Tick vitellogenin receptor reveals critical role in oocyte development and transovarial transmission ofBabesiaparasite
Damdinsuren BoldbaatarBadgar BattsetsegTomohide MatsuoTakeshi HattaRika Umemiya‐ShirafujiXuenan XuanKozo Fujisaki
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Abstract:
A cDNA encoding the vitellogenin receptor of the ixodid tick, Haemaphysalis longicornis Neumann (HlVgR) was cloned and characterized. The full-length cDNA is 5631 bp, including an intact ORF encoding an expected protein with 1782 amino acids. The deduced amino acid sequence of the HlVgR cDNA revealed two ligand-binding domains with four class A cysteine-rich repeats in the first domain and eight in the second domain similar to those of insect VgRs. The immunoblot analysis detected ~197 kDa protein in both tick ovary and egg. The developmental expression profile demonstrated that HlVgR mRNA exists throughout the ovarian development, and the transcriptional level is especially high in the previtellogenic period. Immuno electron microscopy analysis demonstrated that the localization of HlVgR is detected on the external surface of oocyte plasma membrane. RNAi showed that eggs of HlVgR dsRNA-injected adult ticks had not developed into fully mature oocytes and laid abnormal eggs. The Babesia parasite DNA was not detected in the eggs of HlVgR dsRNA-injected tick that fed on Babesia gibsoni infected dog, whereas it was detected in the eggs of PBS-injected ticks and noninjected ticks. Expression of HlVgR was increased by the vitellogenic hormone 20-hydroxyecdysone. These results indicate that HlVgR, which is produced by the developing oocytes, is essential for Vg uptake, egg development in the H. longicornis tick, and transovarial transmission of Babesia parasites.Keywords:
Haemaphysalis longicornis
Vitellogenin
Transovarial transmission
Babesia bigemina
Ecdysone receptor
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A cDNA encoding the vitellogenin receptor of the ixodid tick, Haemaphysalis longicornis Neumann (HlVgR) was cloned and characterized. The full-length cDNA is 5631 bp, including an intact ORF encoding an expected protein with 1782 amino acids. The deduced amino acid sequence of the HlVgR cDNA revealed two ligand-binding domains with four class A cysteine-rich repeats in the first domain and eight in the second domain similar to those of insect VgRs. The immunoblot analysis detected ~197 kDa protein in both tick ovary and egg. The developmental expression profile demonstrated that HlVgR mRNA exists throughout the ovarian development, and the transcriptional level is especially high in the previtellogenic period. Immuno electron microscopy analysis demonstrated that the localization of HlVgR is detected on the external surface of oocyte plasma membrane. RNAi showed that eggs of HlVgR dsRNA-injected adult ticks had not developed into fully mature oocytes and laid abnormal eggs. The Babesia parasite DNA was not detected in the eggs of HlVgR dsRNA-injected tick that fed on Babesia gibsoni infected dog, whereas it was detected in the eggs of PBS-injected ticks and noninjected ticks. Expression of HlVgR was increased by the vitellogenic hormone 20-hydroxyecdysone. These results indicate that HlVgR, which is produced by the developing oocytes, is essential for Vg uptake, egg development in the H. longicornis tick, and transovarial transmission of Babesia parasites.
Haemaphysalis longicornis
Vitellogenin
Transovarial transmission
Babesia bigemina
Ecdysone receptor
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Babesia bigemina
Transovarial transmission
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Haemaphysalis longicornis
Blood meal
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Abstract Jingmen tick virus (JMTV) is a novel tick‐borne virus first identified from Jingmen city, Hubei Province of China in 2010. It has been proved that JMTV can cause human diseases and is widely distributed both inside and outside of China. However, the survival mode and transmission characteristics of JMTV still need further research, particularly in terms of transovarial transmission. In this study, an investigation was conducted to explore the presence of JMTV from engorged female ticks to their offspring. All engorged female adult ticks were collected from domestic cattle and allowed to lay eggs in appropriate humidity and temperature conditions. Maternal ticks, eggs and larvae were screened for JMTV RNA through real‐time polymerase chain reaction (RT‐PCR) and nested PCR methods. The results revealed the positive rate of 10.53% (10/95) in engorged ticks, 9.09% (2/22) in eggs and 8% (4/50) in larvae pools, respectively. Phylogenetic analysis confirmed that sequences from eggs and larvae had closer relationship with those isolates from maternal engorged ticks with more than 99.7% homology and JMTV manifested with evolutional conservatism. Our study has identified for the first time that JMTV could be transmitted from mother generation to offspring of Haemaphysalis Longicornis . Nonetheless, the efficiency of transovarial transmission in JMTV and the significance of ticks as amplification hosts still need to be further illustrated.
Haemaphysalis longicornis
Transovarial transmission
Haemaphysalis
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Haemaphysalis longicornis
Babesia bigemina
Babesia bovis
Theileria
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We studied the tick, Haemaphysalis longicornis, to determine the possibility of both transovarial and transstadial transmission of Babesia equi. We also studied the usefulness of the needle injection method for pathogenic tick-transmitted organisms including Babesia parasites. Erythrocytes infected with B. equi were injected into the midgut of engorged adults or nymphs using a hypodermic needle passed through the integument. DNA of B. equi in ticks was detected using nested polymerase chain reaction (PCR). B. equi DNA was present in adults, eggs, and larvae, indicating that transovarial transmission occurred. B. equi DNA was present in adults that developed from infected nymphs, and the B. equi antigen was present in their salivary glands, indicating that transstadial transmission occurred. These findings suggest that H. longicornis may play a role in the transmission of B. equi.
Haemaphysalis longicornis
Transovarial transmission
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20-hydroxyecdysone (20E), a naturally occurring ecdysteroid hormone in arthropods, was administered by injection to female Haemaphysalis longicornis ticks that were partially fed virgin ticks or replete and mated to assess its effect on vitellogenesis. Injection of 20E into the partially fed virgin ticks stimulated vitellogenesis, as determined by significant increases in ovary development, increased amount of vitellogenin (Vg) in fat body, haemolymph Vg accumulation, and ovarian vitellin (Vn) accumulation. Replete mated ticks injected with 20E showed no differences from untreated ticks in the ovary weights or concentrations of fat body Vg, haemolymph Vg, and ovarian Vn. These results demonstrated that 20E administration stimulated vitellogenesis in partially fed virgin ticks but had no effect on replete mated ticks. The implications of these findings on the regulation of vitellogenesis in H. longicornis are discussed.
Vitellogenin
Hemolymph
Haemaphysalis longicornis
Ecdysteroid
20-Hydroxyecdysone
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Bovine babesiosis is responsible for serious economic losses in Uruguay. Haemovaccines play an important role in disease prevention, but concern has been raised about their use. It is feared that the attenuated Babesia bovis and Babesia bigemina vaccine strains may be transmitted by the local tick vector Boophilus microplus, and that reversion to virulence could occur. We therefore investigated the possibility that these strains could be transmitted via the transovarial route in ticks using a Babesia species-specific polymerase chain reaction (PCR) assay. DNA was extracted from the developmental stages of the tick vector that had fed on calves immunized with the haemovaccine. It was possible to detect Babesia DNA not only in adult ticks, but also in their eggs and larvae. In addition, it was shown that calves infested with larvae derived from eggs laid by ticks fed on acutely infected calves, were positive for Babesia using PCR. Caution should therefore be shown with the distribution of the haemovaccine in marginal areas. It is still advisable that suitable tick control measures be used to prevent transovarial transmission and the potential risk of attenuated Babesia reverting to virulence.
Babesia bigemina
Babesia bovis
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Abstract We demonstrated experimental acquisition and transmission of Heartland bandavirus by Haemaphysalis longicornis ticks. Virus was detected in tick salivary gland and midgut tissues. A total of 80% of mice exposed to 1 infected tick seroconverted, suggesting horizontal transmission. H. longicornis ticks can transmit the virus in the transovarial mode.
Haemaphysalis longicornis
Transovarial transmission
Argasidae
Horizontal transmission
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Transovarial transmission of a newly isolated large intraerythrocytic parasite, Babesia sp. 1 by Haemaphysalis longicornis was experimentally demonstrated. Larvae of H. longicornis were transovarially infected with the parasite by feeding as adults on the calf which had been experimentally infected with B. sp. 1. Piroplasms of B. sp. 1 were observed in peripheral blood of the calf which was infested with the parasite-infected larvae. Based on the transmissibility of the parasite with vector ticks, this parasite was suggested to be a variety of B. ovata. Thus, we propose a new variety name for B. sp. 1 as B. ovata oshimensis n. var.
Haemaphysalis longicornis
Transovarial transmission
Haemaphysalis
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