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Frontiers in Microbiology 2022The discovery of Acanthamoeba polyphaga mimivirus in 2003 using the free-living amoeba caused a paradigm shift in the virology field. Twelve years later, using another... (Review)
Review
The discovery of Acanthamoeba polyphaga mimivirus in 2003 using the free-living amoeba caused a paradigm shift in the virology field. Twelve years later, using another amoeba as a host, i.e., , novel isolates of giant viruses have been discovered. This amoeba-virus relationship led scientists to study the evolution of giant viruses and explore the origins of eukaryotes. The purpose of this article is to review all the giant viruses that have been isolated from , compare their genomic features, and report the influence of these viruses on the cell cycle of their amoebal host. To date, viruses putatively belonging to eight different viral taxa have been described: 7 are lytic and 1 is non-lytic. The comparison of giant viruses infecting has suggested three homogenous groups according to their size, the replication time inside the host cell, and the number of encoding tRNAs. This approach is an attempt at determining the evolutionary origins and trajectories of the virus; therefore, more giant viruses infecting must be discovered and studied to create a comprehensive knowledge on these intriguing biological entities.
PubMed: 35602053
DOI: 10.3389/fmicb.2022.808499 -
Viruses Apr 2023, so called because of its "mimicking microbe", was discovered in 2003 and was the founding member of the first family of giant viruses isolated from amoeba. These giant... (Review)
Review
, so called because of its "mimicking microbe", was discovered in 2003 and was the founding member of the first family of giant viruses isolated from amoeba. These giant viruses, present in various environments, have opened up a previously unexplored field of virology. Since 2003, many other giant viruses have been isolated, founding new families and taxonomical groups. These include a new giant virus which was isolated in 2015, the result of the first co-culture on . This new giant virus was named "Faustovirus". Its closest known relative at that time was African Swine Fever Virus. Pacmanvirus and Kaumoebavirus were subsequently discovered, exhibiting phylogenetic clustering with the two previous viruses and forming a new group with a putative common ancestor. In this study, we aimed to summarise the main features of the members of this group of giant viruses, including Abalone Asfarvirus, African Swine Fever Virus, Faustovirus, Pacmanvirus, and Kaumoebavirus.
Topics: Swine; Animals; Giant Viruses; Phylogeny; African Swine Fever Virus; Viruses; Mimiviridae; DNA Viruses; Genome, Viral
PubMed: 37112995
DOI: 10.3390/v15041015 -
Frontiers in Microbiology 2021The family was the second family of giant viruses that was described in 2013, after the family . , isolated in 2007 by coculture on , is the prototype member of this... (Review)
Review
The family was the second family of giant viruses that was described in 2013, after the family . , isolated in 2007 by coculture on , is the prototype member of this family. Afterward, the worldwide distribution of marseilleviruses was revealed through their isolation from samples of various types and sources. Thus, 62 were isolated from environmental water, one from soil, one from a dipteran, one from mussels, and two from asymptomatic humans, which led to the description of 67 marseillevirus isolates, including 21 by the IHU Méditerranée Infection in France. Recently, five marseillevirus genomes were assembled from deep sea sediment in Norway. Isolated marseilleviruses have ≈250 nm long icosahedral capsids and 348-404 kilobase long mosaic genomes that encode 386-545 predicted proteins. Comparative genomic analyses indicate that the family includes five lineages and possesses a pangenome composed of 3,082 clusters of genes. The detection of marseilleviruses in both symptomatic and asymptomatic humans in stool, blood, and lymph nodes, and an up-to-30-day persistence of marseillevirus in rats and mice, raise questions concerning their possible clinical significance that are still under investigation.
PubMed: 34149639
DOI: 10.3389/fmicb.2021.648731 -
Virology Journal Jun 2014In 2003, Acanthamoeba polyphaga mimivirus (APMV) was first described and began to impact researchers around the world, due to its structural and genetic complexity. This... (Review)
Review
In 2003, Acanthamoeba polyphaga mimivirus (APMV) was first described and began to impact researchers around the world, due to its structural and genetic complexity. This virus founded the family Mimiviridae. In recent years, several new giant viruses have been isolated from different environments and specimens. Giant virus research is in its initial phase and information that may arise in the coming years may change current conceptions of life, diversity and evolution. Thus, this review aims to condense the studies conducted so far about the features and peculiarities of APMV, from its discovery to its clinical relevance.
Topics: Mimiviridae; Virology
PubMed: 24976356
DOI: 10.1186/1743-422X-11-120 -
Scientific Reports Oct 2022Humans and Acanthamoeba polyphaga mimivirus share numerous homologous genes, including collagens and collagen-modifying enzymes. To explore this homology, we performed a... (Comparative Study)
Comparative Study
Humans and Acanthamoeba polyphaga mimivirus share numerous homologous genes, including collagens and collagen-modifying enzymes. To explore this homology, we performed a genome-wide comparison between human and mimivirus using DELTA-BLAST (Domain Enhanced Lookup Time Accelerated BLAST) and identified 52 new putative mimiviral proteins that are homologous with human proteins. To gain functional insights into mimiviral proteins, their human protein homologs were organized into Gene Ontology (GO) and REACTOME pathways to build a functional network. Collagen and collagen-modifying enzymes form the largest subnetwork with most nodes. Further analysis of this subnetwork identified a putative collagen glycosyltransferase R699. Protein expression test suggested that R699 is highly expressed in Escherichia coli, unlike the human collagen-modifying enzymes. Enzymatic activity assay and mass spectrometric analyses showed that R699 catalyzes the glucosylation of galactosylhydroxylysine to glucosylgalactosylhydroxylysine on collagen using uridine diphosphate glucose (UDP-glucose) but no other UDP-sugars as a sugar donor, suggesting R699 is a mimiviral collagen galactosylhydroxylysyl glucosyltransferase (GGT). To facilitate further analysis of human and mimiviral homologous proteins, we presented an interactive and searchable genome-wide comparison website for quickly browsing human and Acanthamoeba polyphaga mimivirus homologs, which is available at RRID Resource ID: SCR_022140 or https://guolab.shinyapps.io/app-mimivirus-publication/ .
Topics: Acanthamoeba; Collagen; Genomics; Glucose; Glucosyltransferases; Glycosyltransferases; Humans; Mimiviridae; Sugars; Uridine Diphosphate Glucose; Viral Proteins
PubMed: 36207453
DOI: 10.1038/s41598-022-21197-1 -
Journal of Global Antimicrobial... Sep 2022Acanthamoeba keratitis is a severe corneal infection caused by a ubiquitous opportunistic protozoan pathogen known as acanthamoeba. For the last decade, the approach to...
OBJECTIVES
Acanthamoeba keratitis is a severe corneal infection caused by a ubiquitous opportunistic protozoan pathogen known as acanthamoeba. For the last decade, the approach to treating this infection typically includes the use of polyhexamethylene biguanide (0.02%) and/or chlorhexidine (Chx) (0.02%). Although chlorhexidine is reportedly effective, its mode of action towards this type of cell is not clear. The aim of this work was to study the effect of chlorhexidine on the oxidative status of Acanthamoeba polyphaga.
METHODS
The effect of chlorhexidine (Chx) on the oxidative state of Acanthamoeba polyphaga was studied using different antiradical methods including ABTS, DPPH and FRAP and measuring the activity of a couple of antioxidant enzyme namely SOD, NADH-FRD and SDH.
RESULTS
The chlorhexidine was able to induce oxidative imbalance in cells by over expression of reactive oxygen species and/or inhibiting the antioxidant enzymes. In addition to enhancing the antiradical activity in response to oxidative stress, the present drug was able to reduce the activity of two antioxidant enzymes, superoxide dismutase (SOD) and reduced flavin adenine dinucleotide-fumarate reductase (NADH-FRD), to 30% and 40%, respectively.
CONCLUSIONS
We could observe an increase of the antiradical capacity of cell's lysate supernatant, to cope with the overproduction of ROS. The imbalance state The inhibition of both SOD and NADH-FRD activities could have a major role in cell oxidative imbalance.
Topics: Acanthamoeba; Antioxidants; Chlorhexidine; NAD; Oxidative Stress; Superoxide Dismutase
PubMed: 35640869
DOI: 10.1016/j.jgar.2022.05.018 -
PloS One 2022Free-living amoebae (FLA) are gaining attention due to the increasing number of related grave central nervous system (CNS) and sight-threatening eye infections and their...
Isolation and morphological and molecular characterization of waterborne free-living amoebae: Evidence of potentially pathogenic Acanthamoeba and Vahlkampfiidae in Assiut, Upper Egypt.
Free-living amoebae (FLA) are gaining attention due to the increasing number of related grave central nervous system (CNS) and sight-threatening eye infections and their role as Trojan horses for many bacteria and viruses. This study was conducted in Assiut City, Egypt to detect the presence of FLA in different water sources using morphological and molecular approaches and determine their potential pathogenicity. A total of 188 water samples (100 tap, 80 tank, and 8 swimming pool samples) were collected, cultivated on non-nutrient agar seeded with Escherichia coli, and inspected for FLA. Thermo- and osmo-tolerance assays were performed to determine their pathogenicity. Polymerase chain reaction and sequence analysis were performed to confirm the identification and analyze the genotype. Overall, 52 samples (27.7%) were positive for FLA. Of these, 20.7% were identified as Acanthamoeba, 1.6% as Vahlkampfiidae, and 5.3% as mixed Acanthamoeba and Vahlkampfiidae. Seven species of Acanthamoeba were recognized, of which A. triangularis, A. polyphaga, A. lenticulata, and A. culbertsoni are thermo- and osmo-tolerant, and A. astronyxis, A. comandoni, and A. echinulata are non-thermo- and non-osmo-tolerant. The phylogeny analysis revealed T4 and T7 genotypes. Among Vahlkampfiids, 61.5% were identified as thermo- and osmo-tolerant Vahlkampfia, and 30.8% were identified as non-pathogenic Naegleria. One isolate (7.7%) was identified as potentially pathogenic Allovahlkampfia, as confirmed by sequencing. This is the first report documenting the occurrence and phylogeny of waterborne FLA (Acanthamoeba/Vahlkampfiidae) in Assiut, Egypt. The presence of potentially pathogenic FLA highlights the possible health hazards and the need for preventive measures.
Topics: Acanthamoeba; Amoeba; Egypt; Naegleria; Water
PubMed: 35802617
DOI: 10.1371/journal.pone.0267591 -
Frontiers in Cellular and Infection... 2017Viral infection had not been observed for amoebae, until the mimivirus (APMV) was discovered in 2003. APMV belongs to the nucleocytoplasmatic large DNA virus (NCLDV)... (Review)
Review
Viral infection had not been observed for amoebae, until the mimivirus (APMV) was discovered in 2003. APMV belongs to the nucleocytoplasmatic large DNA virus (NCLDV) family and infects not only , but also other professional phagocytes. Here, we review the to give an overview of the current members of the - and families and their structural features during amoebal infection. We summarize the different steps of their infection cycle in . Furthermore, we dive into the emerging field of virophages, which parasitize upon viral factories of the family. The discovery of virophages in 2008 and research in recent years revealed an increasingly complex network of interactions between cell, giant virus, and virophage. Virophages seem to be highly abundant in the environment and occupy the same niches as the and their hosts. Establishment of metagenomic and co-culture approaches rapidly increased the number of detected virophages over the recent years. Genetic interaction of cell and virophage might constitute a potent defense machinery against giant viruses and seems to be important for survival of the infected cell during mimivirus infections. Nonetheless, the molecular events during co-infection and the interactions of cell, giant virus, and virophage have not been elucidated, yet. However, the genetic interactions of these three, suggest an intricate, multilayered network during amoebal (co-)infections. Understanding these interactions could elucidate molecular events essential for proper viral factory activity and could implicate new ways of treating viruses that form viral factories.
Topics: Amoeba; Giant Viruses; Host-Parasite Interactions; Microbial Interactions; Virophages
PubMed: 29376032
DOI: 10.3389/fcimb.2017.00527 -
Scientific Reports Sep 2022Amoebae from the genus Acanthamoeba are important pathogens responsible for severe illnesses in humans such as Acanthamoeba keratitis and granulomatous amoebic...
Amoebae from the genus Acanthamoeba are important pathogens responsible for severe illnesses in humans such as Acanthamoeba keratitis and granulomatous amoebic encephalitis. In the last few decades, AK diagnoses have steadily increased. Most patients suffering from AK were contact lens users and the infection was related to poor hygiene. However, therapy is not yet well established, and treatments may last for several months due to resistance. Moreover, these treatments have been described to generate cytotoxicity. Therefore, there is an urgent need to develop new therapeutic strategies against AK. In this study, the amoebicidal activity of different generation cationic carbosilane dendrons derived with 4-phenylbutyric acid was demonstrated against Acanthamoeba polyphaga and Acanthamoeba griffini trophozoites and cysts. In addition, the combination of chlorhexidine digluconate and the most effective dendron (ArCOG(SNMeI)) showed an in vitro effect against Acanthamoeba trophozoites and cysts, reducing the minimal trophozoite amoebicidal concentration as well as concentrations with cysticidal activity.
Topics: Acanthamoeba; Acanthamoeba castellanii; Amebicides; Animals; Cations; Cysts; Dendrimers; Humans; Phenylbutyrates; Silanes; Trophozoites
PubMed: 36056060
DOI: 10.1038/s41598-022-19200-w -
Infection Ecology & Epidemiology 2015Campylobacter jejuni is a common cause of human bacterial diarrhea in most parts of the world. Most C. jejuni infections are acquired from contaminated poultry, milk,...
BACKGROUND
Campylobacter jejuni is a common cause of human bacterial diarrhea in most parts of the world. Most C. jejuni infections are acquired from contaminated poultry, milk, and water. Due to health care costs and human suffering, it is important to identify all possible sources of infection. Unpasteurized milk has been associated with several outbreaks of C. jejuni infection. Campylobacter has been identified on fresh fruit, and other gastrointestinal pathogens such as Salmonella, E. coli O157:H7 and Cryptosporidium have been involved in fruit juice outbreaks. C. jejuni is sensitive to the acidic environment of fruit juice, but co-cultures with the amoeba, Acanthamoeba polyphaga, have previously been shown to protect C. jejuni at low pH.
METHODS
To study the influence of A. polyphaga on the survival of C. jejuni in milk and juice, the bacteria were incubated in the two products at room temperature and at 4°C with the following treatments: A) C. jejuni preincubated with A. polyphaga before the addition of product, B) C. jejuni mixed with A. polyphaga after the addition of product, and C) C. jejuni in product without A. polyphaga. Bacterial survival was assessed by colony counts on blood agar plates.
RESULTS
Co-culture with A. polyphaga prolonged the C. jejuni survival both in milk and juice. The effect of co-culture was most pronounced in juice stored at room temperature. On the other hand, A. polyphaga did not have any effect on C. jejuni survival during pasteurization of milk or orange juice, indicating that this is a good method for eliminating C. jejuni in these products.
CONCLUSION
Amoebae-associated C. jejuni in milk and juice might cause C. jejuni infections.
PubMed: 26387556
DOI: 10.3402/iee.v5.28675