siphoviridae siphoviridae siphoviridae is a family of double-stranded dna viruses in the order caudovirales. bacteria and archaea serve as natural hosts. there are 1,166 species in this family, assigned to 366 genera and 22 subfamilies. the characteristic structural features of this family are a nonenveloped head and noncontractile tail. siphoviridae tme picture of an escherichia virus hk97 virion, siphoviridae virus classification (unranked): virus realm: duplodnaviria kingdom: heunggongvirae phylum: uroviricota class: caudoviricetes order: caudovirales family: siphoviridae genera see text synonyms styloviridae structure typical structure of a siphovirus viruses in siphoviridae are non-enveloped, with icosahedral and head-tail geometries (morphotype b1) or a prolate capsid (morphotype b2), and t=7 symmetry. the diameter is around 60 nm. members of this family are also characterized by their filamentous, cross-banded, noncontractile tails, usually with short terminal and subterminal fibers. genomes are double stranded and linear, around 50 kb in length, containing about 70 genes. the guanine/cytosine content is usually around 52%. life cycle viral replication is cytoplasmic. entry into the host cell is achieved by adsorption into the host cell. replication follows the replicative transposition model. dna-templated transcription is the method of transcription. translation takes place by -1 ribosomal frameshifting, and +1 ribosomal frameshifting. the virus exits the host cell by lysis, and holin/endolysin/spanin proteins. bacteria and archaea serve as the natural host. transmission routes are passive diffusion. taxonomy electron micrographs of siphovirus from cutibacterium acnes (formerly propionibacterium acnes). phages were negatively stained and subjected to transmission electron microscopy. the phages have a head of approximately 55 nm in diameter, loaded with genetic material. their tails have a size of 150 × 10 nm and are flexible and non-contractile. in the lower micrograph, pad25 is adhering to bacterial cell debris, and two phages have lost their heads. all phages were classified as siphoviruses based on their morphology. the following subfamilies are recognized: arquatrovirinae arquatrovirus camvirus likavirus azeredovirinae dubowvirus phietavirus bclasvirinae acadianvirus coopervirus pregunavirus pipefishvirus rosebushvirus bronfenbrennervirinae biseptimavirus peevelvirus chebruvirinae brujitavirus dclasvirinae hawkeyvirus plotvirus deejayvirinae kenoshvirus secretariavirus tanisvirus dolichocephalovirinae berteleyvirus colossusvirus poidextervirus spirovirus gochnauervirinae dragolirvirus harrisonvirus vegavirus wandersvirus guernseyvirinae cornelivirus jerseyvirus kagunavirus gutmannvirinae carmenvirus pobcunavirus hendrixvirinae brynievirus cauhtlivirus kwaitsingvirus nochtlivirus sainkungvirus shamshuipovirus wainchavirus wongtaivirus yautsimvirus langleyhallvirinae getalongvirus horusvirus phystavirus mccleskeyvirinae limdunavirus unaquatrovirus mclasvirinae bongovirus reyvirus nclasvirinae bettesrvirus charlievirus redivirus nymbaxtervirinae baxtervirus nymphaduravirus pclasvirinae bignuzvirus fisburnevirus phayoncevirus queuovirinae amoyvirus nipunavirus nonagvirus seuratvirus skryabinvirinae bambunaquatrovirus puchinovirus trabyvirinae jelitavirus slepowrronvirus tybeckvirinae douglasvirus lenusvirus lideunavirus maenadvirus the following genera are unassigned to a subfamily: abbeymikolonvirus abidjanvirus agmunavirus aguilavirus ahduovirus alachuavirus alegriavirus amigovirus anatolevirus andrewvirus andromedavirus annadreamyvirus appavirus apricotvirus arawnvirus armstrongvirus ashduovirus attisvirus attoomivirus audreyjarvisvirus austintatiousvirus avanivirus bantamvirus barnyardvirus beceayunavirus beetrevirus behunavirus bernalvirus betterkatzvirus bievrevirus bingvirus bowservirus bridgettevirus britbratvirus bronvirus brussowvirus camtrevirus casadabanvirus cbastvirus cecivirus ceduovirus ceetrepovirus cequinquevirus chenonavirus cheoctovirus chertseyvirus chivirus chunghsingvirus cimpunavirus cinunavirus coetzeevirus colunavirus coralvirus corndogvirus cornievirus coventryvirus cronusvirus cukevirus daredevilvirus decurrovirus delepquintavirus demosthenesvirus detrevirus deurplevirus dhillonvirus dinavirus dismasvirus doucettevirus edenvirus efquatrovirus eiauvirus eisenstarkvirus elerivirus emalynvirus eyrevirus fairfaxidumvirus farahnazvirus fattrevirus feofaniavirus fernvirus fibralongavirus fowlmouthvirus franklinbayvirus fremauxvirus fromanvirus gaiavirus galaxyvirus galunavirus gamtrevirus gesputvirus getseptimavirus ghobesvirus gilesvirus gillianvirus gilsonvirus glaedevirus godonkavirus goodmanvirus gordonvirus gordtnkvirus gorganvirus gorjumvirus gustavvirus halcyonevirus hattifnattvirus hedwigvirus helsingorvirus hiyaavirus hnatkovirus holosalinivirus homburgvirus hubeivirus iaduovirus ikedavirus ilzatvirus incheonvirus indlulamithivirus inhavirus jacevirus jarrellvirus jenstvirus jouyvirus juiceboxvirus junavirus kairosalinivirus kamchatkavirus karimacvirus kelleziovirus kilunavirus klementvirus knuthellervirus kojivirus konstantinevirus korravirus kostyavirus krampusvirus kryptosalinivirus kuleanavirus labanvirus lacnuvirus lacusarxvirus lafunavirus lambdavirus lambovirus lanavirus larmunavirus laroyevirus latrobevirus leicestervirus lentavirus liebevirus liefievirus lillamyvirus lokivirus lomovskayavirus luckybarnesvirus luckytenvirus lughvirus lwoffvirus magadivirus majavirus manhattanvirus mapvirus mardecavirus marienburgvirus marvinvirus maxrubnervirus mementomorivirus metamorphoovirus minunavirus moineauvirus montyvirus mudcatvirus mufasoctovirus muminvirus murrayvirus nanhaivirus nazgulvirus neferthenavirus nesevirus nevevirus nickievirus nonanavirus nyceiraevirus oengusvirus omegavirus oneupvirus orchidvirus oshimavirus pahexavirus pamexvirus pankowvirus papyrusvirus patiencevirus pepyhexavirus phifelvirus picardvirus pikminvirus pleeduovirus pleetrevirus poushouvirus predatorvirus priunavirus psavirus psimunavirus pulverervirus questintvirus quhwahvirus radostvirus raleighvirus ravarandavirus ravinvirus rerduovirus rigallicvirus rimavirus rockefellervirus rockvillevirus rogerhendrixvirus ronaldovirus roufvirus rowavirus ruthyvirus samistivirus samunavirus samwavirus sandinevirus sanovirus sansavirus saphexavirus sashavirus sasvirus saundersvirus sawaravirus scapunavirus schnabeltiervirus schubertvirus seongbukvirus septimatrevirus seussvirus sextaecvirus skunavirus slashvirus sleepyheadvirus smoothievirus sonalivirus soupsvirus sourvirus sozzivirus sparkyvirus spbetavirus spizizenvirus squashvirus squirtyvirus stanholtvirus steinhofvirus sukhumvitvirus tandoganvirus tankvirus tantvirus terapinvirus teubervirus thetabobvirus tigunavirus timquatrovirus tinduovirus titanvirus tortellinivirus triavirus trigintaduovirus trinavirus trinevirus triplejayvirus unahavirus uwajimavirus vashvirus vedamuthuvirus vendettavirus vhulanivirus vidquintavirus vieuvirus vividuovirus vojvodinavirus waukeshavirus wbetavirus weaselvirus whackvirus whiteheadvirus wildcatvirus wilnyevirus wizardvirus woesvirus woodruffvirus xiamenvirus xipdecavirus yangvirus yonseivirus yuavirus yvonnevirus zetavirus please note that genus inceonvirus is likely misspelled incheonvirus.