Biomedical Engineering Reference
In-Depth Information
7.4 EvaluationofNanoviricidesinaSCID-huThy/
LivModelofHIV-1Infection
Antiretroviral.agents.can,.indeed,.improve.clinical.outcomes.in.HIV-1.infection,.and.more-
over,. such. therapies. have. demonstrably. reduced. the. death. rate. of. AIDS. in. this. country.
and. other. parts. of. the. world.
13
. Once. it. was. conirmed. that. no. one. drug. could. achieve.
durable. viral. suppression. or. clinical. beneit,. clinical. researchers. have. quickly. adopted.
various. combinations. of. therapeutics. as. they. have. become. available,. comprised. of. pro-
tease.and.reverse.transcriptase.inhibitors.
28,29
.This.has.helped.facilitate.the.development.
of.what.is.called.highly.active.antiretroviral.therapy.(HAART).
13
.However,.challenges.for.
HIV.therapy.still.remain,.particularly.in.the.areas.of.long-term.complications.of.therapy,.
persistent.low-level.viremia,.and.viral.drug.resistance.and.genetic.diversity.
30-32
.Resistance.
to.HAART.eventually.leads.to.AIDS.
The. SCID-hu. mouse. model,. in. which. human. fetal. lymphoid. tissue. is. implanted.
into. severe. combined. immunodeicient. (SCID). mice,. has. been. used. to. study. both. nor-
mal. hematopoiesis. and. the. pathogenesis. of. HIV-1. in. human. lymphoid. tissue.
33,34
. The.
SCID-hu. Thy/Liv. model. is. generated. by. coimplantation. of. human. fetal. thymus. and.
liver.beneath.the.kidney.capsule..The.implanted.tissues.become.vascularized,.fuse,.and.
grow.to.become.a.Thy/Liv.“organ,”.resembling.a.histologically.normal.human.thymus..
The. model. has. been. validated. as. an. in. vivo. model. for. evaluation. of. anti-HIV-1. drug.
candidates.
35
For.evaluation.of.the.eficacy.of.nanoviricides,.C.B-17.SCID.mice.were.coimplanted.with.
fetal. human. thymus. and. liver. tissue. fragments. under. the. capsule. of. the. left. kidney. of.
anesthetized.mice..The.implants.were.inoculated.with.5,000.viral.particles.of.HIV-1,.Ba-L,.
stock. virus. (1,250. ×. TCID
50
). by. direct. injection. after. surgical. exposure. of. the. implanted.
kidney.. The. mice. were. randomly. sorted. into. groups.. Mice. treated. with. nanoviricides.
received.an.i.v..injection.of.100.μl.of.a.10.mg/ml.solution.(~50.mg/kg).at.24,.48,.and.72.hours.
after.virus.inoculation..A.control.treatment.group.received.100.μl.of.PBS.i.v..at.24,.48,.and.
72.hours..A.positive.control.group.received.the.HAART.cocktail.(AZT.+.3TC.+.Efavirenz.
at.40.+.20.+.40.mg/kg,.respectively),.administered.p.o..one.time.daily.for.the.duration.of.
the.study,.beginning.24.hours.after.virus.inoculation..The.total.drug.load.with.NNVC.4.
and. 5. administered. in. this. study. was. about. 150. mg/kg.. In. contrast,. the. total. drug. load.
administered.for.the.HAART.cocktail.was.4,200.mg/kg.(1,680.+.840.+.1,680.of.AZT.+.3TC +.
Efavirenz,.respectively).
Treatment. with. HAART. and. NNVC. 4. and. 5. resulted. in. a. signiicant. reduction. in.
viral.load.in.the.Thy/Liv.implant,.as.shown.by.quantitative.PCR.(qPCR).(Figure 7.6).and.
viral.particle.counts.by.electron.microscopy.(EM).(Table 7.3)..qPCR.analysis.showed.that.
HAART.and.NNVC.4.and.5.treatment.reduced.the.implant.viral.load.by.approximately.
0.5.log
10
,.compared.to.the.vehicle.control.group,.on.day.30..NNVC.4.treatment.produced.
a.viral.load.reduction.slightly.greater.than.that.of.HAART.treatment..Similarly,.a.reduc-
tion.in.viral.load.was.also.observed.by.EM.analysis.of.implant.lymphocytes..As.shown.
in. Table 7.3,. viral. particle. counts. were. reduced. approximately. 20-fold. by. NNVC. 4. and.
5. treatment. (EM).. In. contrast,. HAART. treatment. reduced. the. lymphocyte. viral. particle.
count.by.approximately.ivefold.
Similar.to.the.reduction.in.viral.load,.both.HAART.and.
NNVC.treatment.had.long-term.effects.on.thymocyte.depletion,.as.shown.by.the.propor-
tion.of.CD4
+
CD8
+
.thymocytes.(double.positive).in.the.ifth.week.postinfection.(Figure 7.6)..
