page_title: Viral plaque
hierarchical_section_title: Viral plaque
caption_attribution_description: English: Plaques from a virus isolated from a compost heap near UCLA. The picture shows plaques created by a virus that infects bacteria. The bacteria infected in this instance is M. smegmatis.
context_page_description: A viral plaque is a visible structure formed within a cell culture, such as bacterial cultures within some nutrient medium. The bacteriophage viruses replicate and spread, thus generating regions of cell destructions known as plaques.
  Counting the number of plaques can be used as a method of virus quantification. These plaques can sometimes be detected visually using colony counters, in much the same way as bacterial colonies are counted; however, they are not always visible to the naked eye, and sometimes can only be seen through a microscope, or using techniques such as staining or immunofluorescence. Special computer systems have been designed with the ability to scan samples in batches.
  The appearance of the plaque depends on the host strain, virus and the conditions. Highly virulent or lytic strains give clear plaques, while strains that only kill a fraction of their hosts or only reduce the rate of cell growth give turbid plaques. Some partially lysogenic phages give bull's-eye plaques with spots or rings of growth in the middle of clear regions of complete lysis.
  Non-viral spontaneous hole formation in cell culture is called opiplasi.
context_section_description: A viral plaque is a visible structure formed within a cell culture, such as bacterial cultures within some nutrient medium (e.g. agar). The bacteriophage viruses replicate and spread, thus generating regions of cell destructions known as plaques.
  Counting the number of plaques can be used as a method of virus quantification. These plaques can sometimes be detected visually using colony counters, in much the same way as bacterial colonies are counted; however, they are not always visible to the naked eye, and  sometimes can only be seen through a microscope, or using techniques such as staining (e.g. neutral red for eukaryotes or giemsa for bacteria)  or immunofluorescence. Special computer systems have been designed with the ability to scan samples in batches.
  The appearance of the plaque depends on the host strain, virus and the conditions. Highly virulent or lytic strains give clear plaques, while strains that only kill a fraction of their hosts (due to partial resistance/lysogeny) or only reduce the rate of cell growth give turbid plaques. Some partially lysogenic phages give bull's-eye plaques with spots or rings of growth in the middle of clear regions of complete lysis.
  Non-viral spontaneous hole formation in cell culture (e.g. LLC-PK1, or the human gingival epithelial cell culture model, Gie-3B11) is called opiplasi (Greek; opi=hole; plasi=formation). These holes can grow to several millimeter in size. Spontaneous appearance of these holes can be induced and accelerated by proinflammatory cytokines such as Tumor Necrosis Factor-alpha  .
caption: Plaques from a virus isolated from a compost heap near UCLA. The bacterium is M. smegmatis.
exif: {"Image ImageDescription": "VLUU L200  / Samsung L200", "Image Make": "Samsung Techwin", "Image Model": "VLUU L200  / Samsung L200", "Image Orientation": "Horizontal (normal)", "Image XResolution": "96", "Image YResolution": "96", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "803111", "Image DateTime": "2009:01:20 12:23:16", "Image YCbCrPositioning": "Co-sited", "Image Copyright": "COPYRIGHT, 2007", "Image ExifOffset": "286", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail Orientation": "Horizontal (normal)", "Thumbnail XResolution": "1", "Thumbnail YResolution": "1", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "27038", "Thumbnail JPEGInterchangeFormatLength": "3705", "EXIF ExposureTime": "1/45", "EXIF FNumber": "14/5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2009:01:20 12:23:16", "EXIF DateTimeDigitized": "2009:01:20 12:23:16", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "1189469/884736", "EXIF ShutterSpeedValue": "563/100", "EXIF ApertureValue": "297/100", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "297/100", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "63/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3072", "EXIF ExifImageLength": "2304", "EXIF RelatedSoundFile": "RelatedSound", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "26902", "EXIF ExposureIndex": "1", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "35", "EXIF SceneCaptureType": "Standard", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}