Plum pox virus (PPV) is a serious viral threat to stone fruit trees worldwide. Wild Prunus species including American plum (Prunus americana) can serve as sources of inoculum. High-throughput sequencing was used to chara...Plum pox virus (PPV) is a serious viral threat to stone fruit trees worldwide. Wild Prunus species including American plum (Prunus americana) can serve as sources of inoculum. High-throughput sequencing was used to characterize PPV populations in American plum and peach after aphid inoculation and after two cycles of cold-induced dormancy (CID). A significant decrease in the number of sequence variations in the PPV genome was observed after CID in American plum, but not in peach. Seventeen were identified as unique to American plum, while eight were unique to peach. These findings provide insight into the genetic diversity of PPV in a potential reservoir host.
Lett JM, Scussel S, Chéhida SB
… +11 more, Hoareau M, Filloux D, Fernandez E, Roumagnac P, Parvedy E, Quirin E, Clain C, Minatchy J, Roux E, Teycheney PY, Lefeuvre P
Using unbiased high-throughput sequencing for metagenomic screening of viruses in diseased tomato plants, we identified a viral complex that includes viruses previously reported in tomato crops on La Réunion Island as we...Using unbiased high-throughput sequencing for metagenomic screening of viruses in diseased tomato plants, we identified a viral complex that includes viruses previously reported in tomato crops on La Réunion Island as well as a novel polerovirus, tentatively named "tomato necrotic yellowing virus" (ToNYV, proposed species, "Polerovirus ToNYV"). Molecular characterization and phylogenetic analysis revealed that ToNYV is closely related to two recently described poleroviruses from Africa and the Middle East, one of which is transmitted by the whitefly Bemisia tabaci, a trait uncommon among poleroviruses. Our transmission experiments demonstrated that ToNYV is also transmitted by B. tabaci and is prevalent across major tomato-growing regions of La Réunion. These findings highlight the value of metagenomic virome analysis in diseased plants for identifying novel viruses potentially involved in emerging plant diseases, either individually or as components of viral complexes.
A potyvirus (isolate AMLV-CQ) infecting culantro (Eryngium foetidum L.) imported from Vietnam was identified by RT-PCR. The complete genome sequence of AMLV-CQ was determined to be 9,549 nucleotides in length. It contain...A potyvirus (isolate AMLV-CQ) infecting culantro (Eryngium foetidum L.) imported from Vietnam was identified by RT-PCR. The complete genome sequence of AMLV-CQ was determined to be 9,549 nucleotides in length. It contains a large open reading frame encoding a 3,082-amino-acid putative polyprotein, flanked by 5´ and 3´ untranslated regions (UTRs) of 77 and 226 nt, respectively. AMLV-CQ is closely related to five other completely sequenced potyviruses, sharing 68-69% nucleotide and 69-70% amino acid sequence identity. However, the coat protein (CP) gene shares 89% nucleotide and 93% amino acid sequence identity with that of a partially sequenced potyvirus, Ammi majus latent virus (isolate AMLV-WF17). These results suggest that AMLV-CQ and AMLV-WF17 are isolates of the same species. To our knowledge, this is the first report of a complete genome sequence of an AMLV isolate, and culantro was identified as a new natural host for this virus. In addition, a one-step RT-PCR assay was developed that provides a rapid, robust, and highly sensitive approach for the detection of AMLV.
Feline coronavirus (FCoV) has two biotypes: feline enteric coronavirus (FECV), which typically causes mild intestinal infections, and feline infectious peritonitis virus (FIPV), a virulent form associated with a fatal sy...Feline coronavirus (FCoV) has two biotypes: feline enteric coronavirus (FECV), which typically causes mild intestinal infections, and feline infectious peritonitis virus (FIPV), a virulent form associated with a fatal systemic and infectious disease in cats, known as feline infectious peritonitis (FIP). The differentiation between FECV and FIPV has been linked to specific mutations, most notably M1058L and S1060A, in the spike (S) protein. These mutations are believed to enhance macrophage tropism and facilitate systemic dissemination. However, the precise contribution of these mutations to FIPV virulence remains uncertain, as they have also been reported in non-FIP cases. Here, we report three FIP-positive cases (3/20; 15%) in domestic cats in Hanoi, Vietnam, in which the virus carried the M1058L mutation, while none had the S1060A substitution. These findings contribute to the ongoing debate regarding the role of spike protein mutations in FIP pathogenesis and underscore the need for continued genomic surveillance. Further research is needed to elucidate the molecular determinants involved in the FECV-to-FIPV transition, with potential implications for improving diagnosis, treatment, and prevention strategies for feline infectious peritonitis.
Osse de Souza J, Kalita H, Casey C
… +9 more, Larrea-Sarmiento A, Gonzalez-Acuña J, Mueller DS, Sisson AJ, Alabi OJ, Duffeck M, Faris AM, Valmorbida I, Olmedo-Velarde A
The corn leafhopper Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) is a major pest of corn in the Americas, transmitting pathogens that cause corn stunt disease. Using high-throughput sequencing and PCR-bas...The corn leafhopper Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) is a major pest of corn in the Americas, transmitting pathogens that cause corn stunt disease. Using high-throughput sequencing and PCR-based assays, we identified and characterized two novel large-genome pestiviruses (LGPs), chicharrita del maiz pestivirus 1 (ChMPV1) and 2 (ChMPV2), from D. maidis populations collected in Texas, Oklahoma, Missouri, and Iowa. Genome analysis revealed long polyproteins with conserved "Pestiviridae" domains, and virus incidence varied geographically (0-43%). Phylogenetic analysis placed both viruses within the newly proposed family "Pestiviridae". These findings expand the known insect virome and provide tools for future studies on insect virus-vector-plant pathogen interactions.
Human adenovirus (HAdV), a leading cause of pediatric acute respiratory infections (ARIs), exhibited altered transmission patterns during the period of time in which COVID-19 nonpharmaceutical interventions (NPIs) were b...Human adenovirus (HAdV), a leading cause of pediatric acute respiratory infections (ARIs), exhibited altered transmission patterns during the period of time in which COVID-19 nonpharmaceutical interventions (NPIs) were being applied. In this study, we investigated the molecular and clinical characteristics of pediatric HAdV infections in Hangzhou across two epidemiological phases: the 2022 group (March 2022-February 2023), representing a period of strict NPIs with initial post-policy adjustment, and the 2023 group (March 2023-February 2024), reflecting resumption of normal social activities. The retrospective analysis included 55,772 children (aged 0-16 years) with respiratory infections from the Children's Hospital of Zhejiang University School of Medicine. HAdV was detected via PCR‒capillary electrophoresis. Hexon gene sequencing and phylogenetic analysis were performed on 105 randomly selected HAdV-positive samples. In the 2022 group, the positivity rate of HAdV was 4.12% (579/14,049), whereas in the 2023 group, it was 3.59% (1,497/41,723). The peak HAdV infection rate occurred in May 2022 (6.39%, 61/955) and November 2022 (5.32%, 102/1,918). A sustained epidemic trend emerged after Oct. 2023, with a 6.08% (230/3,785) rate occurring in February 2024. HAdV-positive children were predominantly aged 3-6 years (P < 0.001), with no significant difference in the proportion of male and female patients (P > 0.05). The primary coinfections involved Mycoplasma pneumoniae. Pneumonia was the most common clinical diagnosis. Phylogenetic analysis classified 92.6% of the circulating strains as HAdV-B, with a small proportion of HAdV-C. These results offer vital evidence for optimizing the prevention and control of pediatric HAdV infections.
A novel double-stranded RNA (dsRNA) virus was discovered in Valeriana jatamansi Jones plants showing brown necrotic stripe symptoms in Kunming, Yunnan Province. This virus was tentatively designated as "Valeriana jataman...A novel double-stranded RNA (dsRNA) virus was discovered in Valeriana jatamansi Jones plants showing brown necrotic stripe symptoms in Kunming, Yunnan Province. This virus was tentatively designated as "Valeriana jatamansi cryptic virus 2" (VJCV2), with GenBank accession numbers PP482523 and PP482524. The complete genome sequence of VJCV2 was determined using metatranscriptomic sequencing and Sanger sequencing. The genome of VJCV2 comprises two dsRNA segments dsRNA1 (PP482523, 2,463 bp) and dsRNA2 (PP482524, 2,170 bp). dsRNA1 is predicted to encode an RNA-dependent RNA polymerase (RdRp) containing 742 amino acids, and dsRNA2 is predicted to encode a coat protein (CP) with a molecular weight of 75.2 kDa. Multiple sequence alignments revealed that the RdRp and CP encoded by VJCV2 shared a high degree of amino acid sequence similarity with numerous members of the genus Betapartitivirus. Specifically, the RdRp and CP of VJCV2 share the most sequence similarity with dill cryptic virus 2 (77.88% identity in the RdRp and 71.17% in the CP), closely followed by cannabis cryptic virus (77.66% identity in the RdRp and 68.50% in the CP). Phylogenetic trees constructed based on RdRp and CP sequences showed that VJCV2 and its closest relatives clustered independently within the genus Betapartitivirus, and VJCV2 formed a separate small branch together with dill cryptic virus 2 and cannabis cryptic virus. These results indicated that VJCV2 should be classified as a novel member of the genus Betapartitivirus in the family Partitiviridae. This is the first report of a betapartitivirus infecting V. jatamansi.
In this study, we investigated infectious canine hepatitis (ICH), caused by canine adenovirus 1 (CAdV-1), in 125 bear carcasses submitted for examination. CAdV-1 is known to cause severe disease in domestic dogs and in w...In this study, we investigated infectious canine hepatitis (ICH), caused by canine adenovirus 1 (CAdV-1), in 125 bear carcasses submitted for examination. CAdV-1 is known to cause severe disease in domestic dogs and in wild canids and bears. Using molecular and/or histopathological methods, CAdV-1 infection was confirmed in 12 cases: 11 in sloth bears (Melursus ursinus) and one in an Asiatic black bear (Ursus thibetanus). Affected captive bears exhibited acute onset of high fever, jaundice, bloody vomitus, and foul-smelling diarrhoea, followed by death. Necropsy revealed widespread congestion and petechial-to-ecchymotic haemorrhages across multiple visceral organs. Histopathological examination showed marked vascular changes, including engorged blood vessels, oedema, and haemorrhages. Intranuclear basophilic inclusion bodies were observed in endothelial cells, hepatocytes, and Kupffer cells. Immunohistochemistry confirmed the presence of CAdV-1 antigen in endothelial cells of various organs, as well as in hepatocytes and Kupffer cells in the liver. Molecular analysis identified a strain closely related to CAdV-1 isolates previously reported in domestic dogs and other carnivores in various parts of the world. The virus was successfully isolated in MDCK cells from sloth bear samples. Among 99 live sloth bears tested, 41.4% were seropositive for CAdV-1 antibodies. Our findings confirm the susceptibility of these bear species to CAdV-1 and highlight the need for ongoing surveillance, as well as the importance of vaccination in captive bear populations to prevent the spread of this disease.
A new double-stranded RNA mycovirus, tentatively named "Sclerotinia sclerotiorum victorivirus 2" (SsVV2), was isolated from Sclerotinia sclerotiorum strain DT-110. The complete genome of SsVV2 is 5135 nucleotides in leng...A new double-stranded RNA mycovirus, tentatively named "Sclerotinia sclerotiorum victorivirus 2" (SsVV2), was isolated from Sclerotinia sclerotiorum strain DT-110. The complete genome of SsVV2 is 5135 nucleotides in length and contains two open reading frames (ORF1 and ORF2) that overlap at the tetranucleotide AUGA (positions 2546-2549). ORF1 and ORF2 were predicted to encode a coat protein (CP, 755 amino acids) and an RNA-dependent RNA polymerase (RdRP, 836 amino acids), respectively. BLASTp analysis identified Sclerotinia nivalis victorivirus 1 (SnVV1) as the closest match to SsVV2, with their RdRPs sharing 75.7% amino acid sequence identity. Phylogenetic analysis based on the RdRP and CP of victoriviruses further support the clustering of SsVV2 with SnVV1. These results confirm that SsVV2 as a new member of the species Victorivirus nijyusani, genus Victorivirus, family Pseudototiviridae.
Tomato spotted wilt virus (TSWV) is a harmful pathogen that causes severe disease in tomato, pepper, and other horticultural and agronomic crops. Its genome comprises three linear single-stranded RNA molecules (segments...Tomato spotted wilt virus (TSWV) is a harmful pathogen that causes severe disease in tomato, pepper, and other horticultural and agronomic crops. Its genome comprises three linear single-stranded RNA molecules (segments L, M, and S), which are unequally packed in nucleocapsids. Although its genome structure and molecular mechanism of infection are well understood, the evolutionary dynamics of this virus require further analysis to determine the most probable viral ancestor, the date of divergence, the ancestral geographical source of dispersal, and the demographic history of TSWV. For this, we employed a Bayesian framework to analyze whole-genome sequences of 136 isolates of TSWV obtained from different sites worldwide with a sampling window of 35 years, and phylodynamic analysis was performed separately for segments L, M, and S. Our results showed that the mutation rates of the different genome segments ranged from 1.678 × 10 to 2.444 × 10 substitutions/site/year. Although the estimated time to the most recent common ancestor varied depending on the dataset used, the most probable date of TSWV divergence was around 1768 CE. Our phylogeographic analysis yielded concordant results for the three genome segments, indicating that the TSWV population originated in South Korea and, from there, first expanded to Europe and then to North America and other continents. Past population dynamics analysis showed that the virus experienced two major population expansions that coincided with the expansion of the agricultural frontier and the emergence of new species of insect vectors.
Pulkkinen E, Jackson R, Joensuu R
… +11 more, Korhonen EM, Masika MM, Anzala O, Ogola JG, Webala PW, Lunn TJ, Forbes KM, Vapalahti O, Kinnunen T, Sironen T, Jääskeläinen AJ
To enhance preparedness against existing and new zoonotic viruses such as Hendra virus, Nipah virus, and other paramyxoviruses, screening tools and efficient diagnostic methods are needed. Here, we established a conventi...To enhance preparedness against existing and new zoonotic viruses such as Hendra virus, Nipah virus, and other paramyxoviruses, screening tools and efficient diagnostic methods are needed. Here, we established a conventional nested pan-PCR assay using previously described primers for screening of human and bat samples. Additionally, we developed specific real-time RT-PCR (RT-qPCR) assays to detect Nipah virus and Hendra virus genotypes 1 and 2. Both PCR methods demonstrated good performance and could be used for screening of paramyxoviruses. Human serum and cerebrospinal fluid samples from 558 Finnish patients and 60 serum samples from Kenyan patients were screened using the nested-pan-PCR assay, and all were negative. In addition, we screened 340 synanthropic bat samples collected during 2021 and 2023 from Kenya, resulting in the discovery of two parajeilongviruses in Angolan free-tailed bat (Mops condylurus) samples.
Alternaria alternata orfanplasmovirus 1 (AaOrfV1), a previously unreported orfanplasmovirus, was discovered in strain TG155-3 of Alternaria alternata f. sp. mali in this study. The genome of AaOrfV1 consists of two posit...Alternaria alternata orfanplasmovirus 1 (AaOrfV1), a previously unreported orfanplasmovirus, was discovered in strain TG155-3 of Alternaria alternata f. sp. mali in this study. The genome of AaOrfV1 consists of two positive-sense single-stranded RNA segments. RNA1, which is 3122 nucleotides in length, encodes a protein with 973 amino acids. BLASTp analysis showed that this protein had the highest sequence similarity (62.79% identity) to the RNA-dependent RNA polymerase of downy mildew lesion associated orfanplasmovirus 4. RNA2, with a length of 2,485 nucleotides, encodes a protein with 785 amino acids that showed the highest similarity (44.02% identity) to a hypothetical protein of downy mildew lesion associated orfanplasmovirus 7. Phylogenetic analysis indicated that AaOrfV1 clusters with other reported orfanplasmoviruses, supporting its classification as a new member of the proposed family "Orfanplasmoviridae". This is the first report of the complete genome sequence of an orfanplasmovirus from Alternaria alternata f. sp. mali. These findings significantly enhance our understanding of orfanplasmoviruses and the diversity of mycoviruses in A. alternata.
Multidrug-resistant Klebsiella pneumoniae requires alternative therapies. In this study, we characterized two novel phages, PKP K9 (a siphovirus) and PKP Kh11 (a myovirus). Both showed genomic safety and exhibited excell...Multidrug-resistant Klebsiella pneumoniae requires alternative therapies. In this study, we characterized two novel phages, PKP K9 (a siphovirus) and PKP Kh11 (a myovirus). Both showed genomic safety and exhibited excellent reproduction and physicochemical tolerance. A cocktail containing both phages had a broad combined host range (85.7%, 72/84) and showed potent in vitro activity with distinct dose-dependent inhibition modes. In a Galleria mellonella infection model, each phage individually and the two combined provided complete prophylactic and therapeutic protection against lethal challenge. The PKP K9/PKP Kh11 cocktail demonstrates significant therapeutic potential against multidrug-resistant K. pneumoniae.
The order Martellivirales currently comprises seven families of positive-strand (+) RNA viruses, namely, Bromoviridae, Closteroviridae, Endornaviridae, Kitaviridae, Mayoviridae, Togaviridae, and Virgaviridae, that infect...The order Martellivirales currently comprises seven families of positive-strand (+) RNA viruses, namely, Bromoviridae, Closteroviridae, Endornaviridae, Kitaviridae, Mayoviridae, Togaviridae, and Virgaviridae, that infect a range of animals, fungi, and plants. These viruses display remarkably diverse virions built from non-homologous capsid proteins but are unified through homologous alphavirus-like replication module. Here, we introduce an additional family in the order Martellivirales, with the proposed name "Tobaliviridae", to accommodate an emerging group of viruses reported from fungi. This family includes a single genus, "Tobalivirus", with nine species. Tobaliviruses share a capsid protein homologous to those of closteroviruses, potyviruses and alphaflexiviruses, and consistently, some members of the family have been demonstrated to form flexible filamentous virions. The formal taxonomic proposal for the establishment of the family "Tobaliviridae" is awaiting ratification by the International Committee for Taxonomy of Viruses (ICTV).
A novel virus belonging to the genus Victorivirus was identified in the plant-pathogenic fungus Colletotrichum gloeosporioides. Its genome is a double-stranded RNA molecule of 5217 bp containing two open reading frames (...A novel virus belonging to the genus Victorivirus was identified in the plant-pathogenic fungus Colletotrichum gloeosporioides. Its genome is a double-stranded RNA molecule of 5217 bp containing two open reading frames (ORFs). The 5'-proximal ORF (ORF1) encodes a coat protein (CP) consisting of 734 amino acids (aa), whereas the 3'-proximal ORF (ORF2) encodes an RNA-dependent RNA polymerase (RdRp) of 875 aa. The two ORFs overlap at the tetranucleotide sequence AUGA, facilitating a coupled termination-initiation mechanism, which is characteristic of members of the genus Victorivirus. The amino acid sequences of RdRp and CP were found to be most similar (42% and 34% identical, respectively) to those of the Ustilaginoidea virens RNA virus 1. Phylogenetic analysis based on RdRp and CP sequences further supported the placement of this virus within the genus Victorivirus. The genome of this victorivirus, for which we propose the name "Colletotrichum gloeosporioides victorivirus 1" (CgVV1), is 5.2 kb in length and was one of several dsRNA segments identified in the fungal isolate, indicating coinfection with other mycoviruses. To the best of our knowledge, this is the first report of a victorivirus infecting C. gloeosporioides.
In conventional medicinal systems, Ocimum basilicum (OB) is known to be effective against viral infections. A thorough screening of OB's phytoconstituents against Japanese encephalitis virus (JEV) in an in silico and in...In conventional medicinal systems, Ocimum basilicum (OB) is known to be effective against viral infections. A thorough screening of OB's phytoconstituents against Japanese encephalitis virus (JEV) in an in silico and in vitro model has not been documented. Therefore, we used Schrödinger software to do a virtual screening and molecular dynamics simulation (MDS) (100 ns) on 265 phytocompounds from OB against the envelope (E) protein (PDB ID: 3P54) of JEV. Chicoric acid (CA), rutin, and salvianolic acid A (SAA) complexes with the E protein showed outstanding docking scores of -9.136, -9.135, and - 11.838 (kcal/mol), which were all higher than that obtained with the reference compound mycophenolate (-4.481) (kcal/mol). MDS analysis revealed that these compounds, especially CA and rutin, showed comparatively strong stability in the binding pocket of the protein. CA and rutin also exhibited lower binding free energy with this protein than the standard. Moreover, principal component and free energy landscape analysis highlighted the antiviral potential of these compounds against JEV. In vitro experiments demonstrated the antiviral potential of CA and rutin at the early stage of the viral life cycle. These drugs also reduced the levels of proinflammatory cytokines (TNF-α and IL-6) and reactive oxygen species in JEV-infected cells. This study provides insight into the therapeutic potential of CA and rutin as novel drugs against JEV. Additional study is needed to validate their antiviral and neuroprotective activity in an in vivo model of JE.
In China, inpatient/outpatient visits for rotavirus (RV)-associated diarrhea are common among children aged < 5 years. An interim analysis evaluated RV genotype circulation in China in an ongoing observational effectiven...In China, inpatient/outpatient visits for rotavirus (RV)-associated diarrhea are common among children aged < 5 years. An interim analysis evaluated RV genotype circulation in China in an ongoing observational effectiveness study of a pentavalent (RV5) vaccine. Data were collected (October 2020-March 2021) from children eligible for vaccination with three doses of RV5 and receiving treatment for acute gastroenteritis. RV gastroenteritis was reported in 494 (62.1%) of the 796 children tested (median age, 15 months). The circulating genotypes were G9 (81.8%), G2 (5.5%), G8 (4.6%), and G3 (0.4%); no G1 or G4 genotypes were detected. The most common genotype combinations were G9P[8] and G2P[4].
Here, we describe a novel ourmia-like virus, Botryosphaeria dothidea ourmia-like virus 3 (BdOLV3), obtained from the phytopathogenic fungus Botryosphaeria dothidea strain ZM211299-2 infecting apple shoots in Shandong pro...Here, we describe a novel ourmia-like virus, Botryosphaeria dothidea ourmia-like virus 3 (BdOLV3), obtained from the phytopathogenic fungus Botryosphaeria dothidea strain ZM211299-2 infecting apple shoots in Shandong province of China. The genome of BdOLV3 is a positive-sense single-stranded RNA with a length of 2,650 nucleotides (nt), containing a large open reading frame (ORF) that encodes a putative RNA-dependent RNA polymerase (RdRp) consisting of 673 amino acids (aa) with a molecular mass of 75.53 kDa. This RdRp protein contains eight typical conserved motifs associated with ourmia-like viruses. BLASTp analysis revealed that the RdRp protein of BdOLV3 had the highest similarity (61.98%, 61.83%, and 51.47% identity, respectively) to viruses previously identified as Plasmopara viticola lesion associated ourmia-like virus 45, Erysiphe necator associated ourmia-like virus 130, and Magnaporthe oryzae botourmiavirus 7. Phylogenetic analysis based on RdRp sequences indicated that BdOLV3 is a new member of the genus Epsilonscleroulivirus in the family Botourmiaviridae. This is the first report of the complete genomic sequence of a member of the genus Epsilonscleroulivirus found in B. dothidea.
In Japan, only one satsuma dwarf virus (SDV) isolate has been fully sequenced to date. This study provides complete genome sequences of six SDV isolates for which only partial sequences had been determined and three for...In Japan, only one satsuma dwarf virus (SDV) isolate has been fully sequenced to date. This study provides complete genome sequences of six SDV isolates for which only partial sequences had been determined and three for which no sequence data were available. Among all known isolates, nucleotide sequence identity was found to range from 67.9 to 98.6% for RNA1 and from 67.9 to 98.8% for RNA2. The amino acid sequence identity in the coat protein (CP) ranged from 76.9 to 99.2%. Phylogenetic analysis revealed that five of the nine newly sequenced isolates clustered with the citrus mosaic virus (CiMV) strain, two with the SDV strain, and one each with the navel orange infectious mottling virus (NIMV) and hyuganatsu virus (HV) strains.
Typification, the linkage of a name-bearing "type" to a taxon and the description and deposition of a corresponding type specimen, has been a principle of biological taxonomy for over two centuries. It was introduced to...Typification, the linkage of a name-bearing "type" to a taxon and the description and deposition of a corresponding type specimen, has been a principle of biological taxonomy for over two centuries. It was introduced to promote nomenclatural uniformity and stability. Until recently, a modified form of typification was also written in the rules governing the taxonomy of viruses. However, in 2021, the International Committee on Taxonomy of Viruses abolished all type species and removed the requirement to designate a type species when a new genus is created. In this article, I briefly review the history of typification, explain its purpose and evaluate its relevance to current virological practice.