ABSTRACT
Rabies is a neurological disease with 100% lethality. Some of the rare human patients who survived after multiple drug treatment had severe sequelae. The present study showed that after 48 h of RABV inoculation, mice injected intracerebrally with anti-RABV F (ab')2 plus Bioporter® showed 70% survival compared to the control group, suggesting that transfection of anti-RABV antibodies to the brain may prevent or delay the spread of RABV at an early stage of infection. This result may provide important protocol results in intracellular antibody delivery to prevent the fatal outcome of the disease.
Subject(s)
Antibodies, Viral/administration & dosage , Drug Delivery Systems/methods , Immunoglobulin Fab Fragments/administration & dosage , Rabies Vaccines/administration & dosage , Rabies virus/drug effects , Rabies/prevention & control , Vaccination/methods , Animals , Brain/drug effects , Brain/virology , Disease Models, Animal , Female , Fluorescein-5-isothiocyanate/chemistry , Fluorescent Dyes/chemistry , Humans , Injections, Intraventricular , Mice , Rabies/immunology , Rabies/mortality , Rabies/virology , Rabies virus/immunology , Rabies virus/pathogenicity , Survival Analysis , Transfection/methodsABSTRACT
In 2010, a novel spotted fever group rickettsiosis was reported in the Atlantic rainforest coast of Brazil. The etiological agent was identified as Rickettsia sp. strain Atlantic rainforest, and the tick Amblyomma ovale was incriminated as the presumed vector. The present study evaluated under laboratory conditions four colonies of A. ovale: two started from engorged females that were naturally infected by Rickettsia sp. strain Atlantic rainforest (designated as infected groups); the two others started from noninfected females (designated as control groups). All colonies were reared in parallel from F0 engorged female to F2 unfed nymphs. Tick-naïve vesper mice (Calomys callosus) or domestic rabbits were used for feeding of each tick stage. Rickettsia sp. strain Atlantic rainforest was preserved by transstadial maintenance and transovarial transmission in A. ovale ticks for at least 2 generations (from F0 females to F2 nymphs), because nearly 100% of the tested larvae, nymphs, and adults from the infected groups were shown by PCR to contain rickettsial DNA. All vesper mice and rabbits infested by larvae and nymphs, and 50% of the rabbits infested by adults from the infected groups seroconverted, indicating that these tick stages were vector competent for Rickettsia sp. strain Atlantic rainforest. Expressive differences in mortality rates and reproductive performance were observed between engorged females from the infected and control groups, as indicated by 75.0% and 97.1% oviposition success, respectively, and significantly lower egg mass weight, conversion efficiency index, and percentage of egg hatching for the infected groups. Our results indicate that A. ovale can act as a natural reservoir for Rickettsia sp. strain Atlantic rainforest. However, due to deleterious effect caused by this rickettsial agent on engorged females, amplifier vertebrate hosts might be necessary for persistent perpetuation of Rickettsia sp. strain Atlantic rainforest in A. ovale under natural conditions.
