Viral contaminants

The early immunoglobulin products prepared by cold-ethanol fractionation were found to be free from transmitting hepatitis infection (106,108) this was not the case with products prepared by alternative methods (109). Subsequentiy, some batches of intravenous immunoglobulin transmitted hepatitis infection (110), emphasizing the importance of estabHshing vaHdated procedures for dealing with potential viral contaminants (111). 

Vimses are obligate intracellular parasites. They only exhibit activity by infecting other living organisms, thus they are not a practical concern in industrial microbiological fields. The exception is where viral contamination of the product or process represents a threat of transmission of disease. Microscopic insects and protozoans are also not addressed in this article (see Insectcontroltechnology). 

Semm is expensive, the 1992 price was 400/L, and supply depends on cattie supply. Use of this semm also poses significant difficulties in vahdating processes for absence of viral contamination. Hence, a goal in cell culture technology is to develop semm-free media for cell culture. Much work has gone into developing semm-free media and a sizable portion of cell culture research is devoted to this project. A detailed discussion of semm-free media development is available (5). 

Evans, M. R., Meldrum, R., Lane, W., Gardner, D., Ribeiro, C. D., Gallimore, C. L, and Westmoreland, D. (2002). An outbreak of viral gastroenteritis following environmental contamination at a concert hall. Epidemiol. Infect. 129, 355-360. 

There are many possible causes of acute diarrhea, but infection is the most common cause. Infectious diarrhea occurs because of food and water contamination via the fecal-oral route. Viruses are the cause in a large proportion of cases. Likely viral suspects include Rotavirus, Norwalk, and adenovirus. Patients usually exhibit sudden low-grade fever, vomiting, and watery stools. 

Hepatitis E is a non-enveloped single-stranded messenger RNA virus of unclassified genus.18 The HEV is similar to HAV in that the virus is harvested in contaminated feces, thus infecting people via the fecal-oral route. High HEV levels in the bile often prompt viral shedding in the feces. The severity of hepatic damage is dependent on the HEV strain Mex 14, Sar 55, or the US 2 strain.19 No cases of chronic hepatitis E have yet been documented. 

Nonpharmacologic measures are critical to prevent the spread of viral conjunctivitis. Patients should not share towels or other contaminated objects, should avoid close contact with other people and avoid swimming for 2 weeks.10 The virus remains viable on dry surfaces for more than 2 weeks.13 Take care in the medical setting to thoroughly decontaminate instruments and wash hands.11... 

In the region with pesticide contamination where subjects contracted viral hepatitis A, the pre-jaundice period was 4.2 days (in the control area, 5.1), the jaundice period lasted 32 days (22.4 in the control area), the liver enlarged more than in the control area and took longer to return to normal size, there was a larger number of patients who also had an enlarged spleen, there was more frequent damage to the nervous and cardiovascular systems (1.5-2 times higher than in the control area), mixed syndrome was observed more often (45% of the time, compared to 12.6% in the control area), and the illness was more frequently serious. 

The risk of viral contamination in plant-based medicinal products, and requirements for strategies to ensure that the product is consistently free of contaminating viruses, is discussed in detail in the EMEA document, while it is not addressed by the FDA. In addition to contamination by insect, bird and animal excreta or carcases, organic fertilizer, production personnel and equipment, the EMEA document lists plant virus infection as a source of contamination and claims that "... freedom from contamination with all types of viruses, irrespective of natural tropism, should be demonstrated. ... 

In addition to the urgent problem of capacity, manufacturers have to cope with the operating costs of production, which are increased by the need for skilled personnel and expensive media components. Another cost driver is the inherent contamination risk when using mammalian cell culture systems. All materials must be checked closely for bacterial and viral contamination, and the presence of prions and endotoxins. This affects not only the manufacturing process, but also downstream materials and even human semm albumin (HSA) used for formulations. In the end, production costs add up to 100-1000 per gram of therapeutic protein. 

It is a hantavirus that produces a viral hemorrhagic fever. It is normally found in Central and Eastern Asia. The natural reservoir is the striped field mouse (Apodemus agrarius) and the virus is shed in their urine. Infection occurs after inhalation of dust contaminated with excreta from infected mice or from aerosol of animal blood or fluids. Does not produce disease in animals. This is a biosafety level 3 agent. 

Biopharmaceutical products are also subjected to screening for the presence of viral particles prior to final product release. Although viruses could be introduced, for example, via infected personnel during downstream processing, proper implementation of GMP minimizes such risk. Any viral particles found in the finished product are most likely derived from raw material sources. Examples could include HIV or hepatitis viruses present in blood used in the manufacture of blood products. Such raw materials must be screened before processing for the presence of likely viral contaminants. 

An alternative assay format entails the use of virus-specific DNA probes. These can be used to screen the biopharmaceutical product for the presence of viral DNA. The assay strategy is similar to the dot blot assays used to detect host-cell-derived DNA contaminants, as discussed earlier. 

The starting material will likely be contaminated by intact, viable hepatitis B viral particles (and perhaps additional viruses, such as HIV). This necessitates introduction of stringent purification procedures to ensure complete removal of any intact viral particles from the product stream. A final product QC test to confirm this entails a 6-month safety test on chimpanzees. 

Product manufacture entails viral vector propagation in a suitable animal packing cell line (known as HEK 293). After cell recovery and lysis, the crude product is clarified by filtration and concentrated by ultrafiltration. The product is then treated with a nuclease preparation in order to degrade contaminant DNA and further downstream processing entails multi-step high-resolution column chromatography (see also Figure 14.7). 

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