Rabbit Populations Research Articles

Occurrence of Encephalitozoon cuniculi and Encephalitozoon hellem in European Wild Rabbits (Oryctolagus cuniculus) in Southern Germany (Bavaria)

Encephalitozoon cuniculi and Encephalitozoon hellem are fungus-related, obligate intracellular pathogens belonging to the microsporidia. Both microorganisms occur in mammals, birds and even humans, thus revealing a zoonotic potential. Knowledge of their relevance in wild rabbits is very limited so far. Thus, the aim of the present study was to investigate the occurrence of E. cuniculi and E. hellem in wild rabbit populations in southern Germany (Bavaria). Therefore, blood and organ samples (brain/kidney) of 158 wild rabbits were investigated by immunofluorescence and PCR-based assays. Antibodies to E. cuniculi were detected in 24 of the 158 (15.2%) wild rabbits, while DNA of E. cuniculi was found in 7 (4.4%) and DNA of E. hellem was found in 3 (1.9%). Sequencing identified E. cuniculi genotype 1. This study provides the first E. cuniculi genotype determination in free-living wild rabbits worldwide and the first evidence of E. hellem in rabbits worldwide. Wild rabbits should, therefore, be regarded as a reservoir for both pathogens and, on the basis of molecular evidence from kidney tissue and presumed urine excretion, also as a source of infection for E. cuniculi for animals and humans.

RHDV2 outbreak reduces survival and juvenile recruitment, causing European rabbit population collapse

AbstractInfectious diseases can cause considerable mortality in vertebrate populations, especially when a new pathogen emerges. Quantifying the impact of diseases on wild populations and dissecting the underlying mechanisms requires longitudinal individual monitoring combining demographic and epidemiologic data. Such longitudinal population studies are rare. Rabbit hemorrhagic disease (RHD) is one of the main causes of the decline in European wild rabbit (Oryctolagus cuniculus) populations. A new genotype of RHD virus (RHDV), called RHDV2 or GI.2, emerged in 2010, posing a new threat to previously weakened populations, particularly as this virus can infect individuals already immune to classical RHDV strains. Taking advantage of intensive monitoring from 2009 to 2014 by physical captures and microchip detections of a semi‐captive population of rabbits, we finely assessed the demographic impact of an initial RHDV2 outbreak that occurred in the population and identified the most affected demographic parameters. A multi‐event modeling analysis revealed decreased survival in both juveniles and adults in 2011 and 2012, suggesting an RHDV2 outbreak for two consecutive years. The short‐term survival benefit of vaccination against classical RHDV strains only during these years, and the recovery of carcasses with RHDV2 detection, supported this hypothesis. Variations in population vaccination coverage also explain the difference in adult survival between the two years of the outbreak. And the transient protective effect of vaccination could explain the prolonged duration of the outbreak. A brief episode of myxomatosis in 2011 seems to have had only a limited impact on the population. During outbreak years, in individuals not recently vaccinated, monthly juvenile survival crashed (0.55), and annual adult survival was three times lower than in normal years (0.21 vs. 0.69). The combination of successive juvenile and adult survival estimates for unvaccinated rabbits during the outbreak years resulted in a very low recruitment rate in the breeding population. Finally, RHDV2 outbreaks appear to have caused mortalities comparable to those caused by older classical RHDV strains and may have a strong demographic impact on wild populations of European rabbit. This work highlights the importance of long‐term observational and experimental studies to better understand the impact of epidemics on animal populations.

Absence of Crimean-Congo hemorrhagic fever virus in wild lagomorphs and their ticks in Spanish Mediterranean ecosystems

Crimean-Congo hemorrhagic fever virus (CCHFV) is an emerging tick-borne pathogen in different European countries. Since 2013, clinical and fatality cases associated with CCHFV infection have been reported in humans in Spain. During the last few years, endemic circulation of this virus has been detected in ticks and wild ungulates in this country, but the role of other sympatric wild species in the sylvatic cycle of this multi-host virus remains poorly understood. The aims of the present study were to assess exposure to CCHFV in wild lagomorphs in southern Spain, a CCHFV endemic area, and to determine the presence of the virus in ticks feeding on these species. Serum samples from 473 European wild rabbits (Oryctolagus cuniculus) and 162 Iberian hares (Lepus granatensis), and 120 ticks feeding on 85 of these wild lagomorphs were collected on 133 hunting grounds between 2018/2019 and 2021/2022 hunting seasons. The presence of antibodies against CCHFV was assessed in all serum samples using a commercial ELISA, whereas ticks were tested for the presence of CCHFV-RNA by a multiplex RT-qPCR that detects all known genotypes of this virus. None of the 635 (0.0 %; 95 %CI: 0.0–0.6) lagomorphs tested had anti-CCHFV antibodies and CCHFV-RNA was not found in any of the 120 (0.0 %; 95 %CI: 0.0–3.0) ticks analyzed. To the best of the authors knowledge, this is the first epidemiological study conducted on CCHFV in Iberian hare worldwide. Our findings indicate absence of exposure to CCHFV in European wild rabbit and Iberian hare populations, as well as in their ticks, which suggests that they do not seem to play a relevant role in the epidemiology of CCHFV in Mediterranean ecosystems of southern Spain.

Selection against domestication alleles in introduced rabbit populations.

Humans have moved domestic animals around the globe for thousands of years. These have occasionally established feral populations in nature, often with devastating ecological consequences. To understand how natural selection shapes re-adaptation into the wild, we investigated one of the most successful colonizers in history, the European rabbit. By sequencing the genomes of 297 rabbits across three continents, we show that introduced populations exhibit a mixed wild-domestic ancestry. We show that alleles that increased in frequency during domestication were preferentially selected against in novel natural environments. Interestingly, causative mutations for common domestication traits sometimes segregate at considerable frequencies if associated with less drastic phenotypes (for example, coat colour dilution), whereas mutations that are probably strongly maladaptive in nature are absent. Whereas natural selection largely targeted different genomic regions in each introduced population, some of the strongest signals of parallelism overlap genes associated with neuronal or brain function. This limited parallelism is probably explained by extensive standing genetic variation resulting from domestication together with the complex mixed ancestry of introduced populations. Our findings shed light on the selective and molecular mechanisms that enable domestic animals to re-adapt to the wild and provide important insights for the mitigation and management of invasive populations.

Molecular detection and association of 12.1kb deletion within the high mobility AT-hook 2 gene in the Netherlands dwarf rabbit (Oryctolagus Cuniculus).

Rabbits are mainly bred for human consumption and medical research. However, it has been recently showed that several rabbit breeds are also kept as pets for human leisure. The Netherlands dwarf rabbit is currently in the immense interest of many Vietnamese customers due to its personality and miniature stature. However, 12.1kb deletion from position 44,709,089 to 44,721,236bp in the high mobility AT-hook 2 (HMGA2) gene on chromosome 4 was identified as the structural variant causing dwarfism and altered craniofacial development in this breed. It has been documented that HMGA2 plays an important role in regulating growth and individuals with genotype HMGA2 del/del are fatal several days after birth. Despite the economically high value of the Netherlands dwarf rabbit, there has been no study on the genetic survey of lethal alleles in this breed in Vietnam. The aim of this study is to develop a fast and reliable method to screen the frequency of lethal alleles of HMGA2 in the South of Vietnam. Rabbit saliva was collected, and DNA extraction was followed. Multiplex polymerase chain reaction (PCR) with three primers was optimized and performed to detect the presence of 12.1kb deletion within the HMGA2 sequence. Our data showed that the 12.1kb deletion in the Netherlands dwarf rabbit population was detected by our optimized multiplex PCR. In 100 rabbit animals, 34 and 16 individuals were homozygous wild type (+/+) and homozygous mutant (del/del), respectively, while 50 rabbits were heterozygous. The frequency of HMGA2 lethal allele carrier was 66% (66/100 individuals). Our results indicated that we successfully developed a fast, accurate multiplex PCR to detect carrier individuals. Verification of the genotypes was followed by sequencing. We recommend implementing our multiplex PCR procedure in genetic selection for carrier and homozygous wild-type animals in the mating scheme to prevent the lethality of the rabbit offspring. Additionally, awareness should be raised among rabbit breeders to monitor the genetic makeup of the Netherlands dwarf rabbit populations. However, due to the limitation of the sample size, more samples should be taken in future studies to obtain the genetic frequency of the HMGA2 lethal allele more accurately.

Unravelling the mechanisms underlying the social interaction effects on the feed efficiency of rabbits

The feed consumption and feeding patterns of group-housed livestock and their productive outputs can be affected by interactions among group members, such as competition for feeder access and aggression. The impact of competition is especially significant when feed restriction is implemented during the fattening stage, a common practice in rabbit farms to reduce mortality from digestive disorders during this period. The overall aim was to quantify the importance of social interaction effects at the genetic and environmental level on feed efficiency, feeding behaviour and social ranking traits in rabbit populations having access to electronic feeders whilst they were housed in groups during fattening. This was done by quantifying novel feeding behaviour (FB) and social ranking (SR) traits and by estimating the genetic parameters and genetic correlations between all combinations of direct and social effects of these traits and residual feed intake (RFI), an indicator of feed efficiency. These effects were estimated in animals fed either ad libitum (AL) or on a time-based feed restriction (R) and were selected for feed efficiency on these feeding regimes for six generations. We found that there were substantial social genetic and social litter effects on RFI and FB traits, manifesting as antagonistic relationships between direct and social genetic effects. These effects were stronger amongst the R, as opposed to the AL animals. Despite these antagonistic relationships, the large social genetic effects resulted in substantial heritable variation available for selection of these traits, and therefore feeding behaviour could be changed by genetic selection, especially for R animals. The indicators of an animal’s SR were also heritable and subject to social genetic effects and therefore may respond to selection. However, the phenotypic population mean would not change, because such traits are context−specific. The animals that took most of the feeding resources and had priority access to the feeder had a higher RFI, that is, they were less efficient, but they made their cage mates more efficient. This is the first time that the genetic correlations between direct effects of RFI and direct effects of FB and SR traits, as well as between social effects of RFI and direct effects of FB traits and SR traits, have been quantified. Results could help to understand the mechanisms by which an animal exerts its influence on the feed efficiency of its cage mates under different feeding regimes and assist in the development of breeding strategies.

Response of the subalpine bunchgrasses to wildfires and its effects in the relative abundance of the volcano rabbit in the Ajusco-Chichinautzin Mountain Range.

The volcano rabbit (Romerolagus diazi) is a lagomorph endemic to the central mountains of the Trans-Mexican Volcanic Belt and is classified as threatened at extinction risk. It is a habitat specialist in bunchgrass communities. The annual wildfires that occur throughout its distribution range are a vulnerability factor for the species. However, the effects of wildfires on volcano rabbit populations are not fully understood. We evaluated the occupancy and change in the volcano rabbit relative abundance index in the burned bunchgrass communities of the Ajusco-Chichinautzin Mountain Range during an annual cycle of wildfire events. Additionally, we assessed the factors that favor and limit occupation and reoccupation by the volcano rabbit using the relative abundance index in burned plots as an indicator of these processes. The explanatory factors for the response of the volcano rabbit were its presence in the nearby unburned bunchgrasses, the height of three species of bunchgrass communities, the proportion of different types of vegetation cover within a 500 m radius around the burned plots, heterogeneity of the vegetation cover, and the extent of the wildfire. Statistical analyses indicated possible reoccupation in less than a year in burned bunchgrass communities adjacent to unburned bunchgrass communities with volcano rabbits. The relative abundance index of volcano rabbits was not favored when the maximum height of the Muhlenbergia macroura bunchgrass community was less than 0.77 m. When the vegetation around the burned plots was dominated by forest (cover >30% of the buffer) and the fire was extensive, the number of latrines decreased per month but increased when the bunchgrass and shrub cover was greater around the burned plots. While the statistical results are not conclusive, our findings indicate a direction for future projects, considering extensive monitoring to obtain a greater number of samples that contribute to consolidating the models presented.

Mitochondrial DNA (mtDNA) genetic variability of cytochrome B gene (CYTB) in three populations of native rabbits in Egypt

The current study aimed to detect the genetic variability of mitochondrial DNA (mtDNA) cytochrome B (CYTB) gene in 80 native Egyptian rabbits (NER) belonging to three populations in three different agriculture regions (Delta, Middle, and Upper Egypt) and also investigate the origin of these breeds by phylogenetic relationship analysis. A total of 62 haplotypes were recorded among the three NER populations. The native Upper Egypt rabbits (NUER) expressed the highest number of haplotypes, mutations, polymorphic sites, and haplotype diversity (23, 55, 51, and 1.00, respectively). While it gave the lowest values of nucleotide diversity (0.0262) and Tajima's D (−0.01435), the percentage of mutual haplotypes was 4.8 % between the Middle and Delta Egypt populations. The phylogenetic analysis showed that there were more separated haplotypes of NUER compared to other populations. The same finding was also observed when supported by 31 sequences of different rabbit breeds retrieved from the GeneBank database. A mutual haplotype was observed between native Delta Egyptian rabbits (NDER) and New Zealand (NWZ) rabbits. The results of this study shed light on the importance of indigenous breeds in rural areas through mtDNA, which contributes to finding sustainable strategies to conserve and improve genetic resources in Egyptian rural areas.

A Review of Chemical Castration in Domestic Animals

This review article discusses the use of numerous chemical agents supplied through various routes to regulate the population of several animal species, including dogs, guinea pigs, rabbits, rams, and rats. While surgery is the safest and most effective procedure, it is also the most expensive. Therefore, non-surgical sterilization methods that would make male sterilization cheap, simple, and quick for sterilizing a large number of male animals in a short amount of time were introduced in an effort to slow down the increase in the animal population effectively.

Temporal activity and detection rates of chilla (Lycalopex griseus) in Tierra del Fuego, Argentina.

Designing mitigation strategies for invasive species requires a clear understanding of their ecology and behaviour. Chilla (or grey fox; Lycalopex griseus) were introduced to Isla Grande de Tierra del Fuego (Tierra del Fuego Island) in 1951 to control European rabbit (Oryctolagus cuniculus) populations. Although this management strategy was unsuccessful, the chilla spread across the island and are now considered invasive. Despite this, there is a lack of research concerning their ecology and behavioural patterns, particularly on the Argentinian side of the island. We assessed the detection rates and temporal activity patterns of chillas using camera traps in the Argentinian region of Tierra del Fuego Island. Chilla had average detection rates of 61.7 (SD ± 33.3, range = 13.5-105.7) per 100 trap nights. Although analysis by clock time suggested cathemeral activity patterns, when analysed by sun time the chillas exhibited distinct nocturnal activity patterns. These findings offer the first information on the detection rates of chilla on the Argentinian side of Tierra del Fuego Island and reveal new insights into their temporal activity patterns, providing an important basis for future research that may aid the development of more effective management and conservation strategies.

Epidemiological surveillance of Leishmania infantum in wild lagomorphs in Spanish Mediterranean ecosystems

Wild lagomorphs play a key epidemiological role as reservoirs of Leishmania infantum, causative agent of the largest outbreak of human leishmaniosis in Europe to date. A large-scale survey study was conducted on wild rabbit (Oryctolagus cuniculus) and Iberian hare (Lepus granatensis) populations in Spanish Mediterranean ecosystems to evaluate the exposure of L. infantum and investigate potential risk factors associated with exposure to this zoonotic parasite. Between 2018 and 2021, a total of 631 wild lagomorphs (471 wild rabbits and 160 Iberian hares) were collected in Andalusia (southern Spain) and tested for antibodies against L. infantum using the indirect fluorescent antibody test (IFAT). Spleen samples from 563 of the wild lagomorphs sampled (441 wild rabbits and 122 Iberian hares) were also evaluated by real-time quantitative PCR (qPCR) for detection of Leishmania kDNA. Exposure to L. infantum (positive by IFAT and/or qPCR) was detected in 56.4 % (356/631; 95 %CI: 52.3–60.3) of the lagomorphs analyzed. Anti-Leishmania antibodies were found in 12.8 % (81/631; 95 %CI: 10.2–15.5) of the animals, and L. infantum kDNA was detected in 59.0 % (332/563; 95 %CI: 54.9–63.0) of the spleen samples tested. Phylogenetic analysis revealed high homology (99.9–100 %) between L. infantum sequences obtained and strains previously isolated from humans in Spain. While apparent seroprevalence was significantly higher in Iberian hares (19.4 %; 95 %CI: 13.3–25.5) compared to wild rabbits (10.6 %; 95 %CI: 7.9–13.4), no significant differences in prevalence were found between wild rabbits (61.0 %; 95 %CI: 56.5–65.6) and Iberian hares (51.6 %; 95 %CI: 42.8–60.5). At least one positive animal was found on 64.8 % (70/108) of the hunting grounds sampled, and a high-risk spatial cluster (P < 0.001) was also identified in central Andalusia. The multivariable analysis identified bioclimatic level (meso-Mediterranean climate) and the presence of goats on hunting grounds as risk factors potentially associated with L. infantum exposure in wild lagomorphs. This study shows high, widespread exposure, but heterogeneous distribution of L. infantum in wild lagomorph populations in Mediterranean ecosystems in southern Spain. The results point to the need to promote integrated surveillance programs for the detection of Leishmania spp. in wild lagomorphs in order to establish effective control measures against human leishmaniosis under a One Health approach.

UPAYA MENINGKATKAN PERTUMBUHAN TERNAK KELINCI DI DASAN KARANG ANYAR DESA SIKUR LOMBOK TIMUR

Service to the community in the village of Karang Anyar Sikur Village, East Lombok, aims to improve knowledge breeders skill especially breeders rabbit that is in through making and giving quality feed. The population and growth of rabbits in Karang Anyar Sikur Village, East Lombok is relatively low compared to other villages in East Lombok, this is due to the lack of knowledge about the management of feeding rabbits, including the quality and quantity of feed provided. The implementation of the activity is carried out gradually, starting from the survey location, setting the time for implementation, making the brochure/leaf, and watching the video about the cultivation of the rabbit and the evaluation stage. By achieving the goal of this activity, it is expected that the community, especially the pet group, will be able to make formulas for the rabbit's food from the materials that are available at the location, with the content of the nutrition, according to the needs of the rabbit, and the provision of good food, so that it can increase the growth of the rabbit Income breeders rabbit.

Patchy Anthropocoasts: A transdisciplinary perspective on dunes, plants, rabbits, and humans in the United Kingdom

In recent years, there has been increasing societal awareness of the crucial role that coastal dunes play in protecting against rising sea levels, mitigating climate change impacts, promoting biodiversity, and providing recreational opportunities. In some regions, dune management has been particularly focused on biodiversity and ecosystem restoration and the presence of alien species on dunes raises concerns about how these species become 'native,' 'invasive,' or 'hybrids' and whether they belong in their new ecosystems. These concerns illustrate how certain animals and plants assume different statuses according to normative categories associated with varying objectives. This article explores how perceptions of coastal dunes in the UK have transformed over time, from marginal resource frontiers to highly valued environments shaped by multispecies relations. In addition, this work explores how dunes around the UK emerge as ‘patchy anthropocoasts,’ that is, uneven landscapes designed by human purposes linked to economic activities, conservation, rabbit populations, unwanted vegetation, and the control of unpredictable sand movements. Bringing together diverse historical materials and scientific literature, this article links human and nonhuman histories with present debates on dune restoration from a transdisciplinary perspective rooted in anthropology, environmental history, and the natural sciences.

Fibonacci Numbers between History, Semiotics, and Storytelling: The Birth of Recursive Thinking

The aim of this paper is to discuss the emergence of recursive thinking through the famous problem posed by Fibonacci regarding the growth of the rabbit population. This paper qualitatively analyzes and discusses the semiotic aspects raised by the students working with this historical source in the form of a story. From this perspective, the value of the historical problems as socio-cultural references (voices) and of the narrations as mediating factors to enhance students’ learning of new mathematical concepts, such as recursion, is explored in depth. The focus lies on the pivotal role played by the students’ construction of personal senses during in-group mathematical activities, in dialectics with the normative and mathematical meanings. It is highlighted that fostering environments conducive to dialogue among peers, as well as linking various shapes and contexts of knowledge, is necessary. Here, storytelling and history are regarded as fruitful resources aiding students in the gradual construction of a personal sense of mathematical concepts, including recursion.

Effect of Weight at First Mating on the Performance of New Zealand White Rabbit Population in the Rainforest Zone of Nigeria

It has been generally accepted that for breeders to embark on intensive production of rabbits there is a need to use appropriate body weight rabbit that has better performance. To provide such information, this study was therefore carried out to determine the effect of weight at first mating on the performance of the New Zealand White rabbit population at the University of Benin Teaching and Research Farm. The rabbits were grouped into four based on their weight before the first service (1.00 to 1.49kg, 1.50 to 1.99kg, 2.00 to 2.49kg, and 2.5kg and above) as weight groups 1, 2, 3, and 4 respectively. The rabbits were raised under acceptable management. The experimental animals were fed a commercial diet of 18% CP and 2700kcal/kg ME. Data collected were weight of doe before service (WBS), number of time served (NTS), litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW), pre-weaning mortality percentage (PWM), gestation length (GLT), and stillbirth (SBT). The data were subjected to statistical analysis using the R statistical package version 3.3.3 (2017). Significant means were separated using the Duncan Multiple Range Test. The results obtained showed an increasing trend with body weight at first service. The mean values for LWB were 40.08±1.04, 43.83±2.16, 49.26±2.93 and 45.57±3.74 g for weight groups 1, 2, 3, and 4, respectively. Rabbits in weight 2 and 3 had a higher CV of 30%. Mean LWW ranged from 366.20±26.92 in group 1 to 442.90±29.74 in weight group 4. The average LSB was 4 kits. Litter sizes at weaning (LSW) were 3 kits except for group 4 with 4 kits. The body weight at first mating had no significant effect (P&amp;gt;0.05) on the performance traits. Gestation length (GLT) and pre-weaning mortality (PWM) showed significance (P&amp;lt;0.05). Gestation length (GLT) was highest in weight group 4 with mean days of 32.14±0.40 and the least in group 3 (30.53±0.09). Percentage SBT was highest in group 3 (10.48%) and none was recorded in group 4, 0.00±0.00. Percentage PWM was highest in groups 1 and 2 with 23.25% and 1.50%, respectively, while there was no PWM recorded in groups 3 and 4. The results of the efficiency of gain of offspring from the weight group were not significantly different (P&amp;gt;0.05) except for mortality which showed a significant difference (P&amp;lt;0.05). Rabbits from weight groups 1 and 3 showed better performance but for the high mortality in group 1, it will be better to mate rabbits for the first time at weight group 3.

Unlocking the potential of local rabbit population: morphological insights for sustainable rabbit farming in Burkina Faso’s challenging environments

This study explores the potential of rabbits as a sustainable solution for poverty alleviation and food security in Burkina Faso, a country facing socio-economic and environmental challenges. In the context of limited resources and employment opportunities, rabbits offer advantages such as small size, short generation interval and high reproductive capacity. The research focuses on characterising the morphology of Burkina Faso’s local rabbit population, comparing it with two Italian breeds: a local medium-growing breed called Leprino di Viterbo (LV) and a fast-growing hybrid (a crossbred New Zealand × California, NZC). Utilising path analysis and principal component analysis, the study identifies key morphometric traits crucial for breeding programs and examines the influence of specific traits on body weight (BW) gain and heat stress resilience through ‘Transpiration Indexes.’ Findings highlight the importance of variables like chest girth (CG), abdominal girth (AG), rump width (RW) and nose to shoulders length (NSL) in influencing body weight (BW) and reveal significant size and shape differences among the breeds. The study suggests potential climate adaptation in Burkina Faso’s rabbit population, providing practical insights for breeding programs in resource-constrained regions. This research not only advances scientific understanding but also provides practical insights for breeding programs in resource-constrained regions, emphasising the importance of certain morphological traits for heat dissipation.

Effects of diet on the bacterial and eukaryotic microbiota across the gastrointestinal tract of healthy rabbits (Oryctolagus cuniculus).

This study aimed to characterize the bacterial and eukaryotic microbiota of the gastrointestinal (GI) tract in domestic rabbits and to evaluate the effect of different diet characteristics, such as pelleting, extrusion, and hay supplementation. 30 New Zealand White rabbits (15 male and 15 female; 6 to 7 months old) were fed 1 of 6 diets (5 rabbits per diet) for 30 days after an initial acclimation period. At the end of the trial, samples were collected from the stomach, small intestine, cecum, large intestine, and hard feces. The samples were analyzed using 16S rRNA and internal transcribed spacer 1 region-targeted amplicon sequencing. The bacterial microbiota was distinct between the foregut and hindgut. The most abundant bacterial genera included an unclassified genus in the Bacteroidales order and Alistipes. Candida was the most abundant genus in the eukaryotic dataset. In the bacterial dataset, diet No Hay/Pellet E was shown to have lower diversity (Shannon diversity, P < .05) compared to all diet groups except for No Hay/Pellet M. Few significant differences in alpha-diversity indexes between diet groups were detected in the eukaryotic dataset. Our findings demonstrated that feeding hay had a significant effect on the beta diversity of the bacterial microbiota. Given the prevalence of gastrointestinal disease in the domestic rabbit population, furthering our understanding of what constitutes a healthy rabbit microbiota and the effects of different diets on the microbial community can help veterinarians implement better intervention strategies and allow pet owners to provide the best level of care.

Vaccination against Rabbit Hemorrhagic Disease Virus 2 (RHDV2) Using a Baculovirus Recombinant Vaccine Provides Durable Immunity in Rabbits.

Rabbit hemorrhagic disease virus 2 (RHDV2) emerged in the United States in 2018 and has spread in both domestic and wild rabbits nationwide. The virus has a high mortality rate and can spread rapidly once introduced in a rabbit population. Vaccination against RHDV2 provides the best protection against disease and should be considered by all rabbit owners. Here, we investigate the duration of immunity provided by vaccination with the Medgene Platform conditionally licensed commercial vaccine 6 months following the initial series. Rabbits received either the vaccination or a placebo and were challenged with RHDV2 6 months later. All vaccinated rabbits survived challenge whereas 18/19 non-vaccinated controls succumbed to infection within 10 or fewer days post-challenge. These results demonstrate lasting immunity following vaccination with the Medgene RHDV2 vaccine.

Epidemiological characterization and risk assessment of rabbit haemorrhagic disease virus 2 (RHDV2/b/GI.2) in the world

A novel variant of rabbit haemorrhagic disease virus, designated RHDV2/b/GI.2, was first discovered in France in 2010. Subsequently, RHDV2 rapidly spread to Africa, North America, Australia, and Asia. RHDV2 outbreaks have resulted in significant economic losses in the global rabbit industry and disrupted the balance of natural ecosystems. Our study investigated the seasonal characteristics of RHDV2 outbreaks using seasonal indices. RHDV2 is prone to causing significant outbreaks within domestic and wild rabbit populations during the spring season and is more likely to induce outbreaks within wild rabbit populations during late autumn in the Southern Hemisphere. Furthermore, based on outbreak data for domestic and wild rabbits and environmental variables, our study established two MaxEnt models to explore the relationship between RHDV2 outbreaks and the environmental factors and conducted outbreak risk predictions for RHDV2 in global domestic and wild rabbit populations. Both models demonstrated good predictive performance, with AUC values of 0.960 and 0.974, respectively. Road density, isothermality, and population density were identified as important variables in the outbreak of RHDV2 in domestic rabbits, while road density, normalized difference vegetation index, and mean annual solar radiation were considered key variables in the outbreak of RHDV2 in wild rabbits. The environmental factors associated with RHDV2 outbreaks identified in our study and the outbreak risk prediction maps generated in our study will aid in the formulation of appropriate RHDV2 control measures to reduce the risk of morbidity in domestic and wild rabbits.

Neglected Spleen Transcriptional Profile Reveals Inflammatory Disorder Conferred by Rabbit Hemorrhagic Disease Virus 2 Infection.

Rabbit hemorrhagic disease (RHD) is an acute fatal disease caused by the rabbit hemorrhagic disease virus (RHDV). Since the first outbreaks of type 2 RHDV (RHDV2) in April 2020 in China, the persistence of this virus in the rabbit population has caused substantial economic losses in rabbit husbandry. Previous failures in preventing RHDV2 prompted us to further investigate the immune mechanisms underlying the virus's pathogenicity, particularly concerning the spleen, a vital component of the mononuclear phagocyte system (MPS). For this, a previous RHDV2 isolate, CHN/SC2020, was utilized to challenge naive adult rabbits. Then, the splenic transcriptome was determined by RNA-Seq. This study showed that the infected adult rabbits had 3148 differentially expressed genes (DEGs), which were associated with disease, signal transduction, cellular processes, and cytokine signaling categories. Of these, 100 upregulated DEGs were involved in inflammatory factors such as IL1α, IL-6, and IL-8. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these DEGs were significantly enriched in the cytokine-cytokine receptor interaction signaling pathway, which may play a vital role in CHN/SC2020 infection. At the same time, proinflammatory cytokines and chemokines were significantly increased in the spleen at the late stages of infection. These findings suggested that RHDV2 (CHN/SC2020) might induce dysregulation of the cytokine network and compromise splenic immunity against viral infection, which expanded our understanding of RHDV2 pathogenicity.