Efficacy of Rhipicephalus (Boophilus) microplus Bm86 against Hyalomma dromedarii and Amblyomma cajennense tick infestations in camels and cattle.

The recombinant Bm86-based tick vaccines have shown their efficacy for the control of cattle ticks, Rhipicephalus (Boophilus) microplus and R. annulatus infestations. However, cattle ticks often co-exist with multi-host ticks such as Hyalomma and Amblyomma species, thus requiring the control of multiple tick infestations for cattle and other hosts. Vaccination trials using a R. microplus recombinant Bm86-based vaccine were conducted in cattle and camels against Hyalomma dromedarii and in cattle against Amblyomma cajennense immature and adult ticks. The results showed an 89% reduction in the number of H. dromedarii nymphs engorging on vaccinated cattle, and a further 32% reduction in the weight of the surviving adult ticks. In vaccinated camels, a reduction of 27% and 31% of tick engorgement and egg mass weight, respectively was shown, while egg hatching was reduced by 39%. However, cattle vaccination with Bm86 did not have an effect on A. cajennense tick infestations. These results showed that Bm86 vaccines are effective against R. microplus and other tick species but improved vaccines containing new antigens are required to control multiple tick infestations.

Rodríguez-Valle M ，Taoufik A ，Valdés M ，Montero C ，Ibrahin H ，Hassan SM ，Jongejan F ，de la Fuente J ... -  《-》

Efficacy of Hyalomma scupense (Hd86) antigen against Hyalomma excavatum and H. scupense tick infestations in cattle.

The Rhipicephalus microplus recombinant Bm86-based tick vaccines have shown their efficacy for the control of several Hyalomma cattle ticks genera, namely H. dromedarii and H. anatolicum. However, H. scupense species, the most important tick in North Africa has never been studied. Vaccination trials using either a recombinant Bm86-based vaccine or a recombinant Hd86-based vaccine (the Bm86 ortholog in H. scupense) were conducted in cattle against immature and adult H. scupense ticks and adult H. excavatum ticks. The results showed a 59.19% reduction in the number of scupense nymphs engorging on Hd86 vaccinated cattle. However, cattle vaccination with Bm86 or Hd86 did not have an effect on H. scupense or H. excavatum adult ticks infestations. These results showed that Hd86 vaccines are selectively effective against H. scupense immature instars and emphasize on an integrated anti-tick vaccine control in North Africa.

Galaï Y ，Canales M ，Ben Saïd M ，Gharbi M ，Mhadhbi M ，Jedidi M ，de La Fuente J ，Darghouth MA ... -  《-》

Two initial vaccinations with the Bm86-based Gavacplus vaccine against Rhipicephalus (Boophilus) microplus induce similar reproductive suppression to three initial vaccinations under production conditions.

Vargas M ，Montero C ，Sánchez D ，Pérez D ，Valdés M ，Alfonso A ，Joglar M ，Machado H ，Rodríguez E ，Méndez L ，Lleonart R ，Suárez M ，Fernández E ，Estrada MP ，Rodríguez-Mallón A ，Farnós O ... -  《BMC Veterinary Research》

Molecular characterization of Bm86 gene orthologs from Hyalomma excavatum, Hyalomma dromedarii and Hyalomma marginatum marginatum and comparison with a vaccine candidate from Hyalomma scupense.

The ixodid ticks from the Hyalomma genus are important pests of livestock, having major medical and veterinary significance in Northern Africa. Beside their direct pathogenic effects, these species are vectors of important diseases of livestock and in some instances of zoonoses. Anti-tick vaccines developed in Australia and Cuba based on the concealed antigen Bm86 have variable efficacy against H. anatolicum and H. dromedarii. This variation in vaccine efficacy could be explained by the variability in protein sequence between the recombinant Bm86 vaccine and Bm86 orthologs expressed in different Hyalomma species. Bm86 orthologs from three Hyalomma tick species were amplified in two overlapping fragments and sequenced. The rate of identity of the amino acid sequence of Hm86, He86 and Hdr86, the orthologs of Bm86, respectively, in H. marginatum marginatum, H. excavatum and H. dromedarii, with the Bm86 proteins from Rhipicephalus microplus (Australia, Argentina and Mozambique) ranged between 60 and 66%. The obtained amino-acid sequences of Hmm86, He86 and Hdr86 were compared with the Hd86-A1 sequence from H. scupense used as an experimental vaccine. The results showed an identity of 91, 88 and 87% for Hmm86, He86 and Hdr86, respectively. A specific program has been used to predict B cells epitopes sites. The comparison of antigenic sites between Hd86-A1 and Hm86/Hdr86/He86 revealed a diversity affecting 4, 8 and 12 antigenic peptides out of a total of 28 antigenic peptides, respectively. When the Bm86 orthologs amplification protocol adopted in this study was applied to H. excavatum, two alleles named He86p2a1 and He86p2a2 were detected in this species. This is the first time that two different alleles of Bm86 gene are recorded in the same tick specimen. He86p2a1 and He86p2a2 showed an amino acid identity of 92%. When He86p2a1 and He86p2a2 were compared to the corresponding sequence of Hd86-A1 protein, an identity of 86.4 and 91.0% was recorded, respectively. When compared to He86, Hdr86 and Hm86, Bm86 used in commercial and experimental vaccines, showed a greater extent of diversity than noted when the same Hyalomma orthologs were compared to Hd86-A1. Although significant, these variations were less extensive within the Hyalomma genus. Accordingly, thus suggesting that Hd86-A1 vaccine candidate might be more appropriate to target Hyalomma tick species than corresponding Bm86 commercial vaccines. However, vaccination trials with both antigens are required to validate this hypothesis.

Ben Said M ，Galai Y ，Mhadhbi M ，Jedidi M ，de la Fuente J ，Darghouth MA ... -  《-》

Vaccination with recombinant Boophilus annulatus Bm86 ortholog protein, Ba86, protects cattle against B. annulatus and B. microplus infestations.

Canales M ，Almazán C ，Naranjo V ，Jongejan F ，de la Fuente J ... -  《BMC BIOTECHNOLOGY》