Icosahedral DNA Research Articles

Modulated Cell Internalization Behavior of Icosahedral DNA Framework with Programmable Surface Modification.

Surface modification could enhance the cell internalization efficiency of nanovehicles for targeted gene or drug delivery. However, the influence of surface modification parameters, including recognition manners, valences, and patterns, is often clouded, especially for the endocytosis of DNA nanostructures in customized shapes. Focusing on an icosahedral DNA framework, we systematically programmed three distinct types of ligands with diverse valence and spatial distribution on their outer surface to study the internalization efficiency, endocytic pathways, and postinternalization fate. The comparison in different aspects of parameters deepens our understanding of the intricate relationship between surface modification and cell entry behavior, offering insights crucial for designing and optimizing DNA framework nanostructures for potent cell-targeted purposes.

Abnormal Changes in IL-13 and IL-17A Serum Levels in Children with Adenovirus Pneumonia and their Diagnostic Value.

Human adenovirus (HAdV) is an enveloped icosahedral DNA virus. HAdV infection can lead to immune system damage, resulting in decreased numbers and compromised function of T cells and B cells. It can also cause an imbalanced Th1/Th2 ratio and dysregulation of pro-inflammatory and anti-inflammatory cytokines. To investigate the serum levels of interleukin (IL)-13 and IL-17A in children with HAdV pneumonia. Pediatric patients diagnosed with HAdV pneumonia were divided into a non-severe group or a severe group based on the severity of their condition. Patients in the severe group were further classified into good and poor prognosis subgroups. We collected 2-2.5 mL of venous blood from each patient, which was then centrifuged. Using an ELISA detection kit, we determined the concentrations of IL-13 and IL-17A. Patients with a severe condition exhibited significantly higher serum concentrations of IL-13 and IL-17A than the non-severe cases. Out of 50 severe cases, 32 had good prognoses, while 18 cases showed poor prognoses. Patients with poor prognoses showed significantly higher serum concentrations of IL-13 compared to those with good prognoses. Serum concentrations of IL-13 and IL-17A are potential diagnostic markers for pediatric patients with severe HAdV pneumonia. Additionally, they demonstrate good predictive value for a poor prognosis in severe pneumonia cases.

Disenfranchised DNA: biochemical analysis of mutant øX174 DNA-binding proteins may further elucidate the evolutionary significance of the unessential packaging protein A.

Most icosahedral DNA viruses package and condense their genomes into pre-formed, volumetrically constrained capsids. However, concurrent genome biosynthesis and packaging are specific to single-stranded (ss) DNA micro- and parvoviruses. Before packaging, ~120 copies of the øX174 DNA-binding protein J interact with double-stranded DNA. 60 J proteins enter the procapsid with the ssDNA genome, guiding it between 60 icosahedrally ordered DNA-binding pockets formed by the capsid proteins. Although J proteins are small, 28-37 residues in length, they have two domains. The basic, positively charged N-terminus guides the genome between binding pockets, whereas the C-terminus acts as an anchor to the capsid's inner surface. Three C-terminal aromatic residues, W30, Y31, and F37, interact most extensively with the coat protein. Their corresponding codons were mutated, and the resulting strains were biochemically and genetically characterized. Depending on the mutation, the substitutions produced unstable packaging complexes, unstable virions, infectious progeny, or particles packaged with smaller genomes, the latter being a novel phenomenon. The smaller genomes contained internal deletions. The juncture sequences suggest that the unessential A* (A star) protein mediates deletion formation.IMPORTANCEUnessential but strongly conserved gene products are understudied, especially when mutations do not confer discernable phenotypes or the protein's contribution to fitness is too small to reliably determine in laboratory-based assays. Consequently, their functions and evolutionary impact remain obscure. The data presented herein suggest that microvirus A* proteins, discovered over 40 years ago, may hasten the termination of non-productive packaging events. Thus, performing a salvage function by liberating the reusable components of the failed packaging complexes, such as DNA templates and replication enzymes.

Deletions of MGF110-9L and MGF360-9L from African swine fever virus are highly attenuated in swine and confer protection against homologous challenge

African swine fever, caused by a large icosahedral DNA virus (African swine fever virus, ASFV), is a highly contagious disease in domestic and feral swine, thus posing a significant economic threat to the global swine industry. Currently, there are no effective vaccines or the available methods to control ASFV infection. Attenuated live viruses with deleted virulence factors are considered to be the most promising vaccine candidates; however, the mechanism by which these attenuated viruses confer protection is unclear. Here, we used the Chinese ASFV CN/GS/2018 as a backbone and used homologous recombination to generate a virus in which MGF110-9L and MGF360-9L, two genes antagonize host innate antiviral immune response, were deleted (ASFV-ΔMGF110/360-9L). This genetically modified virus was highly attenuated in pigs and provided effective protection of pigs against parental ASFV challenge. Importantly, we found ASFV-ΔMGF110/360-9L infection induced higher expression of Toll-like receptor 2 (TLR2) mRNA compared with parental ASFV as determined by RNA-Seq and RT-PCR analysis. Further immunoblotting results showed that parental ASFV and ASFV-ΔMGF110/360-9L infection inhibited Pam3CSK4-triggered activating phosphorylation of proinflammatory transcription factor NF-κB subunit p65 and phosphorylation of NF-κB inhibitor IκBα levels, although NF-κB activation was higher in ASFV-ΔMGF110/360-9L-infected cells compared with parental ASFV-infected cells. Additionally, we show overexpression of TLR2 inhibited ASFV replication and the expression of ASFV p72 protein, whereas knockdown of TLR2 had the opposite effect. Our findings suggest that the attenuated virulence of ASFV-ΔMGF110/360-9L might be mediated by increased NF-κB and TLR2 signaling.

FDA-APPROVED MOLECULAR TESTS USED TO DEFINE HUMAN PAPILLOMAVIRUS (HPV) INFECTIONS WHICH CAUSE CERVIX CANCER

Human papillomavirus (HPV) is a non-enveloped, commonly sexually transmitted virus with icosahedral symmetry and double-stranded circular DNA. Its genome, which is about 8 kb in size, encodes early genes (E1-8) and two late structural capsid genes (L1 and L2). Among the genes that play a role in viral pathogenesis, L1, E6, and E7 genes frequently exist. The E6 and E7 viral genes have a significant role in apoptosis inhibition, viral spread, development of squamous intraepithelial lesion (SIL), cell immortalization, neoplastic transformation, and invasive cancer.
 Demonstration of the relationship between cervical cancer and HPV infections has led to increased interest in this subject and the classification of some HPV genotypes in the high-risk group (HR-HPV) for cervical cancer. Numerous commercial molecular tests have been developed for the identification of HPV genotypes involving different approaches. HPV molecular tests approved by the US Food and Drug Administration (FDA) include Hybrid Capture® 2 (HC2), Cervista™, cobas®, Aptima®, and BD Onclarity™. This article reviews the methodologies, limitations, and commonalities of five FDA-approved tests. The HC2 and Cervista™ tests use non-PCR-based signal amplification methods, while the cobas® and BD Onclarity™ tests use PCR-based target amplification methods. On the other hand, the Aptima® test uses the mRNA transcriptional mediated amplification (TMA) method.
 Each of these methods used in the diagnosis and follow-up of HPV has its strengths and weaknesses. These HPV molecular tests have high sensitivity and specificity. They are also more automated and repeatable than cytological methods. In addition to these advantages, there are also several limitations. Because of these limitations, molecular tests are no more perfect than cytological tests. This situation shows that these tests should not be used alone in the evaluation of HPV infections and cancer identification. On the contrary, HPV test results should be correlated with cytology or biopsy findings.

Three Phages from a Boreal Lake during Ice Cover Infecting Xylophilus, Caulobacter, and Polaromonas Species.

Although the important role of microbes in freshwater is well understood, studies on phage-host systems in such environments during ice cover are completely lacking. Here, we describe the isolation and characterization of three new bacteriophages infecting Xylophilus sp., Caudobacter sp., and Polaromonas sp. from freshwater samples taken under the ice cover of Lake Konnevesi, Finland. Lumi, Kuura, and Tiera bacteriophages have tailed icosahedral virions and double-stranded DNA. Lumi is a siphophage with a genome of 80,496 bp, and Kuura and Tiera are podophages, and their genomes are 43,205 and 45,327 bp in length, resembling viruses in the class Caudoviricetes. Their host ranges were very limited among the winter-isolated bacterial strains from Konnevesi, each infecting only their own hosts. They can infect efficiently at 4 °C, showing that they are adapted to living in lake water under ice cover. Analysis of the viral genome sequences showed that a significant number of the gene products of each virus are unique, indicating that there is unexplored viral diversity in freshwaters. To our knowledge, Lumi and Tiera are the first phages isolated on the Xylophilus sp. and Polaromonas sp. strains, allowing their exploitation in further studies of freshwater bacterial-phage interactions.

An Infectious Virus‐like Particle Built on a Programmable Icosahedral DNA Framework**

AbstractViral genomes can be compressed into a near‐spherical nanochamber to form infectious particles. In order to mimic the virus morphology and packaging behavior, we invented a programmable icosahedral DNA nanoframe with enhanced rigidity and encapsulated the phiX174 bacteriophage genome. The packaging efficiency could be modulated through specific anchoring strands adjustment, and the trapped phage genome remained accessible for enzymatic operations. Moreover, the packed complex could infect Escherichia coli (E. coli) cells through bacterial uptake to produce plaques. This rigid icosahedral DNA architecture demonstrated a versatile platform to develop virus mimetic particles for convenient functional nucleic acid entrapment, manipulation and delivery.

An Infectious Virus-like Particle Built on a Programmable Icosahedral DNA Framework.

Viral genomes can be compressed into a near-spherical nanochamber to form infectious particles. In order to mimic the virus morphology and packaging behavior, we invented a programmable icosahedral DNA nanoframe with enhanced rigidity and encapsulated the phiX174 bacteriophage genome. The packaging efficiency could be modulated through specific anchoring strands adjustment, and the trapped phage genome remained accessible for enzymatic operations. Moreover, the packed complex could infect Escherichia coli (E. coli) cells through bacterial uptake to produce plaques. This rigid icosahedral DNA architecture demonstrated a versatile platform to develop virus mimetic particles for convenient functional nucleic acid entrapment, manipulation and delivery.

Spatially Patterned Neutralizing Icosahedral DNA Nanocage for Efficient SARS-CoV-2 Blocking.

Broad-spectrum anti-SARS-CoV-2 strategies that can inhibit the infection of wild-type and mutant strains would alleviate their threats to global public health. Here, we propose an icosahedral DNA framework for the assembly of up to 30 spatially arranged neutralizing aptamers (IDNA-30) to inhibit viral infection. Each triangular plane of IDNA-30 is composed of three precisely positioned aptamers topologically matching the SARS-CoV-2 spike trimer, thus forming a multivalent spatially patterned binding. Due to its multiple binding sites and moderate size, multifaced IDNA-30 induces aggregation of viruses. The rigid icosahedron framework afforded by four helixes not only forms a steric barrier to prevent the virus from binding to the host but also limits the conformational transformation of the SARS-CoV-2 spike trimer. Combining multivalent topologically patterned aptamers with structurally well-defined nanoformulations, IDNA-30 exhibits excellent broad-spectrum neutralization against SARS-CoV-2, including almost completely blocking the infection of Omicron pseudovirus. Overall, this multidimensional neutralizing strategy provides a new direction for the assembly of neutralizing reagents to enhance their inhibitory effect against SARS-CoV-2 infection and combat other disease-causing viruses.

Low-Temperature Adaptation Targets Genome Packing Reactions in an Icosahedral Single-Stranded DNA Virus

øX174, G4, and α3 represent the three sister genera of a Microviridae subfamily. α3-like genomes are considerably larger than their sister genera genomes, yet they are packaged into capsids of similar internal volumes. They also contain multiple A* genes, which are nested within the larger A gene reading frame. Although unessential under most conditions, A* proteins mediate the fidelity of packaging reactions. Larger genomes and multiple A* genes may indicate that genome packaging is more problematic for α3-like viruses, especially at lower temperatures, where DNA persistence lengths would be longer. Unlike members of the other genera, which reliably form plaques at 20°C, α3-like phages are naturally cold sensitive below 28°C. To determine whether there was a connection between the uniquely α3-like genome characteristics and the cold-sensitive phenotype, the α3 assembly pathway was characterized at low temperature. Although virions were not detected, particles consistent with off-pathway packaging complexes were observed. In a complementary evolutionary approach, α3 was experimentally evolved to grow at progressively lower temperatures. The two major responses to cold adaptation were genome reduction and elevated A* gene expression. IMPORTANCE The production of enzymes, transcription factors, and viral receptors directly influences the niches viruses can inhabit. Some prokaryotic hosts can thrive in widely differing environments; thus, physical parameters, such as temperature, should also be considered. These variables may directly alter host physiology, preventing viral replication. Alternatively, they could negatively inhibit infection processes in a host-independent manner. The members of three sister Microviridae genera (canonical species øX174, G4 and α3) infect the same host, but α3-like viruses are naturally cold sensitive, which could effectively exclude them from low-temperature environments (<28°C). Exclusion appeared to be independent of host cell physiology. Instead, it could be largely attributed to low-temperature packaging defects. The results presented here demonstrate how physical parameters, such as temperature, can directly influence viral diversification and niche determination in a host-independent manner.

Molecular Landscape and Computational Screening of the Natural inhibitors against HPV16 E6 Oncoprotein.

Background:Human Papillomavirus (HPV) is a small, non-enveloped, icosahedral and double-stranded DNA virus with a genome of 8 kb, belonging to the papillomaviridae family. HPV has been associated with 99.7% cases of cervical squamous cell carcinoma worldwide. The HPV E6 protein is known as a potent oncogene and is closely allied with the events that result in the malignant transformation of virally infected cells. Objective:The present study aims to target plant derived anticancer molecules for HPV driven cancer using a computational approach. Methods: In this study, E6 oncoprotein was targeted by 101 plant-derived nutraceuticals using the molecular docking method. The multiple sequence analysis and phylogenetic analysis of low risk and high risk 28 HPV E6 proteins were performed. Results:Withanolide D, Ginkgetin, Theaflavin, Hesperidin, and Quercetin-3-gluconide were identified as the potential inhibitors of HPV 16 E6 protein. The zinc finger domain was identified on all variants of HPV E6 oncoprotein while high-risk HPV18, HPV31, HPV33, HPV35, HPV39, HPV45, HPV58, HPV68 and HPV73: probable risk HPV53 and low-risk HPV43 and HPV70 contain PDZ domain. Conclusion:The current study using bioinformatics analysis approaches reveals a promising platform for developing anti-cancerous competitive inhibitors targeting HPV.

HPV sketch of its lifestyle

Human papillomaviruses (HPV) are small icosahedral DNA non-enveloped viruses, adapted to human beings from the very beginning, since the apparition of the first humanoids. They are part of the large papillomaviruses group, which co-evolved with the first reptile species, around 350 million years ago. These viruses persist for years and even decades together with their animal or human hosts, in epithelial cells and/or mucosae, being considered rather commensal or producing chronic unapparent “infections” in most cases. There are described more than 150 HPV species, included in Alpha, Beta, Gamma, and some in Miu and Niu genera. The mechanisms of co-evolution between the human host and HPV are complex and depend on the host immune tolerance (with unknown advantages from HPV, to be tolerated) and HPV replication, with the promotion of host epithelial cell persistence, which in the case of HPV species with ma­lig­nant risk could cause an “immortality” of the host-cell and consequently malignancy. The mucosal-associated HPV lesions, condyloma acuminatum and focal epithelial hy­per­plasia, are benign lesions caused by types of HPV with mucosal affinities. Other lesions are malignant, such as cervical or other anogenital cancers (of vulva, vagina, pe­nis and anus) and head and neck cancers. The HPV spe­cies associated with cancers are included mostly in Alpha HPV genus. Cutaneous associated HPV lesions – common warts, plantar warts, flat warts, filiform warts, pigmented warts, epidermoid cysts – are benign lesions associated with cutaneous HPV strains, but Bowen disease is a type of skin cancer associated with alpha HPV. There are also sug­ges­tions that some of non-melanoma skin cancers could be as­sociated with some beta HPVs. Curative measures in­clude to­pi­cal cytotoxic and antiviral agents, topical im­mu­no­mo­du­la­tory agents, intralesional immunotherapy, destructive me­thods and surgery. Vaccination is the only way to de­crease the incidence of HPV-induced cancers and should be in­di­ca­ted for both boys and girls before natural infection oc­curs.

Beta Human Papillomavirus and Merkel Cell Polyomavirus in Skin Neoplasms

Beta Human Papillomavirus and Merkel Cell Polyomavirus in Skin Neoplasms

Crystal Structure of African Swine Fever Virus pS273R Protease and Implications for Inhibitor Design.

African swine fever (ASF) is a highly contagious hemorrhagic viral disease of domestic and wild pigs that is responsible for serious economic and production losses. It is caused by the African swine fever virus (ASFV), a large and complex icosahedral DNA virus of the Asfarviridae family. Currently, there is no effective treatment or approved vaccine against the ASFV. pS273R, a specific SUMO-1 cysteine protease, catalyzes the maturation of the pp220 and pp62 polyprotein precursors into core-shell proteins. Here, we present the crystal structure of the ASFV pS273R protease at a resolution of 2.3 Å. The overall structure of the pS273R protease is represented by two domains named the "core domain" and the N-terminal "arm domain." The "arm domain" contains the residues from M1 to N83, and the "core domain" contains the residues from N84 to A273. A structure analysis reveals that the "core domain" shares a high degree of structural similarity with chlamydial deubiquitinating enzyme, sentrin-specific protease, and adenovirus protease, while the "arm domain" is unique to ASFV. Further, experiments indicated that the "arm domain" plays an important role in maintaining the enzyme activity of ASFV pS273R. Moreover, based on the structural information of pS273R, we designed and synthesized several peptidomimetic aldehyde compounds at a submolar 50% inhibitory concentration, which paves the way for the design of inhibitors to target this severe pathogen.IMPORTANCE African swine fever virus, a large and complex icosahedral DNA virus, causes a deadly infection in domestic pigs. In addition to Africa and Europe, countries in Asia, including China, Vietnam, and Mongolia, were negatively affected by the hazards posed by ASFV outbreaks in 2018 and 2019, at which time more than 30 million pigs were culled. Until now, there has been no vaccine for protection against ASFV infection or effective treatments to cure ASF. Here, we solved the high-resolution crystal structure of the ASFV pS273R protease. The pS273R protease has a two-domain structure that distinguishes it from other members of the SUMO protease family, while the unique "arm domain" has been proven to be essential for its hydrolytic activity. Moreover, the peptidomimetic aldehyde compounds designed to target the substrate binding pocket exert prominent inhibitory effects and can thus be used in a potential lead for anti-ASFV drug development.

Regions of bovine adenovirus-3 IVa2 involved in nuclear/nucleolar localization and interaction with pV

Bovine adenovirus-3 (BAdV-3) is a non enveloped, icosahedral DNA virus containing a genome of 34446 bps. The intermediate region of BAdV-3 encodes pIX and IVa2 proteins. Here, we report the characterization of BAdV-3 IVa2. Anti-IVa2 serum detected a 50 kDa protein at 24–48 h post infection in BAdV-3 infected cells. The IVa2 localizes to nucleus and nucleolus of BAdV-3 infected cells. Analysis of mutant IVa2 demonstrated that amino acids 1–25 and 373–448 are required for nuclear and nucleolar localization of IVa2, respectively. The nuclear import of IVa2 utilize importin α -1 of importin nuclear import pathway. Although deletion/substitution of amino acids 4–18 is sufficient to abrogate the nuclear localization of IVa2, amino acids 1–25 are required for nuclear localization of a cytoplasmic protein. Furthermore, we demonstrate that amino acids 1–25 and 120–140 of IVa2 interact with importin α-1 and pV proteins, respectively in BAdV-3 infected cells.

A Novel Packing for A-Form DNA in an Icosahedral Virus

Studies on viruses infecting archaea living in the most extreme environments continue to show a remarkable diversity of structures, suggesting that the sampling continues to be very sparse. We have used electron cryo-microscopy (cryo-EM) to study at 3.7 Å resolution the structure of the Sulfolobus polyhedral virus 1 (SPV1) which was originally isolated from a hot, acidic spring in Beppu, Japan. The two capsid proteins with variant single jelly-roll folds form pentamers and hexamers which assemble into a T=43 icosahedral shell. In contrast to tailed icosahedral double-stranded DNA (dsDNA) viruses infecting bacteria and archaea, and herpesviruses infecting animals and humans, where naked DNA is packed under very high pressure due to the repulsion between adjacent layers of DNA, the circular dsDNA in SPV1 is fully covered with a viral protein forming a nucleoprotein filament with attractive interactions between layers. Most strikingly, we have been able to show that the DNA is in an A-form, as it is in the filamentous viruses infecting hyperthermophilic acidophiles. While previous studies have suggested that DNA is in the B-form in bacteriophages, we believe that this is the first direct visualization of the structure of DNA in an icosahedral virus.

Isolation of Yasminevirus, the First Member of Klosneuvirinae Isolated in Coculture with Vermamoeba vermiformis, Demonstrates an Extended Arsenal of Translational Apparatus Components.

The family of giant viruses is still expanding, and evidence of a translational machinery is emerging in the virosphere. The Klosneuvirinae group of giant viruses was first reconstructed from in silico studies, and then a unique member was isolated, Bodo saltans virus. Here we describe the isolation of a new member in this group using coculture with the free-living amoeba Vermamoeba vermiformis This giant virus, called Yasminevirus, has a 2.1-Mb linear double-stranded DNA genome encoding 1,541 candidate proteins, with a GC content estimated at 40.2%. Yasminevirus possesses a nearly complete translational machinery, with a set of 70 tRNAs associated with 45 codons and recognizing 20 amino acids (aa), 20 aminoacyl-tRNA synthetases (aaRSs) recognizing 20 aa, as well as several translation factors and elongation factors. At the genome scale, evolutionary analyses placed this virus in the Klosneuvirinae group of giant viruses. Rhizome analysis demonstrated that the genome of Yasminevirus is mosaic, with ∼34% of genes having their closest homologues in other viruses, followed by ∼13.2% in Eukaryota, ∼7.2% in Bacteria, and less than 1% in Archaea Among giant virus sequences, Yasminevirus shared 87% of viral hits with Klosneuvirinae. This description of Yasminevirus sheds light on the Klosneuvirinae group in a captivating quest to understand the evolution and diversity of giant viruses.IMPORTANCE Yasminevirus is an icosahedral double-stranded DNA virus isolated from sewage water by amoeba coculture. Here its structure and replicative cycle in the amoeba Vermamoeba vermiformis are described and genomic and evolutionary studies are reported. This virus belongs to the Klosneuvirinae group of giant viruses, representing the second isolated and cultivated giant virus in this group, and is the first isolated using a coculture procedure. Extended translational machinery pointed to Yasminevirus among the quasiautonomous giant viruses with the most complete translational apparatus of the known virosphere.

A packing for A-form DNA in an icosahedral virus

Studies on viruses infecting archaea living in the most extreme environments continue to show a remarkable diversity of structures, suggesting that the sampling continues to be very sparse. We have used electron cryo-microscopy to study at 3.7-Å resolution the structure of the Sulfolobus polyhedral virus 1 (SPV1), which was originally isolated from a hot, acidic spring in Beppu, Japan. The 2 capsid proteins with variant single jelly-roll folds form pentamers and hexamers which assemble into a T = 43 icosahedral shell. In contrast to tailed icosahedral double-stranded DNA (dsDNA) viruses infecting bacteria and archaea, and herpesviruses infecting animals and humans, where naked DNA is packed under very high pressure due to the repulsion between adjacent layers of DNA, the circular dsDNA in SPV1 is fully covered with a viral protein forming a nucleoprotein filament with attractive interactions between layers. Most strikingly, we have been able to show that the DNA is in an A-form, as it is in the filamentous viruses infecting hyperthermophilic acidophiles. Previous studies have suggested that DNA is in the B-form in bacteriophages, and our study is a direct visualization of the structure of DNA in an icosahedral virus.

Fifteen Marseilleviruses Newly Isolated From Three Water Samples in Japan Reveal Local Diversity of Marseilleviridae

The family Marseilleviridae, defined as a group of icosahedral double-stranded DNA viruses with particle size of approximately 250 nm and genome size of 350–380 kbp, belongs to the nucleo-cytoplasmic family of large DNA viruses. The family Marseilleviridae is currently classified into lineages A–E. In this study, we isolated 12 or 15 new members of the family Marseilleviridae from three sampling locations in Japan. Molecular phylogenetic analysis of the MCP genes showed that the new viruses could be further classified into three groups, hokutoviruses, kashiwazakiviruses, and kyotoviruses. Hokutoviruses were closely related to lineage B, kyotoviruses were related to lineage A, and kashiwazakiviruses were also classified into lineage B but a new putative subgroup of lineage B, revealing the diversity of this lineage. Interestingly, more than two viruses with slightly different MCP genes were isolated from a single water sample from a single location, i.e., two hokutoviruses and one kashiwazakivirus were isolated from a small reservoir, five kashiwazakiviruses from the mouth of a river, and five kyotoviruses from fresh water of a river, suggesting that several milliliters of water samples contain several types of giant viruses. Amoeba cells infected with hokutoviruses or kashiwazakiviruses exhibited a “bunch” formation consisting of normal and infected cells similarly to a tupanvirus, whereas cells infected with kyotoviruses or tokyovirus did not. These results suggest the previously unrecognized local diversity of the family Marseilleviridae in aquatic environments.

Chicken anemia virus: A deadly pathogen of poultry.

Chicken infectious anemia (CIA) is an immunosuppressive disease that causes great economic loss in poultry industry globally. This disease is caused by chicken anemia virus (CAV), an icosahedral and single-stranded DNA virus that is transmitted both vertically and horizontally. CAV, which belongs to the genus Gyrovirus has been reported in human, mouse and dog feces. Rapid identification of different strains of gyrovirus with high similarity to CAV has heightened public concern on this virus. Clinical symptoms of this disease such as intramuscular hemorrhage, weight loss, anemia and bone marrow aplasia are prominent in young chickens, while adult chickens experience subclinical symptoms. Biosecurity measures such as good management practice and vaccination have been the most reliable control strategy against this virus. Therefore, this study reviews the current state of CAV under the following subheadings (i) Chicken anemia virus (ii) Pathogenesis of CAV (iii) Serological evaluation of host antibodies to CAV (iv) Association of Marek's disease and infectious bursa disease with CAV infection (v) Genetic diversity and phylogenetics of CAV strains (vi) Current and future vaccine strategy in the control of CAV. In conclusion, improvement on DNA and recombinant vaccines strategy could curtail the economic impact of CAV on poultry birds. Keywords: adjuvant; CAV; chicken; disease.