Reactivation of retroviruses following vaccination

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Transient increases in numbers of infectious cells in an HIV-infected

chimpanzee following immune stimulation.

… it seems reasonable to assume, as has been hypothesized, that any

stimulus to the immune system, whether by intercurrent infection,

exposure to new or recall antigens, or injury with inflammation, could

enhance HIV expression in infected individuals.To test this hypothesis,

we subjected an HIV-1-infected chimpanzee to repeated specific and

nonspecific immune stimulation by inoculation of various vaccine

preparation. Transient increases both in numbers of infectious

peripheral blood cells and in some HIV-specific immune responses

occurred within 1 to 2 weeks after most inoculations, including

administration of the immune globulin. These results have important

implications for the use of immunotherapy as a treatment for

HIV-infected persons and for immunization of HIV-infected infants and

children against other pathogens. They suggest that both immunotherapy

and vaccination of HIV-infected individuals should be accompanied by

administration of an antiviral drug(s). PMID: 1540418

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Effect of immunization with a common recall antigen on viral expression

in patients infected with human immunodeficiency virus type 1

Activation of the immune system is a normal response to antigenic

stimulation, and such activation enhances the replication of human

immunodeficiency virus type 1 (HIV-1). We studied the effect of

immunization with a common recall antigen on viral expression in

HIV-1-infected patients, on the ability to isolate virus, and on the

susceptibility to HIV-1 infection of peripheral-blood mononuclear cells

(PBMCs) from control subjects not infected with HIV-1 …Activation of

the immune system by an ongoing antigen-specific immune response to an

exogenous stimulus transiently increases the expression of HIV-1 and may

enhance the susceptibility of uninfected subjects to HIV-1

PMID: 8606717

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Antigenic stimulation by BCG vaccine as an in vivo driving force for SIV

replication and dissemination.

The impact of antigenic stimulation on the dynamics of simian

immunodeficiency virus (SIV) replication was studied following repeated

intravenous BCC inoculation of a SIV infected macaque. At the site of a

delayed type hypersensitivity reaction to purified protein derivative of

M. tuberculosis, a distinctive SIV variant was noted, probably as a

result of the infiltration of activated antigen-specific T cell clones

as opposed to infection by blood borne virus in situ. The dynamics of

SIV quasispecies in peripheral blood suggests sequential waves of viral

replication, illustrating the role of antigenic stimulation as a driving

force in viral dissemination and pathogenesis

PMID: 9546787

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Activation by malaria antigens renders mononuclear cells susceptible to

HIV infection and re-activates replication of endogenous HIV in cells

from HIV-infected adults

We have tested the hypothesis that activation of T cells by exposure to

malaria antigens facilitates both de novo HIV infection and viral

reactivation and replication. PBMC from malaria-naive HIV-uninfected

European donors could be productively infected with HIV following in

vitro stimulation with a lysate of Plasmodium falciparum schizonts and

PBMC from malaria-naive and malaria-exposed (semi-immune) HIV-positive

adults were induced to produce higher levels of virus after stimulation

with the same malaria extract. PMID: 15491470

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Activation of virus replication after vaccination of HIV-1-infected

individuals

…The potential adverse consequences of vaccine-induced activation of

HIV-1 replication deserve consideration in formulating guidelines for

immunization… PMC2192265

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Human immunodeficiency virus-type 1 replication can be increased in

peripheral blood of seropositive patients after influenza vaccination

PMID: 7620162

full text:

http://bloodjournal.hematologylibrary.org/cgi/reprint/86/3/1082

<http://bloodjournal.hematologylibrary.org/cgi/reprint/86/3/1082>

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an investigation of whether or not nef-deleted SIV could be reactivated

in vivo by immune activation of the host was conducted …. two

control monkeys that had suppressed replication of pathogenic SIV were

examined. During the infection virus became undetectable or persisted at

a low level of replication... At this time-point … monkeys were

immune-activated by a vaccinia virus (VV) super-infection…. the two

non-progressing monkeys infected with pathogenic SIV showed a noticeable

but transient enhancement of SIV replication and increased SIV antibody

titers. PMID: 9349473

full text http://vir.sgmjournals.org/cgi/reprint/78/10/2523

<http://vir.sgmjournals.org/cgi/reprint/78/10/2523>

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We analyzed cocultures of HIV-pulsed dendritic cells that had matured in

the presence of tetanus toxoid and CD4+ T cells before and after

inducing an antigen-specific response by in vivo immunization with

tetanus toxoid. During antigen-specific immune activation, 100 times

less HIV was needed to initiate a productive infection. These findings

provide a model system to further delineate the relationship between

immune activation and the propagation of HIV infection and suggest a

mechanism for the epidemiol. observations of an increased ease of

developing HIV infection and faster progression for HIV disease in geog.

area where immune activation is prevalent. 8627183

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Induced prion protein controls immune-activated retroviruses in the

mouse spleen

..... In summary, our experiments have revealed, by correlation, a

crucial role of PrP expression in the limitation of a common, but

previously unrecognized, phenomenon in the mouse spleen, namely the

massive activity of endogenous retroviruses in germinal centers after

various immune-stimulations. PMID: 17987132