{"version":"1.0","provider_name":"TBE Book","provider_url":"https:\/\/tbenews.com\/tbe","author_name":"IT","author_url":"https:\/\/tbenews.com\/tbe\/author\/brianong\/","title":"Chapter 11: Diagnostic of TBEV-infections - TBE Book","type":"rich","width":600,"height":338,"html":"<blockquote class=\"wp-embedded-content\" data-secret=\"dckT6G7oqy\"><a href=\"https:\/\/tbenews.com\/tbe\/chapter-11-diagnostic-of-tbev-infections\/\">Chapter 11: Diagnostic of TBEV-infections<\/a><\/blockquote><iframe sandbox=\"allow-scripts\" security=\"restricted\" src=\"https:\/\/tbenews.com\/tbe\/chapter-11-diagnostic-of-tbev-infections\/embed\/#?secret=dckT6G7oqy\" width=\"600\" height=\"338\" title=\"&#8220;Chapter 11: Diagnostic of TBEV-infections&#8221; &#8212; TBE Book\" data-secret=\"dckT6G7oqy\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\" class=\"wp-embedded-content\"><\/iframe><script>\n\/*! This file is auto-generated *\/\n!function(d,l){\"use strict\";l.querySelector&&d.addEventListener&&\"undefined\"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!\/[^a-zA-Z0-9]\/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret=\"'+t.secret+'\"]'),o=l.querySelectorAll('blockquote[data-secret=\"'+t.secret+'\"]'),c=new RegExp(\"^https?:$\",\"i\"),i=0;i<o.length;i++)o[i].style.display=\"none\";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute(\"style\"),\"height\"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):\"link\"===t.message&&(r=new URL(s.getAttribute(\"src\")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener(\"message\",d.wp.receiveEmbedMessage,!1),l.addEventListener(\"DOMContentLoaded\",function(){for(var e,t,s=l.querySelectorAll(\"iframe.wp-embedded-content\"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute(\"data-secret\"))||(t=Math.random().toString(36).substring(2,12),e.src+=\"#?secret=\"+t,e.setAttribute(\"data-secret\",t)),e.contentWindow.postMessage({message:\"ready\",secret:t},\"*\")},!1)))}(window,document);\n\/\/# sourceURL=https:\/\/tbenews.com\/tbe\/wp-includes\/js\/wp-embed.min.js\n<\/script>\n","thumbnail_url":"https:\/\/tbenews.com\/tbe\/wp-content\/uploads\/2024\/06\/Chapter-11-DIAGNOSTIC-scaled.jpg","thumbnail_width":2560,"thumbnail_height":1709,"description":"Chapter 11:Diagnostic of TBEV-infections Gerhard Dobler Key points Clinical confirmation of suspected TBEV infection Tick-borne encephalitis (TBE) manifests as a non-specific disease with symptoms of a febrile, influenza-like illness and, in some cases, an inflammatory infection of the central nervous system (CNS) that follows a few days later. Due to the lack of specific symptoms, a definitive confirmation of the diagnosis requires taking the history of the patient with regard to a possible tick bite or ingestion of unpasteurized milk in a known or suspected endemic area, plus a positive result from a classical virological test that confirms TBEV-infection either directly by the detection of virus or indirectly via detection of specific anti-virus antibodies.1 Prior to the introduction of molecular detection technologies such as polymerase chain reaction (PCR), the only technique available to detect TBEV infection was virus isolation, but this is rarely used today. The most common method of detecting TBEV infection nowadays is via serological assays, which have been developed from complement fixation or hemagglutination inhibition tests, through to modern immunoglobulin (Ig)-specific tests such as ELISAs and immunofluorescence (IF) assays. Understanding of the pathogenesis and immunology of TBEV infection is essential for the selection and interpretation of appropriate diagnostic tests (Fig. 1). For example, the European subtype of TBEV often induces a biphasic clinical course, whereas a monophasic course may be more prominent in those infected with the Far Eastern subtype or Siberian subtype.2 Following a bite from an infected tick, the virus is assumed to replicate locally within antigen-presenting cells and then subsequently within nearby lymph nodes. After replicating within the lymph nodes, the virus then spreads to the internal organs via the lymph and blood (causing viremia) and begins to replicate within the reticuloendothelial system.3 It is during this phase of the disease that the infected individual will often show non-specific, influenza-like symptoms. These symptoms will then begin to improve for several days before a second phase appears in up to 30% of infected individuals, and which includes CNS involvement varying in severity from meningeal irritation to meningoencephalo-myelitis and even death. The choice of whether a specific patient should be tested using an assay that directly or indirectly detects TBEV infection therefore depends on the phase of the infection of a given patient. Direct detection of TBEV infection Virus isolation The isolation of TBEV was the first diagnostic technique established for the confirmation of clinically suspicious CNS infections such as TBE. In the past, virus isolation from blood and brain samples was performed in newborn mice, with many of the \u2018old\u2019 TBEV strains (e.g., Scharl, Absettarov, Sofjin, KEM II, Alsace, Schaffhausen, etc.) isolated by intracerebral inoculation of patient material or tick suspensions. Cell culture was subsequently introduced and there are now a number of immortalized cell lines that can be used to isolate TBEV from patient material. The most frequently used cell lines are currently PS cells (porcine fetal kidney cells), Vero cells (green monkey fetal kidney cells), BHK-21 (baby hamster kidney cells), and A549 cells (human lung adenocarcinoma cells), although other lineages such as human neuroblastoma cells may also be used. Figure 1: Natural course of TBE with clinical symptoms, virus replication, and evolution of specific anti-TBE antibodies Table 1: Detection of TBEV by RT-PCR in patient samples according to stage of infection4 Click the image above to enlarge Virus can be detected in an infected individual\u2019s blood during the first febrile phase of the disease and can be detected predominantly in brain tissue during the second phase involving neurologic symptoms.4 The cerebrospinal fluid (CSF) does not usually contain viable virus and should therefore only be used for virus isolation under special circumstances. No systematic studies on the discharge of viable TBEV in the urine of patients infected with TBEV are available to date, but discharging in an immuno-compromised patient was observed to last for at least 56 days5 and intermittent discharging in urine was observed for a period of more than 700 days in experimentally infected monkeys.6 Virus isolation is no longer routinely used for diagnosis of a TBE infection but is still needed to identify the subtype of TBEV present in brain tissue samples from fatal cases or in blood samples taken during the febrile phase of the disease. Virus isolation is also used to isolate TBEV strains from other biological material (e.g., ticks, rodents, etc.) for use in subsequent genetic and phenotypic characterization. PCR The current technology of choice for the detection of TBEV is PCR, and there are several formats available. The earliest PCR-based method for detecting TBEV infection was nested RT-PCR,7-9 but a number of real-time RT-PCR assays for the detection of viral ribonucleic acid (RNA) in various clinical and biological samples have also been described.10 PCR-based methods have no clear role in the diagnosis of TBEV infection during the phase involving CNS symptoms because viral RNA cannot usually be detected in blood or CSF samples during this phase of the disease.4,8 However, TBEV phase of TBE as well as in brain tissue (if available) during the phase involving CNS symptoms. The RT-PCR format is therefore a valuable diagnostic tool when there is a need to confirm an infection with TBEV as the cause of a febrile illness following a tick bite, or when confirmation of a TBEV infection is sought in fatal cases. A recent Swedish study reported that TBEV RNA could also be detected by RT-PCR in urine samples from patients for up to 19 days after the start of neurologic symptoms.11 Another application of RT-PCR in this setting is the diagnosis of potential TBEV infections in immunosuppressed patients unable to develop antibodies to the virus. In these cases, TBEV RNA may be detectable within blood and CSF samples over a longer period of time compared with immunocompetent patients. Detectable TBEV was reported to be shed over a period of at least 56 days in 1 immunocompromised patient.5 Indirect detection of TBEV infection Purified antigenic components of the TBEV particle are essential in order to be able"}