Virus infectious dose

Bovine herpes virus type 1 (BHV1) glycoprotein D (gDc) Tobacco leaf Sustained and specific humoral and cellular immune response in mice and cows when delivered once parenterally. Cows challenged with infectious dose of BHV1 exhibited milder symptoms over a shorter duration. 87... 

The strength may be in the form of the quantity of virus estimated to infect half (50%) of the inoculated culture, tissue culture infectious doses (TCID5o). For example, rubella virus vaccine contains 1,000 TCID50, which means each dose contains one thousand times the amount of virus present in one tissue culture infectious dose. 

TCID50 of the US Reference Mumps virus and 2,000 TCID50 of the US Reference Rubella virus. The first dose (half mL SC) of this vaccine is recommended at the age of 12 to 15 months. What is the tissue culture infectious dose of measles virus in a 50-milliliter vial ... 

HIV is present in peripheral blood mononuclear cells, the major source of transmitted virus. Titers, however, are quite low, about 10,000 infectious doses per ml of blood, so that the blood is less infectious than in hepatitis B virus infections. The amount present tends to fall after seroconversion and rises again during development of AIDS-related complex and AIDS. Smaller amounts of virus are also present in semen and saliva, and probably even smaller amounts in colostrum, the human cervix, and tears. Infection is reported in CD4 positive submucosal cells in the rectum and large bowel and could be a route of entry in homosexuals. 

Enteric viruses only reproduce within the human host and all follow the fecal-oral route of transmission (Girard et al., 2006). The most significant characteristic of enteric viruses is the low infectious dose to cause illness (<20 virons) and the ease by which they can be transferred from person to person (Mattison et al., 2007). Enteric viruses are also very stable with resistances to environmental stresses comparable to those associated with bacterial endospores (Mattison et al., 2007). 

The technical objective would be to assure that a consumer would not be exposed to an infectious dose of a pathogen from the drinking water. Such a dose can range from a few or perhaps only one virulent organism (PFU) for polio virus or certain protozoa such as Giardia lamblia, to hundreds of Shigella or perhaps millions of opportunistic... 

HIV (>31ogio HIV-I reduction), but was less effective for HBV-like viruses (>llogio PRV reduction, 2.41ogio VSV reduction) and for HCV-like viruses (2.91ogio Sindbis reduction). Studies in animals and humans confirmed the model virus results. Chimpanzees inoculated with Hemofil T, that had been spiked with HBV (30,000 chimpanzee infectious doses) and freeze dried/dry heated, later developed hepatitis During clinical trials,... 

Infectious Doses for Some Virus Infections (25-50% of Human Volunteers)... 

Virulence may be defined as the ability of a virus to invade host tissues and cause disease. Table 2 shows the infectious doses of some viruses are very low (data taken from ref. 3). 

M-M-R-n powder for injection mixture of 3 viruses at least 1,000 measles TCID o [tissue culture infectious doses], at least 20,000 mumps TCID g and at least 1,000 rubella TCID50 per 0.5 mL dose)... 

The evaluation of the risks associated with cancer virus research is extremely difficult, since we lack much scientific data on such vital characteristics as agent host range, infec-tivity, host susceptibility, and infectious dose (see Section 11.2). Because the potential consequences of accidental inoculation of laboratory workers with oncogenic viruses are so serious, standards have been developed for work with these agents (476, 477). The technique of risk assessment, which classifies both agents and experimental procedures on the basis of their relative hazards, is very useful for assigning particular ents into hazard categories based upon available data. 

The characteristics of the agent comprise the third element in assessment of risk. Oncogenic agents are classified according to risk based upon criteria established from the evaluation of animal data. The assumption is made that the infectious dose for an animal is related to the hypothetical human infectious dose. For purposes of risk assessment the risk criteria for oncogenic viruses are divided into three categories high, moderate, and low. 

Table 11.10 Infection route and infectious dose for humans of some bacteria and viruses...

Adverse Effects Adverse effects are seen regularly in patients given mitoxantrone (see Table 26-3). Patients often experience bluish discoloration of the sclera and the urine for 24 hours after infusion.46 Transient leukopenia and neutropenia are common with a nadir 10 to 14 days after the infusion. Patients should avoid exposure to infectious individuals during this time.46 Patients taking mitoxantrone should not receive live virus vaccines other vaccines should be held for 4 to 6 weeks after a mitoxantrone dose.46 Amenorrhea, caused by a direct toxic effect on the ovary, may be permanent, an important consideration because the MS population includes women of childbearing potential.27... 

To determine if the high in vitro potents of the anti-HIV compound 30 translates into antiviral efficiency in vivo, Datema et al. investigated the inhibition of HIV-1 production and of depletion of human T cells in HIV-1-infected SCID-hu Thy/Liv mice [37]. Steady levels of 100 ng of 30 or higher per mL in plasma resulted in significant inhibition of HIV p24 protein formation. Daily injection of 30 caused a dose-dependent decrease in viral p24 production, and this inhibition could be potentiated by coadministration of AZT (or DDI). This study suggested that 30 alone or in combination with the licensed anti-HIV agents AZT and DDI may decrease the virus load in HIV-infected patients and, by extension, that the infectious cell entry step is a valid target for antiviral chemotherapy of HIV disease. 

In addition to the stock of smallpox vaccine in the US, an additional 50-100 million doses are estimated to exist worldwide. Many countries still hold smallpox vaccine (vaccinia) stocks. WHO recommends that countries that still have stocks of smallpox vaccine (vaccinia) maintain these stocks. This recommendation has been made for two reasons. Firstly, small amounts of vaccine are still needed to vaccinate laboratory personnel handling vaccinia virus and other members of this virus family. Some of these viruses are found in nature and cause illness among animals, and some are used in research to make new, safer vaccines against a variety of infectious diseases. Secondly, smallpox vaccine, vaccinia, will also be needed in case of a deliberate or accidental release of smallpox virus, variola. 

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