ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Antibodies, Right-Side-Up?

Updated on January 5, 2013

It Matters!

This post takes a short break from my series on evolution and bioinformatics to report on an exciting finding in the world of bacteriology!

Nearly 700 million annual cases of throat and skin infections are caused by the human bacterial pathogen Streptococcus pyogenes. Many of these are mild and fairly uncomplicated, though there are cases, like the one I’m about to describe, where bacterium invades the blood streams and induces an inflammatory response, often resulting in the death of the patient.

Did you know that this infectious agent also resides in your saliva? It can be a peaceful resident there, causing no symptoms at all. What then, converts this nonviolent colony into an invasive and life-threatening infection?

Researchers at Lund University in Sweden have recently reported that samples from a patient with a serious S. pyogenes infection reveal differences in the orientation of the patient’s antibodies at the surface of the bacteria from different sites in the body.

Whether or not you’re familiar with all of the players in an infection, you’ve probably heard of the Y-shaped proteins called antibodies that are produced by cells of the immune system. They function as part of an alarm system, recognizing and attaching to invaders such as viruses and bacteria, and signaling other cells to destroy the target.

Antibodies are divided into classes, the most common of which is IgG. Each IgG antibody is composed of a fragment crystallizable (Fc) region, and the fragment antigen-binding (Fab) region (the two arms of the Y):

Now, the antibodies must bind in the fragment antigen-binding (Fab) region in order for the immune system to be able to eliminate pathogens. However, many bacteria, including S. pyogenes, have proteins on their surface that interfere with this mechanism, by binding antibodies in the fragment crystallizable (Fc) region.

“By turning the antibodies around so that they are Fc-bound instead the bacteria can avoid detection by immune cells and subsequent killing,” said Pontus Nordenfelt, first author on the paper in which these findings are published.

“For bacteria that are equipped with IgG Fc-binding proteins we show that the orientation of antibodies bound to bacterial surfaces strictly depend on the local concentration of antibodies; we demonstrate this in a human patient as well.”

The study found that in the throat of an infected patient, the IgG antibodies were mostly bound to the bacterial surface via Fc, while in the blood, IgG was mostly bound via Fab.

Further investigation showed that efficient bacterial Fc-binding occurs only in IgG poor environments, such as saliva, where the bacteria are consequently protected from detection by the immune system.

“When there are very high amounts of antibodies, such as in blood, there [are] likely enough antibodies with a higher affinity than the bacterial Fc-binding. This allows the antibodies to bind the correct way in blood,” said Nordenfelt.

Nordenfelt says that the information provided in this study lays out the basic framework for the biological role of these IgG-binding proteins.

“Since these proteins are present in several important bacterial pathogens we hope that this will help future research in bacterial pathogenesis.”

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)