20 research outputs found
Induction of humoral immune response to multiple recombinant Rhipicephalus appendiculatus antigens and their effect on tick feeding success and pathogen transmission
BACKGROUND: Rhipicephalus appendiculatus is the primary vector of Theileria parva, the etiological agent of East Coast fever (ECF), a devastating disease of cattle in sub-Saharan Africa. We hypothesized that a vaccine targeting tick proteins that are involved in attachment and feeding might affect feeding success and possibly reduce tick-borne transmission of T. parva. Here we report the evaluation of a multivalent vaccine cocktail of tick antigens for their ability to reduce R. appendiculatus feeding success and possibly reduce tick-transmission of T. parva in a natural host-tick-parasite challenge model.
METHODS: Cattle were inoculated with a multivalent antigen cocktail containing recombinant tick protective antigen subolesin as well as two additional R. appendiculatus saliva antigens: the cement protein TRP64, and three different histamine binding proteins. The cocktail also contained the T. parva sporozoite antigen p67C. The effect of vaccination on the feeding success of nymphal and adult R. appendiculatus ticks was evaluated together with the effect on transmission of T. parva using a tick challenge model.
RESULTS: To our knowledge, this is the first evaluation of the anti-tick effects of these antigens in the natural host-tick-parasite combination. In spite of evidence of strong immune responses to all of the antigens in the cocktail, vaccination with this combination of tick and parasite antigens did not appear to effect tick feeding success or reduce transmission of T. parva.
CONCLUSION: The results of this study highlight the importance of early evaluation of anti-tick vaccine candidates in biologically relevant challenge systems using the natural tick-host-parasite combination
Calculation of the efficacy of vaccines against tick infestations on cattle
Articles in International JournalsCattle ticks are responsible for great economic losses in cattle farming worldwide, and their main control method,
chemicals, has been showing problems, whether resulting from the development of resistant strains of ticks or
environmental contamination. Research studies directed toward developing vaccines against ticks are emerging. One
way to evaluate those vaccines is to calculate the percentage of efficacy. The aim of this study was to analyze scientific
publications archived in PubMed that used this method of assessment and discuss the main factors that may affect its
calculation. Thus, 25 articles addressing this subject were selected. The percentage of efficacy was usually calculated
in one of two ways, with one considering the reduced fertility of eggs and the other not. The latter method may
underestimate the vaccine efficacy, and the most complete formula for calculating the efficacy reflects how much the
vaccine actually affects the infestation. In our view, the use of the complete formula for calculating the percentage of
efficacy is broader and more representative of the vaccine effect on the tick population.RESUMO - Carrapatos de bovinos sĂŁo responsĂĄveis por grandes perdas econĂŽmicas para a pecuĂĄria bovina mundial e seu principal
mĂ©todo de controle, o quĂmico, vem apresentando problemas, seja pelo desenvolvimento de amostras de carrapatos
resistentes ou pela contaminação ambiental. Na tentativa de diminuir a utilização dos acaricidas, surgem pesquisas
direcionadas ao desenvolvimento de vacinas contra carrapatos. Uma maneira de avaliar essas vacinas Ă© pelo cĂĄlculo de
percentagem de eficĂĄcia. O objetivo deste trabalho foi analisar as publicaçÔes cientĂficas indexadas no PubMed que
utilizaram este método de avaliação e discutir os principais fatores que podem interferir no seu cålculo. Dessa maneira,
selecionaram-se 25 artigos que tratavam desse assunto. A percentagem de eficĂĄcia apareceu sendo calculada de duas
formas, uma considerando a redução da fertilidade dos ovos e a outra nĂŁo. Essa Ășltima pode subestimar a eficiĂȘncia da
vacina, e a fórmula de cålculo da eficåcia mais completa representa o quanto da infestação a vacina realmente reduziu.
Em nosso entendimento, a utilização da fórmula completa para o cålculo da percentagem de eficåcia é mais abrangente
e representativa do efeito da vacina na população de carrapatos
Development and validation of a microbiological assay for determination of chlorhexidine digluconate in aqueous solution
Induction of humoral immune response to multiple recombinant Rhipicephalus appendiculatus antigens and their effect on tick feeding success and pathogen transmission
Predictors of the Availability and Variety of Social Care Services for Older Adults: Comparison of Central European Countries
Nuclease Tudor-SN Is Involved in Tick dsRNA-Mediated RNA Interference and Feeding but Not in Defense against Flaviviral or Anaplasma phagocytophilum Rickettsial Infection.
Tudor staphylococcal nuclease (Tudor-SN) and Argonaute (Ago) are conserved components of the basic RNA interference (RNAi) machinery with a variety of functions including immune response and gene regulation. The RNAi machinery has been characterized in tick vectors of human and animal diseases but information is not available on the role of Tudor-SN in tick RNAi and other cellular processes. Our hypothesis is that tick Tudor-SN is part of the RNAi machinery and may be involved in innate immune response and other cellular processes. To address this hypothesis, Ixodes scapularis and I. ricinus ticks and/or cell lines were used to annotate and characterize the role of Tudor-SN in dsRNA-mediated RNAi, immune response to infection with the rickettsia Anaplasma phagocytophilum and the flaviviruses TBEV or LGTV and tick feeding. The results showed that Tudor-SN is conserved in ticks and involved in dsRNA-mediated RNAi and tick feeding but not in defense against infection with the examined viral and rickettsial pathogens. The effect of Tudor-SN gene knockdown on tick feeding could be due to down-regulation of genes that are required for protein processing and blood digestion through a mechanism that may involve selective degradation of dsRNAs enriched in G:U pairs that form as a result of adenosine-to-inosine RNA editing. These results demonstrated that Tudor-SN plays a role in tick RNAi pathway and feeding but no strong evidence for a role in innate immune responses to pathogen infection was found