Immunomic Investigation of Holocyclotoxins to Produce the First Protective Anti-Venom Vaccine Against the Australian Paralysis Tick, Ixodes holocyclus

Apparent tick paralysis by Otobius megnini in a cat

In this study, we report a rare case of tick paralysis in a cat induced by Otobius megnini infestation. An 11-month-old female cat was admitted to a private veterinary clinic in Luling Texas, USA presenting with depression, tachycardia, and flaccid paralysis of the entire body. The four recovered ticks were morphologically and molecularly identified as O. megnini nymphs. Following initial tick removal and treatment with 0.1% milbemycin oxime in the ear canal on the first day of hospitalization, and additional tick removal and topical selamectin treatment on the second day of hospitalization the animal gradually improved. The recovery of the cat after tick removal supports the diagnosis of tick toxicosis. While tick antiserum is not available in North America, prevention of tick infestation and tick-induced paralysis can be effectively accomplished using repellent collars and the compliant use of other ectoparasiticide products year-round.

Prospective Study of 506 Dogs with Tick Paralysis: Investigating Measures of Severity and Clinical Signs as Predictors of Mortality and Assessing the Benefits of Different Therapeutics

Survey data from 42 Australian eastern seaboard veterinary practices involving 506 cases are reported with regard to clinical signs, disease severity, mortality, use of pharmaceuticals, and recovery times. New measures of disease severity (visual analogue scales (VAS) and facial expressions) were tested alongside "gold standard" measures (neuromuscular junction (NMJ) scores). Univariable and multivariable logistic regression analyses were conducted to evaluate associations between variables. The VAS scores were progressive, prognostic (especially the respiratory scores) and correlated with the NMJ scores. The presence of inspiratory dyspnoea and crackles on the day of hospitalisation, progressing to expiratory dyspnoea and an expiratory wheeze 24 h later, were highly predictive of mortality. Altered facial features on hospital admission were also highly predictive of mortality. The previously used respiratory score (using various clinical signs) was not predictive of mortality. Older animals had a higher mortality rate, and no gender or breed susceptibility was found. The only pharmaceuticals that were positively associated with mortality were tick antiserum and, in severe cases, antibiotics. The use of many pharmaceutical products (acepromazine, atropine, steroids, antihistamines, antiemetics, diuretics, and S8 anti-anxiety and sedation drugs) had no effect on mortality. More drug classes were used with increasing clinical severity and specific factors (e.g., vomiting/retching, hydration) affected the period of hospitalisation. Geographic variation in respiratory signs and toxicity scores was evident, whereas mortality and disease severity were not different across regions.

Innovative approaches for the control of ticks and tick-borne diseases

Ticks and tick-borne diseases constitute a major threat for human and animal health worldwide. Vaccines for the control of tick infestations and transmitted pathogens still represents a challenge for science and health. Vaccines have evolved with antigens derived from inactivated pathogens to recombinant proteins and vaccinomics approaches. Recently, vaccines for the control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have shown the efficacy of new antigen delivery platforms. However, until now only two vaccines based on recombinant Bm86/Bm95 antigens have been registered and commercialized for the control of cattle-tick infestations. Nevertheless, recently new technologies and approaches are under consideration for vaccine development for the control of ticks and tick-borne pathogens. Genetic manipulation of tick commensal bacteria converted enemies into friends. Frankenbacteriosis was used to control tick pathogen infection. Based on these results, the way forward is to develop new paratransgenic interventions and vaccine delivery platforms for the control of tick-borne diseases.

The Need for Next-Generation Antivenom for Snakebite Envenomation in India

The limitations posed by currently available antivenoms have emphasized the need for alternative treatments to counteract snakebite envenomation. Even though exact epidemiological data are lacking, reports have indicated that most global snakebite deaths are reported in India. Among the many problems associated with snakebite envenomation, issues related to the availability of safer and more efficient antivenoms are of primary concern. Since India has the highest number of global snakebite deaths, efforts should be made to reduce the burden associated with snakebite envenoming. Alternative methods, including aptamers, camel antivenoms, phage display techniques for generating high-affinity antibodies and antibody fragments, small-molecule inhibitors, and natural products, are currently being investigated for their effectiveness. These alternative methods have shown promise in vitro, but their in vivo effectiveness should also be evaluated. In this review, the issues associated with Indian polyvalent antivenoms in neutralizing venom components from geographically distant species are discussed in detail. In a nutshell, this review gives an overview of the current drawbacks of using animal-derived antivenoms and several alternative strategies that are currently being widely explored.

Extended characterisation of five archival tick-borne viruses provides insights for virus discovery in Australian ticks

Background

A subset of Australians who have been bitten by ticks experience a complex of chronic and debilitating symptoms which cannot be attributed to the known pathogenic species of bacteria present in Australia. As a result, there has been a renewed effort to identify and characterise viruses in Australian terrestrial ticks. Recent transcriptome sequencing of Ixodes and Amblyomma ticks has revealed the presence of multiple virus sequences. However, without virus isolates our ability to understand the host range and pathogenesis of newly identified viruses is limited. We have established a successful method for high-throughput virus discovery and isolation in mosquitoes using antibodies to double-stranded RNA. In this study we sought to characterise five archival tick-borne viruses to adapt our virus discovery protocol for Australian ticks.

Methods

We performed virus characterisation using a combination of bioinformatic sequence analysis and in vitro techniques including replication kinetics, antigenic profiling, virus purification and mass spectrometry.

Results

Our sequence analysis of Nugget virus, Catch-me-Cave virus and Finch Creek virus revealed marked genetic stability in isolates collected from the same location approximately 30 years apart. We demonstrate that the Ixodes scapularis-derived ISE6 cell line supports replication of Australian members of the Flaviviridae, Nairoviridae, Phenuiviridae and Reoviridae families, including Saumarez Reef virus (SREV), a flavivirus isolated from the soft tick Ornithodoros capensis. While antibodies against double-stranded RNA could be used to detect replication of a tick-borne reovirus and mosquito-borne flavivirus, the tick-borne flaviviruses Gadgets Gully virus and SREV could not be detected using this method. Finally, four novel virus-like sequences were identified in transcriptome sequencing of the Australian native tick Ixodes holocyclus.

Conclusions

Genetic and antigenic characterisations of archival viruses in this study confirm that three viruses described in 2002 represent contemporary isolates of virus species first identified 30 years prior. Our findings with antibodies to double-stranded RNA highlight an unusual characteristic shared by two Australian tick-borne flaviviruses. Finally, comparative growth kinetics analyses of Australian tick-borne members of the Flaviviridae, Nairoviridae, Phenuiviridae and Reoviridae families in ISE6 and BSR cells will provide a useful resource for isolation of Australian tick-borne viruses using existing cell lines.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05176-z.

Immune responses and inorganic ion transport regulations of Epinephelus coioides in response to L321_RS13075 gene of Pseudomonas plecoglossicida

Pseudomonas plecoglossicida is a well-known pathogen of viscera granulomas disease in fish, which has led to severe economic losses. In our previous study, L321_RS13075 was predicted to be a key virulence gene of P. plecoglossicida during the host-pathogen interaction with Epinephelus coioides. To investigate the role of L321_RS13075 in the regulation of virulence in P. plecoglossicida, a L321_RS13075 knock-down strain was constructed. And a significant reduction in the ability of colonization, intracellular survival, motility, biofilm formation, and adhesion was detected in the L321_RS13075 knock-down strain. Compared with the wild-type strain, the silence of L321_RS13075 in P. plecoglossicida resulted in a significant change in the transcriptome of infected Epinephelus coioides (E. coioides). Results of COG and GO analysis on E. coioides showed that genes related to immune responses and inorganic ion transport were significantly affected by L321_RS13075 of P. plecoglossicida. Meanwhile, the interactions of the genes related to immune responses and inorganic ion transport were predicted, and the important hub genes were identified. Taken together, the results indicated that L321_RS13075 was a virulent gene of P. plecoglossicida, which significantly affected the immune responses and inorganic ion transport in E. coioides.