No assay is currently available that can measure HCV IgM antibodies, and thus one cannot distinguish recent from recent contamination

No assay is currently available that can measure HCV IgM antibodies, and thus one cannot distinguish recent from recent contamination. of viral contamination: virologic (detection of computer virus) and serologic (detection of antibody, antigen, or both). The virologic approach includes: (1) isolation of infectious computer virus in cell culture; (2) detection of viral antigen by immunologic methods such as fluorescent antibody (FA) screening or enzyme immunoassay (EIA); (3) identification of viral particles Amsacrine hydrochloride by electron microscopy (EM); and (4) detection of viral nucleic acid by direct hybridization or following an amplification step such as polymerase chain reaction (PCR). Cytologic examination of tissues and cells may identify viral effects prompting a need for further investigation. Occasionally, the cytologic changes can be sufficiently specific to suggest a particular viral agent (e.g., cytomegalovirus (CMV)).3 The serologic approach to the diagnosis of viral infections includes a demonstration of: (1) immunoglobulin (Ig) G antibodies indicating recent, current (e.g., human immunodeficiency computer virus (HIV)), or past contamination as well as immunity following recovery or vaccination; (2) a significant rise in virus-specific IgG antibody suggestive of acute or recent contamination; (3) virus-specific antigens (e.g., hepatitis B surface antigen (HBsAg)); or (4) virus-specific IgM antibody in late acute- or early recovery-phase sera. EIAs capable of measuring the avidity of IgG antibodies to specific viruses have also been developed. Following a viral contamination, as the Amsacrine hydrochloride immune response matures, low-avidity antibodies are replaced with high-avidity antibodies. These assays have been used to distinguish primary from secondary antibody responses to vaccination and to natural contamination.4, 5 Specimen Collection and Transport The timing of specimen collection for the detection of viruses is crucial. For the detection of most viruses, it is important to obtain specimens soon after the onset of clinical symptoms (preferably within the first 3 to 4 4 days) when viral shedding is at its maximum. Optimal specimens for the diagnosis of viral contamination vary depending on the site or sites of disease. In general, tissues, aspirates, and body fluids are superior to swabs for the detection of viruses. However, in many circumstances, swabs may be the only specimen available. Body sites or lesions that CNOT10 can easily be sampled with a swab include the pharynx or nasopharynx, conjunctiva, urethra, cervix, vagina, and vesicles or ulcers on the skin or mucous membranes. Many swab types are available for specimen collection, including those made with a plastic, wooden, or flexible wire shaft and a tip made of cotton, Dacron, calcium alginate, or polyurethane.6 However, different swab types may not be suitable for detection of some viruses. Swabs with a wooden shaft may contain toxic products that inactivate herpes simplex virus. Cotton-tipped swabs may contain fatty acids that can interfere with the survival of species, but are suitable for the collection of specimens from the vagina, cervix, or urethra for the detection of and should be placed into VTM. A number of commercially prepared VTMs are available. 7 Tissues for virus detection may also be placed in VTM. VTM prevents drying, maintains viral viability during transport, and prevents the overgrowth of contaminating organisms.6 Swabs collected for bacterial isolation that are placed in Amies or other bacterial transport medium are unacceptable for detection of virus.6 The converse Amsacrine hydrochloride is also true; VTM contain antimicrobial brokers that inhibit most bacteria and fungi. Specimens such as blood, bone marrow, cerebrospinal fluid (CSF), urine, and other body fluids should be placed in clean sterile containers without VTM. Most respiratory viruses replicate preferentially in columnar epithelial cells located primarily in the posterior of the nasopharynx and the lower respiratory tract. For detection of most respiratory viruses, nasopharyngeal (NP) aspirates or washes, sputa, and bronchoalveolar lavage (BAL) specimens provide a better yield for detection of viruses than NP, nasal, or throat swabs.7 Oropharyngeal and lower respiratory tract specimens may be superior to NP specimens for the detection of avian influenza A/H5N1 infections in humans. Multiple samples may need to be collected to maximize yield. For detection of viruses in the gastrointestinal tract, freshly exceeded stool is usually superior to a rectal swab.6 Blood is an important specimen for isolation of certain viruses because viremia is a useful indicator of disease. Within blood, different viruses may be found.