fatty acids. The major polar lipids are phosphatidylethanolamine, an unidentified aminoglycolipid and two unidentified glycolipids. The DNA-DNA hybridization value of strain IP7T with Aestuariibaculum suncheonense SC17T is 28.87%. Based on the collective DNA-DNA hybridization, biochemical, phylogenetic and physiological data, we report a novel species of the genus Aestuariibaculum for which the name Aestuariibaculum marinum sp. nov. is proposed. The type strain is IP7T (= KCTC 52521T = JCM 31725T).

Thalassorhabdus aurantiaca gen. nov., sp. nov., a new member of the family Flavobacteriaceae isolated from seawater in South Korea.

A novel Gram-negative, orange pigmented, strictly aerobic bacterium, designated strain IP9T, was isolated from seawater at the sea shore of Incheon Eulwang-ri beach, South Korea. Cells of strain IP9T were observed to be straight or slightly curved rods and colonies to be round and convex. Strain IP9T was found to be catalase and oxidase positive, and non-motile. Growth was observed in the temperature range of 10-37 °C (optimum at 30 °C), pH range of 6-10 (optimum at pH 7-8) and salt concentration range of 0-7% (w/v) NaCl (optimum at 0-1%). On the basis of 16S rRNA gene sequence similarity and phylogenetic analysis, strain IP9T was found to be related to the members of the family Flavobacteriaceae, being closely related to Hwangdonia seohaensis KCTC 32177T (95.3% sequence similarity). The DNA G + C content of the novel strain was determined to be 39.1 mol%. The major polar lipids were found to be phosphatidylethanolamine, three unidentified aminoglycolipids and two unidentified glycolipids. The major fatty acids (> 10%) were identified as iso-C15:0 and iso-C17:0 3-OH. The predominant quinone was found to be menaquinone 6 (MK-6). Based on the biochemical, phylogenetic and physiological data, we conclude that strain IP9T (= KCTC 52523T = JCM 31732T) represents the type species of a novel genus of the family Flavobacteriaceae for which the name Thalassorhabdus aurantiaca gen. nov., sp. nov. is proposed.

Lysobacter pedocola sp. nov., a novel species isolated from Korean soil.

A Gram-negative, yellow-pigmented bacterial strain, designated IPC6T, was isolated from soil in an arid region of Goyang-si (Gyeonggi-do, South Korea). Cells were strictly aerobic, non-spore-forming, rod-shaped. The strain grew within a temperature range of 10-42°C (optimum, 30°C) and pH of 5.0-11.0 (optimum, pH 8.0) in the presence of 0-2% (w/v) NaCl. Phylogenetically, the novel strain was closely related to members of the Lysobacter genus based on 16S rRNA sequence similarity, and showed the highest sequence similarity to Lysobacter niastensis KACC 11588T (98.5%). The predominant fatty acids were iso-C15:0, iso-C16:0, and summed feature 9 (iso-C17:1ω9c), with Q-8 identified as the major ubiquinone. The polar lipid content included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unknown aminophospholipid, and an unidentified phospholipid. DNA-DNA hybridization results indicated that the strain IPC6T was distinct from Lysobacter niastensis KACC 11588T (37.9 ± 0.14%), Lysobacter panacisoli KACC 17502T (56.4 ± 0.13%), Lysobacter soli KCTC 22011T (8.1 ± 0.04%), Lysobacter gummosus KCTC 12132T (9.6 ± 0.03%), and Lysobacter cavernae KCTC 42875T (37.5 ± 0.14%), respectively. The DNA G + C content of the novel strain was 71.1 mol%. Based on the collective phenotypic, genotypic and chemotaxonomic data, the IPC6T strain is considered to represent a novel species in the genus Lysobacter, for which the name Lysobacter pedocola sp. nov. (= KCTC 42811T = JCM 31020T) is proposed.

Ensifer collicola sp. nov., a bacterium isolated from soil in South Korea.

Strain Mol12T, which presented in the form of Gram-negative, motile, non-spore forming rod-shaped, was isolated from soil in South Korea and characterized to determine its taxonomic position. The strain grew at 20-30°C (optimum 30°C) and pH 7.0-10.0 (optimum pH 8.0) with 1% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain Mol12T was most closely related to Ensifer terangae LMG 7834T (96.78%), Rhizobium daejeonense KCTC 12121T (96.43%), Ensifer adhaerens Casida AT (96.28%). Chemotaxonomic data showed that the predominant fatty acids were Summed Feature 8 (C18:1 ω7c and/or C18:1 ω6c; 53.02%) and C18:1 ω7c 11-methyl (24.01%). Its complex polar lipid contained major amounts of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE) and Q-10 as the predominant ubiquinone. The DNA G+C content of strain Mol12T was determined to be 60.9 mol%. Based on the phylogenetic, chemotaxonomic, and phenotypic data, strain Mol12T (=KCTC 42816T =JCM 31049T) ought to be classified as a type strain of a novel species, for which the name Ensifer collicola sp. nov. is proposed.

Spirosoma areae sp. nov., Isolated from Soil.

A yellow-colored Gram-negative strain, Arct 1-12T, was isolated from a soil sample collected in Seoul Women's University, South Korea, and grown on R2A agar at 25 °C. Growth of strain Arct 1-12T was observed at a temperature range of 15-30 °C (optimal 25 °C), but not at 4 or 42 °C. The strain tolerated up to 1% NaCl (w/v) and displayed optimal growth in the absence of NaCl. Growth occurred at pH 6.0-9.0 (optimally at pH 7). According to the 16S rRNA gene sequence, the strain is moderately related to Spirosoma spitsbergense DSM 19989T (93.54%), S. endophyticum EX36T (93.25%), S. linguale LMG 10896T (92%), S. luteum DSM 19990T (93.16%), S. panaciterrae DSM 21099T (91.09%), S. oryzae RHs22T (90.37%), and S. rigui WPCB118T (91.54%). Chemotaxonomic analyses revealed that strain Arct 1-12T possesses MK-7 as the predominant menaquinone, a polar lipid profile consisting of phosphatidylethanolamine, an unknown aminolipid, an unknown aminophospholipid, and an unknown lipid, and iso-C15:0, C16:1 ω5c and Summed Feature 3 (C16:1 ω6c and/or C16:1 ω7c) as the major fatty acids. The DNA G+C content is 52.3 mol %. Based on polyphasic evidence, strain Arct 1-12T (=JCM 31025 T = KCTC 42814T) is classified as the type strain of a novel Spirosoma species for which the name Spirosoma areae sp. nov. is proposed.

Metagenomic Analysis of Airborne Bacterial Community and Diversity in Seoul, Korea, during December 2014, Asian Dust Event.

Asian dust or yellow sand events in East Asia are a major issue of environmental contamination and human health, causing increasing concern. A high amount of dust particles, especially called as particulate matter 10 (PM10), is transported by the wind from the arid and semi-arid tracks to the Korean peninsula, bringing a bacterial population that alters the terrestrial and atmospheric microbial communities. In this study, we aimed to explore the bacterial populations of Asian dust samples collected during November-December 2014. The dust samples were collected using the impinger method, and the hypervariable regions of the 16S rRNA gene were amplified using PCR followed by pyrosequencing. Analysis of the sequencing data were performed using Mothur software. The data showed that the number of operational taxonomic units and diversity index during Asian dust events were higher than those during non-Asian dust events. At the phylum level, the proportions of Proteobacteria, Actinobacteria, and Firmicutes were different between Asian dust and non-Asian dust samples. At the genus level, the proportions of the genus Bacillus (6.9%), Arthrobacter (3.6%), Blastocatella (2%), Planomicrobium (1.4%) were increased during Asian dust compared to those in non-Asian dust samples. This study showed that the significant relationship between bacterial populations of Asian dust samples and non-Asian dust samples in Korea, which could significantly affect the microbial population in the environment.

Lysobacter humi sp. nov., isolated from soil.

A yellow-pigmented and strictly aerobic bacterial strain, designated FJY8T, was isolated from the soil of Goyang, South Korea. The cells of FJY8T were Gram-reaction-negative, non-motile rods. Colonies were circular, convex and transparent. Strain FJY8T grew optimally at 30 °C, with 0 % (w/v) NaCl and at pH 8. Phylogenetic analysis of the 16S rRNA gene sequence of FJY8T revealed a clear affiliation of this bacterium to the family Lysobacteraceae, and it was related to members of the genus Lysobacter, with Lysobacter xinjiangensis KCTC 22558T being its closest relative (98.7 % sequence similarity). The DNA G+C content was 68.0±0.4 mol%. Diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol were identified as the major polar lipids, and an unidentified phospholipid and two unidentified aminophospholipids were also detected as the minor polar lipids. The major fatty acids were iso-C16 : 0, summed feature 9 (iso-C17 : 1ω9c and/or C16 : 0 10-methyl) and iso-C15 : 0. Only ubiquinone-8 (Q-8) was detected as the isoprenoid quinone. DNA-DNA hybridization values of strain FJY8T with Lysobacter xinjiangensisRCML-52T and Lysobacter mobilis9NM-14T were 55.8±2.0 and 45.2±4.8 %, respectively. On the basis of DNA-DNA hybridization, phylogenetic distinctiveness, and some physiological and biochemical tests, strain FJY8T (=KCTC 42810T=JCM 31019T) represents a novel species of the genus Lysobacter, for which the name Lysobacter humi sp. nov. is proposed.

Alterations in Acetylation of Histone H4 Lysine 8 and Trimethylation of Lysine 20 Associated with Lytic Gene Promoters during Kaposi's Sarcoma-Associated Herpesvirus Reactivation.

Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with formation of Kaposi's sarcoma, multicentric Castleman's disease, and primary effusion lymphoma. Replication and transcription activator (RTA) genes are expressed upon reactivation of KSHV, which displays a biphasic life cycle consisting of latent and lytic replication phases. RTA protein expression results in KSHV genome amplification and successive viral lytic gene expression. Transcriptional activity of viral lytic genes is regulated through epigenetic modifications. In Raji cells latently infected with Epstein-Barr virus, various modifications, such as acetylation and methylation, have been identified at specific lysine residues in histone H4 during viral reactivation, supporting the theory that expression of specific lytic genes is controlled by histone modification processes. Data obtained from chromatin immunoprecipitation and quantitative real-time PCR analyses revealed alterations in the H4K8ac and H4K20me3 levels at lytic gene promoters during reactivation. Our results indicate that H4K20me3 is associated with the maintenance of latency, while H4K8ac contributes to KSHV reactivation in infected TREx BCBL-1 RTA cells.

Alterations in the airborne bacterial community during Asian dust events occurring between February and March 2015 in South Korea.

During Asian dust events, a relatively high concentration of particulate matter is transported by wind from arid and semi-arid regions, such as the Gobi and Taklamakan deserts, to nearby countries, including China, Korea, and Japan. The dust particles contain various microorganisms, which can affect human health as well as the environmental microbe population. In the current study, we investigated the characteristics of the airborne bacterial community during Asian dust events between February and March 2015 in South Korea. Bacterial diversity indexes such as operational taxonomic units, Chao1 and Inverse Simpson index were increased, along with total 16S rRNA gene copy number during Asian dust events. The bacterial community structure during Asian dust events was clearly distinguishable from that during non-Asian dust days. The genera Bacillus and Modestobacter were increased 3.9- and 2.7-fold, respectively, while Escherichia-Shigella was decreased by 89.8%. A non-metric multidimensional scaling plot with metadata analysis revealed association of particulate matter concentration, but not temperature, humidity or wind speed, with bacterial community structure, suggesting that the newly transported dust particles contain various microorganisms that influence the airborne bacterial environment.

Telluribacter humicola gen. nov., sp. nov., a new member of the family Cytophagaceae isolated from soil in South Korea.

A pink-pigmented, gram-negative, non-motile, non-gliding, flexirubin-negative, rod-shaped and strictly aerobic bacterial strain, designated PTR3T, was isolated from a soil sample from Goyang, South Korea. Growth occurred between 10 and 42 °C (optimum 30 °C), 0-4 % (w/v) NaCl (optimum 0 %) and pH 6-9 (optimum 7-8). Phylogenetic analysis based on 16S rRNA sequences showed that strain PTR3T forms a distinct clade with type strains of the closely related genus, Dyadobacter, with similarities of 93.6 and 91.3-93.6 %, respectively. The strain produces a pink carotenoid pigment(s). The major polar lipids are an unidentified aminophospholipid and an aminolipid. Strain PTR3T was found to contain MK-7 as the predominant menaquinone and C16:1 ω7c and/or C16:1 ω6c as the major fatty acids. The DNA G + C content of strain PTR3T was deterrmined to be 45.9 mol %. Based on the chemotaxonomic, phylogenetic and other physiological properties, strain PTR3T (=KCTC 42819T = JCM 31133T) is concluded to represent a novel species in a new genus within the family Cytophagaceae, for which the name Telluribacter humicola gen nov., sp. nov., is proposed.

Thalassiella azotovora gen. nov., sp. nov., a New Member of the Family Kineosporiaceae Isolated from Sea Water in South Korea.

A gram-positive, nonmotile, rod-shaped, nonflagellated, aerobic bacterium, designated strain DSD2(T) was isolated from a seawater sample from Sadong wharf, Ulleung-Island, South Korea. Strain DSD2(T) was found to be able to grow at pH ranging from 6 to 11 (optimum 7-8), 0-7 % (w/v) NaCl (optimum 0 %), at 10-42 °C (optimum 37 °C). 16S rRNA gene sequence analysis revealed that strain DSD2(T) was 95.8 % similar to the type strain of Kineosporia rhamnosa KACC 15195(T), 95.8 % similar to Angustibacter aerolatus KACC 15527(T), and 95.5 % similar to Kineococcus xinjiangensis KCTC 19474(T) as its closest relatives. A neighbor-joining phylogenetic tree based on the 16S rRNA gene sequence showed that strain DSD2(T) related to Micrococcineae and Kineosporiineae suborder clade. The major polar lipids were phosphoglycolipids and phospholipids. Strain DSD2(T) was found to contain MK-8 (H2) and MK-9 (H4) as the predominant menaquinone and iso-C16:0 as the major fatty acid. The isolate contained meso-diaminopimelic acid (meso-A2pm) with alanine, glutamic acid, and glycine as the diagnostic diamino acid. The DNA G+C content of strain DSD2(T) was 73.2 mol%. On the basis of phylogenetic, biochemical, chemotaxonomic, and other physiological characteristics, strain DSD2(T) is assigned to a novel species of a novel genus within the suborder Kineosporiineae and the name Thalassiella azotovora gen nov., sp. nov., is proposed. The type strain is DSD2(T) (= KCTC 39634(T) = JCM 31134(T)).

Rufibacter soli sp. nov., a Bacterium Isolated from Soil.

A gram-negative bacterium, designated FJY1(T), was isolated from a soil sample obtained from a university campus in South Korea. Examination showed that FJY1(T) was red-pigmented, aerobic, motile, and composed of nonspore-forming rods. This strain grew in a temperature range of 15-37 °C and a pH range of 7-9. Based on 16S rRNA gene sequence similarity, strain FJY1(T) was most closely related to Rufibacter roseus H359(T) and Rufibacter tibetensis 1351(T), with sequence similarities of 95.98 and 95.46 %, respectively. Its major cellular fatty acids were iso-C15:0 (18.16 %) and summed feature 4 (C17:1 iso I and C17:1 anteiso B; 15.17 %). The DNA G+C content of FJY1(T) was 49.7 mol%; its predominant quinone was MK-7; and its major polar lipid was phosphatidylethanolamine. Phylogenetic analysis and analysis of its physiological and biochemical characteristics indicated that this isolate constituted a novel species, for which we propose the name Rufibacter soli sp. nov., with the type strain FJY1(T) (=KCTC 42815(T) = JCM 31024(T)).

Deinococcus arenae sp. nov., a novel species isolated from sand in South Korea.

A Gram-negative strain, designated SA1(T), was isolated from a sand specimen from Yangyang Beach, South Korea. The cells of SA1(T) were observed to be red pigmented, strictly aerobic, non-motile rods. Strain SA1(T) was found to grow optimally at 30 °C and pH 7 (pH growth range, pH 7-9). Phylogenetic analyses of the 16S rRNA gene sequence of SA1(T) showed that the organism belongs to the phylum Deinococcus-Thermus and forms a branch within the genus Deinococcus, with Deinococcus actinosclerus BM2(T) as a close relative (99.8   % sequence similarity). The strain was found to be catalase positive and oxidase negative and to metabolise 2-ketogluconate, acetate, D,L-3-hydroxybutyrate, D-glucose, D-maltose, D-mannitol, D-mannose, D-melibiose, D-sorbitol, D-sucrose, glycogen, L-alanine, L-histidine, L-malate, L-proline and n-valerate. The guanine plus cytosine (G + C) base composition of the DNA was 69.5 mol %, as determined by the thermal denaturation method. The predominant respiratory quinone was identified as menaquinone with eight isoprene units (MK-8). The polar lipid profile of strain SA1(T) showed the presence of several unidentified glycolipids, phosphoglycolipids, phospholipids, aminophospholipids and unidentified lipids. In addition, the most abundant fatty acids of strain SA1(T) were identified as C15:1 ω6c, C16:1 ω7c and C17:0. On the basis of phylogenetic analyses, DNA-DNA hybridisation and biochemical characteristics, strain SA1(T) (=KCTC 33741(T) = JCM 31047(T)) is concluded to represent a novel species of the genus Deinococcus, for which the name Deinococcus arenae sp. nov. is proposed.

Analysis of Kaposi's sarcoma-associated herpesvirus latent replication using a real-time polymerase chain reaction technique.

Kaposi's sarcoma-associated herpesvirus (KSHV) undergoes replication independently via latent and lytic pathways. Latent replication is mediated by latent-associated nuclear antigen (LANA), the sole viral trans element for genome maintenance and replication. According to previous studies, LANA tethers the KSHV genome to the host chromosome during latency and interacts with host factors to ensure proper latent replication. Studies using Southern blot experiments have revealed consistently that vector constructs containing the viral terminal repeat (TR) region as a cis element in latent replication are replicated in the presence of LANA. However, Southern blotting is a time-intensive, complicated technique that requires multiple reagents. In addition, it has a limited ability to detect slight changes in replication efficiency under different conditions owing to its relatively low sensitivity. In the current study, a real-time polymerase chain reaction method was developed for detecting transient KSHV replication and was found to be capable of further identifying several factors that affect latent replication. This technique should provide a useful tool for the detection of KSHV latent replication under various conditions, including overexpression of viral or cellular factors and chemical stimulation.

Kaposi΄s sarcoma-associated herpesvirus ORF36 protein induces chromosome condensation and phosphorylation of histone H3.

Kaposi΄s sarcoma-associated herpesvirus (KSHV) has been known as an agent causing Kaposi΄s sarcoma, primary effusion lymphoma, and multicentric Castleman΄s disease. In the lytic phase of the virus cycle, various viral genes are expressed, which causes host cell dysregulation. Among the lytic genes, viral protein kinase (vPK) encoded by ORF36 is a member of serine/threonine protein kinase (CHPK) family, which is involved in viral gene expression, viral DNA replication and encapsidation, and nuclear egress of virions. Recent studies have shown that the BGLF4 protein of Epstein-Barr virus (EBV), a member of the CHPK family, alters the host cell chromatin structure through phosphorylation of its key regulators. The role of KSHV ORF36 in cellular mitotic events, however, is not yet understood. In the current study, we showed that KSHV ORF36 induced chromosome condensation and phosphorylation of histone H3 on Ser 10, which are known as cellular mitosis markers. These processes have occurred in a kinase activity-dependent manner.

Alteration of histone H3 lysine 4 trimethylation on putative lytic gene promoters by human Set1 complex during reactivation of Kaposi's sarcoma-associated herpesvirus.

OBJECTIVE: Histone H3 lysine 4 is trimethylated by the human Set1 complex, which regulates the activation of gene expression. The aim of this study was to identify whether the levels of histone H3 lysine 4 trimethylation (H3K4me3) and the recruitment of human Set1 complex at the promoter regions of lytic genes quantitatively change during reactivation from latent to lytic infection of Kaposi's sarcoma-association herpesvirus (KSHV). METHODS: During KSHV reactivation, global changes of H3K4 methylation in KSHV-infected cells were analyzed by Western blot. The relative levels of association between proteins and promoter regions were determined by chromatin immunoprecipitation assay and quantitative real-time PCR using specific antibodies and primer sets. RESULTS: Our results showed that KSHV reactivation does not alter the overall cellular levels of H3K4 methylation. We observed that the switch from latency to lytic cycle leads to upregulation of H3K4me3 at the active lytic genes. We also found that the recruitment of RNA pol II and subunits of human Set1 complex were enriched at the same regions in response to KSHV reactivation. CONCLUSION: These results demonstrate that the increase of H3K4me3 by human Set1 complex is involved in activation of lytic genes during the lytic infection of KSHV.