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B Woodson

Publications and source records attributed to B Woodson.

9 recordsLinked to original sources
PubMed1999

Selective induction of protective MHC class I-restricted CTL in the intestinal lamina propria of rhesus monkeys by transient SIV infection of the colonic mucosa.

The identification of mucosal immune responses required for protection against sexual transmission of HIV is essential for the development of an efficacious vaccine. To gain a better understanding of these responses, we have characterized the immune responses in the lamina propria (LP) and epithelium of the jejunum, the mesenteric lymph nodes, and peripheral blood (PBMC) of 11 rhesus monkeys following colonic exposure to two molecular clones of SIV. Two monkeys had no signs of infection. Three monkeys became persistently infected. Transient infections, characterized by the sporadic detection of virus in the periphery and/or detection of SIV-specific immune responses in either the gut-associated tissues or PBMC, were induced in six of the monkeys. One persistently infected and three transiently infected monkeys had high levels of SIV env-specific MHC class I restricted CTL in the jejunal LP. Another transiently infected monkey had SIV-specific IgA secreting B cells in the LP. Three or six months postexposure, these animals and four naive controls were challenged intracolonically with the heterologous primary isolate, SIV/DeltaB670. All four monkeys with strong SIV env-specific MHC-restricted CTL in the LP were protected, whereas none of the naive controls or the remaining seven monkeys with little or no CTL in the LP were protected. These experiments provide the first direct evidence that transient mucosal infection can induce SIV-specific immunity that remains localized to the gut-associated tissues. Furthermore, a strong correlation between SIV env-specific MHC-restricted CTL in the LP and protection against colonic mucosal challenge was observed.

Animals↗
PubMed1998

Immunization with a recombinant envelope protein (rgp90) of EIAV produces a spectrum of vaccine efficacy ranging from lack of clinical disease to severe enhancement.

We have previously reported that immunization of ponies with a baculovirus-expressed recombinant surface unit envelope protein (rgp90) for equine infectious anemia virus (EIAV) resulted in enhancement of disease symptoms and virus replication in 4 of 4 vaccine recipients subjected to a heterologous virus challenge (rpg90 I vaccine trial) (Wang et al., 1994). To extend these studies of EIAV vaccine enhancement, two additional and independent rgp90 vaccine trials (rgp90 II and rgp90 III) were performed. Combined, a total of 13 ponies were immunized with the rgp90 immunogen using our standard vaccination procedures and challenged with a heterologous strain of EIAV. In contrast to the uniform enhancement observed in the rgp90 I vaccine trial, the severity of clinical symptoms varied markedly among the rgp90 recipients: 5 ponies experienced enhanced disease symptoms, 5 ponies experienced moderate disease symptoms, and 3 ponies remained asymptomatic. Of particular interest, in the 5 ponies with enhanced clinical symptoms was a severe thrombocytopenia (< or = 105,000 platelets/microliter) evident coincident with the first febrile episode following virus challenge. Thrombocytopenia was either absent (7/10 ponies) or substantially delayed (3/10 ponies) in naive control ponies inoculated with the standard EIAVPV challenge. Measurements of virus replication in the challenged vaccine recipients indicated a correlation between the level of viral RNA in plasma and the severity of the disease. Interestingly, an association was not observed between serum antibody reactivity to the vaccine or native viral antigens and the frequency of enhancement. Thus, these observations demonstrate a previously unrecognized complexity of rgp90 vaccine efficacy that has important implications for AIDS vaccine development.

Animals↗
PubMed1973

Inhibition of RNA-dependent DNA polymerase of Rous sarcoma virus by thiosemicarbazones and several cations.

The RNA-dependent DNA polymerase of Rous sarcoma virus is inhibited by N-methyl isatin beta-thiosemicarbazone and by thiosemicarbazide, but not by semicarbazide. These inhibitors also inactivate, upon contact with the virion, the transforming ability of Rous sarcoma virus. Sulfhydryl donors, such as 2-mercapto-ethanol, can prevent these effects. The RNA-directed activity of the purified polymerase is inhibited to a greater degree than is the DNA-directed activity. Two cations, Cu(++) and Hg(++), can inhibit RNA-dependent DNA polymerase and inactivate the transforming ability of the virus. Synergism between N-methyl isatin beta-thiosemicarbazone and Cu(++) occurs, since treatment of the virus with a low dose of either N-methyl isatin beta-thiosemicarbazone or Cu(++) has little effect; however, when the two compounds are mixed together, significant inactivation occurs. This observation supports the hypothesis that the antiviral action of thiosemicarbazones is a function of their ability to act as a ligand for metallic ions. Several cations (Ag(+), Co(++), Zn(++), Cd(++), and Ni(++)) significantly inactivate the RNA-dependent DNA polymerase, but have little effect on the transforming ability. In view of this result, the conclusion that the enzyme activity is required for transformation remains open to question.

Animals↗
PubMed1968

Induction of poxvirus ribonucleic acid polymerases.

Two distinct ribonucleic acid polymerase activities were induced in HeLa cells by poxvirus infection. These activities differ both in their properties and the time of their appearance after infection. One catalyzes the dAT (copolymer of deoxyadenylate and deoxythymidylate)-primed conversion of adenosine triphosphate and uridine triphosphate into an acid-insoluble product. This enzyme is detectable only if deoxyribonucleic acid synthesis has been blocked. In contrast, the accumulation of progeny genomes is a necessary condition for induction of the second enzyme. The latter activity, which is unmasked by detergent treatment, is found exclusively in maturing virus particles. The possibility that both enzymes are involved in transcribing the viral genome is discussed.

Cycloheximide↗