Vaccine Efficacy of Bm86 Ortholog of H. a. anatolicum, rHaa86 Expressed in Prokaryotic Expression System

The use of tick vaccine in controlling ticks and tick borne diseases has been proved effective in integrated tick management format. For the control of H. a. anatolicum, Bm86 ortholog of H. a. anatolicum was cloned and expressed as fusion protein in E. coli as E. coli-pETHaa86. The molecular weight of the rHaa86 was 97 kDa with a 19 kDa fusion tag of thioredoxin protein. The expressed protein was characterized immunologically and vaccine efficacy was evaluated. After 120 hours of challenge, only 26% tick could successfully fed on immunized animals. Besides significant reduction in feeding percentages, a significant reduction of 49.6 mg; P < .01 in the weight of fed females in comparison to the females fed on control animals was recorded. Following oviposition, a significant reduction of 68.1 mg; P < .05 in the egg masses of ticks fed on immunized animals in comparison to the ticks fed on control animals was noted. The reduction of number of females, mean weight of eggs, adult females and efficacy of immunogen were 73.8%, 31.3%, 15.8%, and 82.3%, respectively. The results indicated the possibility of development of rHaa86 based vaccine as a component of integrated control of tick species

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 são responsáveis por grandes perdas econômicas para a pecuária bovina mundial e seu principal método de controle, o químico, 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 é pelo cálculo de percentagem de eficácia. O objetivo deste trabalho foi analisar as publicações científicas indexadas no PubMed que utilizaram este método de avaliação e discutir os principais fatores que podem interferir no seu cálculo. Dessa maneira, selecionaram-se 25 artigos que tratavam desse assunto. A percentagem de eficácia apareceu sendo calculada de duas formas, uma considerando a redução da fertilidade dos ovos e a outra não. Essa última pode subestimar a eficiência da vacina, e a fórmula de cálculo da eficácia mais completa representa o quanto da infestação a vacina realmente reduziu. Em nosso entendimento, a utilização da fórmula completa para o cálculo da percentagem de eficácia é mais abrangente e representativa do efeito da vacina na população de carrapatos

Vaccination against Bm86 Homologues in Rabbits Does Not Impair Ixodes ricinus Feeding or Oviposition

Human tick-borne diseases that are transmitted by Ixodes ricinus, such as Lyme borreliosis and tick borne encephalitis, are on the rise in Europe. Diminishing I. ricinus populations in nature can reduce tick exposure to humans, and one way to do so is by developing an anti-vector vaccine against tick antigens. Currently, there is only one anti-vector vaccine available against ticks, which is a veterinary vaccine based on the tick antigen Bm86 in the gut of Rhipicephalus microplus. Bm86 vaccine formulations cause a reduction in the number of Rhipicephalus microplus ticks that successfully feed, i.e. lower engorgement weights and a decrease in the number of oviposited eggs. Furthermore, Bm86 vaccines reduce transmission of bovine Babesia spp. Previously two conserved Bm86 homologues in I. ricinus ticks, designated as Ir86-1 and Ir86-2, were described. Here we investigated the effect of a vaccine against recombinant Ir86-1, Ir86-2 or a combination of both on Ixodes ricinus feeding. Recombinant Ixodes ricinus Bm86 homologues were expressed in a Drosophila expression system and rabbits were immunized with rIr86-1, rIr86-2, a combination of both or ovalbumin as a control. Each animal was infested with 50 female adults and 50 male adults Ixodes ricinus and tick mortality, engorgement weights and egg mass were analyzed. Although serum IgG titers against rIr86 proteins were elicited, no effect was found on tick feeding between the rIr86 vaccinated animals and ovalbumin vaccinated animals. We conclude that vaccination against Bm86 homologues in Ixodes ricinus is not an effective approach to control Ixodes ricinus populations, despite the clear effects of Bm86 vaccination against Rhipicephalus microplus

Perception of Ticks and Tick-Borne Diseases Worldwide

In this comprehensive review study, we addressed the challenge posed by ticks and tick-borne diseases (TBDs) with growing incidence affecting human and animal health worldwide. Data and perspectives were collected from different countries and regions worldwide, including America, Europe, Africa, Asia, and Oceania. The results updated the current situation with ticks and TBD and how it is perceived by society with information bias and gaps. The study reinforces the importance of multidisciplinary and international collaborations to advance in the surveillance, communication and proposed future directions to address these challenges

Genetic transformation of arthropod vectors for control of vector borne diseases

305-314The vector borne diseases cause heavy loss to mankind and livestock industry throughout the world. Global climate changes reported to contribute to the recurrence and new epidemics of vector borne diseases. Unfortunately, the available strategies to control vector borne diseases are insufficient and public health burden of the major vector borne diseases is on increasing trend. Complete eradication of a vector population is not realistic and desirable for many arthropod vector species due to biological constraints. Genetic transformation of vectors offers the way to control the diseases transmitted by the arthropod vectors without killing them and is also an economically viable option. Genetic transformation of arthropod vectors is a new strategy in the genomic era in which the synthetic effector gene is introduced into the genome of vectors to block the developmental stages of parasite/pathogen inside the vector and subsequent driving of the effector gene into the wild vector population in a geographical area. However, the knowledge on the putative risk factors associated with the release of transgenic arthropod vectors in the field is lacking and considerable work is needed before the deployment of transgenic arthropod vectors in nature

Control of ticks of ruminants, with special emphasis on livestock farming systems in India: Present and future possibilities for integrated control - A review

India is predominantly an agricultural country with about 70% of her population dependent on income from agriculture. Although India accounts for a significant share of world’s livestock resources, livestock production is greatly affected by ticks and tick-borne diseases (TTBDs). Therefore, India represents a particularly interesting scenario for the study of TTBDs. Herein, we review the problems and opportunities for the integrated control of ticks of ruminants with special emphasis on livestock farming systems in India. Developments discussed in the review in the area of tick vaccines and other tick control measures should have an impact on the future of Indian livestock production.This work has been facilitated through The Integrated Consortium on Ticks and Tick-borne Diseases (ICTTD-3), financed by the International Cooperation Programme of the European Union through Coordination Action Project no. 510561.Peer reviewe

Cloning, expression and immunoprotective efficacy of rHaa86, the homologue of the Bm86 tick vaccine antigen, from Hyalomma anatolicum anatolicum

The Bm86 homologue of Hyalomma anatolicum anatolicum Izatnagar isolate was cloned and expressed in methylotropic yeast Pichia pastoris as intracellular, glycosylated and particulated form. It was named as rHaa86, the first recombinant protein of H. a. anatolicum. Seven epidermal growth factor-like domains predicted in Haa86 were structurally similar with that of its Bm86 counterpart. The identity between the corresponding EGF like domains of Bm86 and Haa86 were ranging from 51·3% to 78·3%. The molecular weight of the rHaa86 was 120–140 kDa, with possible 50–70 kDa glycosylation. The purified rHaa86 was characterized immunologically and evaluated for its immunoprotective potential against homologous challenge infestation in three groups of cross-bred calves. The immediate rejection percentage of females of H. a. anatolicum was 36 5%, 12·4% and 10·1% fed on immunized (group 1), adjuvant control (group 2) and untreated control (group 3) calves, respectively. The percent rejection of female ticks fed on immunized calves was 24·1% and 26·4% higher than for the ticks fed on control groups 2 and 3, respectively (P < 0·05). The reduction of number of females, mean weight of eggs, adult females and efficacy of immunogen were 58·0%, 9·0%, 5·0% and 61·6%, respectively. The mean reproductive index of females fed on group 1 calves was significantly lower (P < 0·05) than the females fed on the control groups and 44% reduction in the number of engorged larvae was recorded from the group 1 calves. The data demonstrated that rHaa86 antigen based vaccine could serve as one of the effective components in the integrated control of H. a. anatolicum.Authors are grateful to Indian Council of Agricultural Research, New Delhi for providing research fellowship to the Senior author. Sincere thanks are due to Department of Biotechnology, Government of India for providing financial support. This work has been facilitated through the Integrated Consortium on Ticks and Tick-borne Diseases (ICTTD-3), financed by the International Cooperation Programme of the European Union through Coordination Action Project no. 510561.Peer reviewe

Cost effectiveness of colony lysis and colony PCR methods for screening of recombinant <i style="">Escherichia coli</i> colonies ¾ A comparative study

731-735Economizing the research protocols by using low cost technologies is the need of laboratories of developing world. Screening of recombinant E. coli colonies is the crucial step in gene cloning and expression studies. In the present study, the cost effectiveness of colony lysis method and colony PCR method in the screening of recombinant E. coli colonies was compared. The colony lysis method was 20 two times more cost effective and less time consuming and can be used to screen the recombinant E. coli colonies in large scale instead of colony PCR method

Molecular comparison of cattle fever ticks from native and introduced ranges, with insights into optimal search areas for classical biological control agents

Cattle fever ticks, the southern cattle tick, Rhipicephalus microplus (Canestrini), and cattle tick, Rhipicephalus annulatus (Say), are livestock pests endemic to Mexico and invasive along the Texas-Mexico border. Resistance to acaricide, alternate wildlife hosts, and pathogenic landscape-forming weeds present challenges for sustainable eradication of this pest in the U.S. Classical biological control is being explored as a strategy to control cattle fever ticks, especially on alternate hosts such as nilgai antelope, Boselaphus tragocamelus (Pallas), and white-tailed deer, Odocoileus virginianus (Zimmermann). Molecular genetic tools were used to compare populations of cattle fever ticks from native and introduced ranges to provide insights into optimal search areas for potential biological control agents. Accessions representative of invasive populations of southern cattle tick from subtropical Zapata, TX, and other parts of the invaded range including Brazil and Kenya matched most closely populations in Cambodia and the Philippines. Similarly, accessions of cattle tick from invaded range in Del Rio, TX matched closely with accessions from native range in Bulgaria and Romania. These regions should be prioritized for field exploration for biological control agents