Attenuated
OPV is an attenuated vaccine, produced by the passage of the virus through nonhuman cells at a subphysiological temperature, which produces spontaneous mutations in the viral genome. Oral polio vaccines were developed by several groups, one of which was led by Albert Sabin. Other groups, led by Hilary Koprowski and H.R. Cox, developed their own attenuated vaccine strains. In 1958, the National Institutes of Health created a special committee on live polio vaccines. The various vaccines were carefully evaluated for their ability to induce immunity to polio, while retaining a low incidence of neuropathogenicity in monkeys. Large-scale clinical trials performed in the Soviet Union in late 1950s to early 1960s by Mikhail Chumakov and his colleagues demonstrated safety and high efficacy of the vaccine. Based on these results, the Sabin strains were chosen for worldwide distribution. Fifty-seven nucleotide substitutions distinguish the attenuated Sabin 1 strain from its virulent parent (the Mahoney serotype), two nucleotide substitutions attenuate the Sabin 2 strain, and 10 substitutions are involved in attenuating the Sabin 3 strain. The primary attenuating factor common to all three Sabin vaccines is a mutation located in the viruss internal ribosome entry site, which alters stem-loop structures and reduces the ability of poliovirus to translate its RNA template within the host cell. The attenuated poliovirus in the Sabin vaccine replicates very efficiently in the gut, the primary site of infection and replication, but is unable to replicate efficiently within nervous system tissue.
Pigmented purpuric dermatosis refers to one of the three major classes of skin conditions characterized by purpuric skin eruptions. Pigmented purpuric dermatosis are distinguished from other purpura by size (0.3–1 cm) and are most often seen in the lower extremities. : 829   Pigmentary purpuric eruptions may present with one of several clinical patterns. There may be overlapping characteristics among pigmented purpuric dermatosis and between their signs and those of other purpuric eruptions. : 829   Examples of the pigmented purpuric dermatosis group include:: 829–30 
Schambergs disease
Majocchis disease (Purpura annularis telangiectodes)
Gougerot-Blum syndrome (Pigmented purpuric lichenoid dermatitis)
Ducas and Kapetanakis pigmented purpura
Lichen aureusAlthough vascular damage may be present, it is insufficient for these conditions to be considered forms of vasculitis.A few very small non-blinded studies of treatment with narrow-band ultraviolet light have been reported as promising. See also
Purpura
Skin lesion
List of cutaneous conditions

References


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