Attenuated virus

An example of the use of an attenuated virus is the administration of the measles vaccine to an individual who has not had measles. The m easles (rubeola) vaccine contains the live, attenuated measles virus. The individual receiving the vaccine develops a mild or modified measles infection, which then produces immunity against the rubeola virus. The measles vaccine protects 95% of the recipients for several years or, for some individuals, for life. An example of a killed virus used for immunization is the cholera vaccine. This vaccine protects those who receive the vacdne for about 3 to 6 months. 

Polio is the only disease, at present, for which both hve and killed vaccines compete. Since the introduction of the killed vims (Salk) in 1956 and the live attenuated virus (Sabin) in 1962 there has been a remaikable decline in the incidence of poliomyelitis (Fig. 16.1). The inactivated polio vaccine (TPV) contains formalin-killed poliovirus of all three serotypes. On injection, the vaccine stimulates the production of antibodies of the IgM and IgG class which neutrahze the vims in the second stage of infection. A course of three injections at monthly intervals produces long-lasting immunity to all three poliovirus types. 

Vaccination to induce an adaptive immune response is expected for a broad range of infectious diseases and cancers. Traditional vaccines are mainly composed of live attenuated viruses, whole inactivated pathogens, or inactivated bacterial toxins. In general, these approaches have been successful for developing vaccines that can induce an immune response based on antigen-specific antibody and cytotoxic T lymphocyte (CTL) responses, which kill host cells infected with intracellular organisms (Fig. 1) [1,2], One of the most important current issues in vaccinology is the need for new adjuvants (immunostimulants) and delivery systems. Many of the vaccines currently in development are based on purified subunits, recombinant... 

Generation of antibodies that can recognize and bind to specific viruses is straightforward. A sample of live or attenuated virus, or a purified component of the viral caspid, can be injected into animals to stimulate polyclonal antibody production (or to facilitate monoclonal antibody production by hybridoma technology). Harvested antibodies are then employed to develop specific immunoassays that can be used to screen test samples routinely for the presence of that specific virus. Immunoassays capable of detecting a wide range of viruses are available commercially. The sensitivity, ease, speed and relative inexpensiveness of these assays render them particularly attractive. 

LAIV is made with live, attenuated viruses and is approved for intranasal administration in healthy people between 5 and 49 years of age (Table 41-2). Advantages of LAIV include its ease of administration, intranasal rather than intramuscular administration, and the potential induction of broad mucosal and systemic immune response. 

Yes. Vaccinia vaccine is recommended for laboratory workers who directly handle cultures, animals contaminated or infected with, nonhighly attenuated vaccinia virus, recombinant vaccinia viruses derived from nonhighly attenuated vaccinia strains, or other orthopoxviruses that infect humans. These would include monkeypox, cowpox, vaccinia, and variola. Other health-care workers, such as physicians and nurses whose contact with nonhighly attenuated vaccinia viruses is limited to contaminated materials such as medical dressings but who adhere to appropriate infection control measures, are at lower risk for accidental infection than laboratory workers. However, because a theoretical risk for infection exists, vaccination can be offered to this group. Vaccination is not recommended for people who do not directly handle nonhighly attenuated virus cultures or materials or who do not work with animals contaminated or infected with these viruses. 

There are two classical strategies for vaccination. One involves vaccination with either killed pathogenic organisms or subunits of the pathogenic organism. The other utilizes live attenuated viruses or bacteria that do not cause disease but have been derived from the pathogenic parent organism. 

A trivalent vaccine containing the live attenuated viruses for measles, mumps and rubella was first introduced in the United States in the early 1970s by Merck and Co Inc. Since that time, other triple vaccines have been developed using various different viral strains and many coim-tiies have licensed them either as the sole vaccine... 

Varicella Virus Vaccine (Varivax) [Vaccine] Uses Prevent varicella (chickenpox) Action Active immunization live attenuated virus Dose Adults Feds. 0.5 mL SQ, rqieat 4—8 wk Caution [C, M] Contra Immunocompromised ... 

Generation of antibodies that can recognize and bind to specific viruses is straightforward. A sample of live or attenuated virus, or a purified component of the viral caspid, can be injected... 

Live attenuated viruses, e.g. measles, mumps and yellow fever viral vaccines. 

Live attenuated virus vaccines for measles, mumps and rubella (MMR) have been combined into a single vaccine known as MMR vaccine. The MMR vaccine is effective as the single-virus vaccine composed of the respective strains and has been shown to be highly effective. The immunity induced by MMR is long lasting and may be lifelong. 

The controversy has reappeared with the introduction of a five component children s vaccine containing diphtheria, polio, measles, mumps, and rubella although this should be much more convenient and contains a killed polio instead of an attenuated virus which is known to occasionally revert to the active form, albeit in single numbers per million injections. In this case the children s vaccine should be safer and more convenient. 

The original polio vaccine was developed by Jonas Salk (for whom the Salk Institute in LaJolla is named). It is a "killed" virus. However, over the years it was found that this did not always impart a complete immunity. The Sabin vaccine contains an attenuated virus. It is interesting to note that the Sabin vaccine can cause an active infection in a rare number of cases. 

A range of different vaccine vectors has been developed over time to provoke an immune response within the body [127,142], However, it has only been comparatively recently that they have been applied to inducing mucosal immunity within the uterovaginal tract. The general vector platforms that have been used include attenuated viruses, live viruses, commensal bacteria, DNA vectors, and protein subunit/peptide or virus-like particles (Table 21.9). The choice of vector is dependent on a number of factors such as the pathogenic virus and bacterial type and the length of duration of immunity required. 

The purpose of this chapter is to review and discuss the preclinical safety evaluation strategy for vaccine approaches to the prophylaxis and treatment of viral diseases. This chapter will discuss the newer approaches to vaccination and will include recombinant proteins, peptides, polysaccharides, DNA plasmids, and viral vectors with and without adjuvants. It is outside the scope of this chapter to discuss whole cells expressing immunogens, live attenuated viruses, bacteria, or parasites. 

Rubella vaccine is a live attenuated virus vaccine. Most of the vaccines currently manufactured outside Japan are produced in human diploid cells and are based either on the RA 27/3 strain (the most widely used) or the Cendehill strain. In Japan, five different vaccine strains (for example TO 336 and MEQ 11) are produced in two different non-human substrates. In China, another vaccine strain (BRD-2) has been developed and produced in human diploid cells. Its antigenicity and reactogenicity are comparable to those of the RA 27/3 strain. 

Varicella vaccine (Varivax. Merck) is derived from live virus from u child with natural varicella. The virus has been attenuated by pos.sage through a series of guinea pig and human cell cultures. The final preparation is a lyophilized live, attenuated virus. The antigen form is whole virus. The antigen type is protein. The vaccine is well tolerated, with pain and redness at the injection site as the only. side effects. The vaccine has shown tremendous suece.ss in reducing infections. Indications arc... 

Alphavintses (group A tfhoviruses) Encephalitis, hemorrhagic fevers Attenuated virus tgcnerally elTeciivci None... 

F)jvi>irusesYellow fever, dengue. Attenuated virus (generally None... 

Mumps virus Mumps Attenuated virus None... 

LiHuenzu viru8 Influen/uiA. B,Cserotypes) Attenuated virus effective) Amantadine... 

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