''SMHBZ8'' is a lytic

bacteriophage A bacteriophage (), also known informally as a phage (), is a virus that infects and replicates within bacteria. The term is derived . Bacteriophages are composed of proteins that Capsid, encapsulate a DNA or RNA genome, and may have structu ...

that infects the bacteria ''

Streptococcus mutans ''Streptococcus mutans'' is a Facultative anaerobic organism, facultatively anaerobic, gram-positive coccus (round bacteria, bacterium) commonly found in the human oral cavity and is a significant contributor to dental caries, tooth decay. The m ...

''. The virus was isolated in 2020.

Genome and morphology

Transmission electron microscopy Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a g ...

(TEM) found ''SMHBZ8'' to have a B1 morphology with an isometric head diameter of approximately 56 nm, a long non-contractile tail with an approximate length of 244 nm, and a tail width of 10.9 nm. Whole genome sequencing revealed a genome size of 32,460

base pairs A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

. Analysis indicated that ''SMHBZ8'' appeared to be related to other ''S. mutans'' phages, including ''M102'', ''M102AD'', and ''APCM01''. While all four phages shared approximately 75% sequence identity, core gene analysis identified only seven genes fully conserved across all genomes. ''SMHBZ8'' possessed 32 unique genes compared to the other phages, with two unique genes coding for

lysin Lysins, also known as endolysins or murein hydrolases, are hydrolase, hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able ...

s (QKE60409.1 and QKE60410.1) being identified.

Research

''SMHBZ8'' has been studied as a possible

phage therapy Phage therapy, viral phage therapy, or phagotherapy is the therapeutic use of bacteriophages for the treatment of pathogenic bacterial infections. This therapeutic approach emerged at the beginning of the 20th century but was progressively r ...

agent to treat

tooth decay Tooth decay, also known as caries,The word 'caries' is a mass noun, and is not a plural of 'carie'.'' is the breakdown of teeth due to acids produced by bacteria. The resulting cavities may be a number of different colors, from yellow to black ...

by infecting and causing lysis in ''Streptococcus mutans'', a key bacteria that produces acid leading to decay. Preclinical studies showed that ''SMHBZ8'' was able to reduce existing biofilms in

dentin Dentin ( ) (American English) or dentine ( or ) (British English) () is a calcified tissue (biology), tissue of the body and, along with tooth enamel, enamel, cementum, and pulp (tooth), pulp, is one of the four major components of teeth. It i ...

samples.

References

{{taxonbar, from1=Q125989807 Caudovirales