Immunization does not interfere with uptake and transport by motor neurons of the binding fragment of tetanus toxin.
The nontoxic binding domain of tetanus toxin (fragment C or TTC) readily undergoes retrograde axonal transport from an intramuscular injection site. This property has led to investigation of TTC as a possible vector for delivering therapeutic proteins to motor neurons. However, the vast majority of individuals in the developed world have been vaccinated with tetanus toxoid and have circulating antitetanus antibodies that cross-react with TTC and may block the delivery of a TTC-linked therapeutic protein. However, it is uncertain whether the immune response is capable of completely neutralizing an intramuscular depot of protein prior to its internalization by presynaptic nerve terminals, where it is inaccessible to antibody. We have evaluated uptake of rhodamine-labeled TTC following intramuscular injection in normal animals and animals vaccinated with tetanus toxoid prior to injection of fluorescently labeled TTC. All animals demonstrated uptake of TTC, with fluorescence appropriately localized to the hypoglossal nerve and nucleus. The distribution and intensity of fluorescence within neurons and processes were indistinguishable between the two groups and were characteristic of TTC. Vaccinated animals showed levels of uptake of TTC into the brain comparable to those of immunologically naïve animals as measured by quantitative fluorimetry. All vaccinated animals had protective levels of antitetanus antibodies as measured by ELISA. Uptake of TTC by nerve terminals from an intramuscular depot is an avid and rapid process and is not blocked by vaccination associated with protection from tetanus toxin.
Research Service, Veterans Affairs Health Care System, Baltimore, Maryland, USA. pfishman@umaryland.edu
Paul S
PS
Fishman
Christopher C
CC
Matthews
Deborah A
DA
Parks
Michael
M
Box
Neil F
NF
Fairweather
D000818:Animals; D000906:Antibodies / Q000097:blood / Q000276:immunology; D001370:Axonal Transport / Q000276:immunology*; D004337:Drug Carriers / Q000378:metabolism; D007002:Hypoglossal Nerve / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D007114:Immunization / Q000009:adverse effects*; D007273:Injections, Intramuscular; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D009046:Motor Neurons / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D010446:Peptide Fragments / Q000276:immunology* / Q000378:metabolism* / Q000493:pharmacokinetics; D017729:Presynaptic Terminals / Q000276:immunology / Q000378:metabolism*; D021381:Protein Transport / Q000276:immunology; D012235:Rhodamines; D013744:Tetanus Toxin / Q000276:immunology* / Q000378:metabolism* / Q000493:pharmacokinetics; D014059:Tongue / Q000294:innervation / Q000378:metabolism
D000906:Antibodies; D004337:Drug Carriers; D010446:Peptide Fragments; D012235:Rhodamines; D013744:Tetanus Toxin; C040635:tetanus toxin fragment C