Growth performance of three paternal rabbit lines with different potential for growth rate and resilience

[EN] This experiment aimed to compare the growth performance, digestive efficiency and health status of three paternal lines for growing rabbits. The R line was selected by growth rate during the growing period for 37 generations; the RF line was founded by selecting a population of elite R animals (average daily gain>60 g/d); and the RFLP line was founded by backcrossing males from the RF line with females from the LP maternal line. A total of 387 weaned rabbits were used to evaluate growing performance from weaning until 63 d of age in individual cages, in three batches. Additionally, 33 animals were used to determine nutrient digestive efficiency in a digestibility trial. Body weight and feed intake were controlled at weaning (28 d), 46 and 63 d of age. Mortality and morbidity were also monitored daily. During the digestibility trial, feed intake and faeces excretion were controlled daily. Results showed no significant effects of genetic type on body weight, daily feed intake and feed conversion ratio throughout the experiment. However, RF animals had a higher average daily gain from 28 to 46 d of age (+4.4%; P<0.05) compared with R animals, but lower from 46 to 63 d of age (–4.3%; P<0.05). Regarding digestive efficiency, RF and RFLP lines showed slightly higher faecal digestibility for dry matter and gross energy of the diet compared with the R line (+1.3 percentage points; P<0.05). Mortality was higher in animals from R and RF lines compared with RFLP (on av. 25.40 vs. 14.06%; P<0.05). Our results suggest that the RFLP genetic line could be a suitable alternative to the R line, as it shows a similar growth performance but a lower incidence of digestive disorders.This study was funded by the Ministry of Science, Innovation and Universities of the Government of Spain (AGL2017-85162-C2-1-R) and the General Direction of Science and Research of the Generalitat Valenciana (AICO/2012/256). The grantfor Catarina Peixoto Gonçalves is also gratefully acknowledged (GRISOLIAP/2019/149; from the General Direction of Science andResearch of the Generalitat Valenciana).Peixoto-Gonçalves, C.; Martínez-Paredes, E.; Ródenas, L.; Corpa, JM.; Blas, E.; Cambra-López, M.; Pascual, JJ. (2023). Growth performance of three paternal rabbit lines with different potential for growth rate and resilience. World Rabbit Science. 31(4):221-228. https://doi.org/10.4995/wrs.2023.1984122122831

Adjunctive Phosphodiesterase-4 Inhibitor Therapy Improves Antibiotic Response to Pulmonary Tuberculosis in a Rabbit Model

Objectives: Adjunctive host-directed therapy is emerging as a new potential approach to improve the outcome of conventional antimicrobial treatment for tuberculosis (TB).We tested the ability of a phosphodiesterase-4 inhibitor (PDE4i) CC-11050, co-administered with the first-line anti-TB drug isoniazid (INH), to accelerate bacillary killing and reduce chronic inflammation in the lungs of rabbits with experimental Mycobacterium tuberculosis (Mtb) infection. Methods: A rabbit model of pulmonary TB that recapitulates the pathologic manifestations seen in humans was used. Rabbits were infected with virulent Mtb by aerosol exposure and treated for eight weeks with INH with orwithout CC-11050, starting at fourweeks post infection. The effect of CC-11050 treatment on disease severity, pathology, bacillary load, T cell proliferation and global lung transcriptome profiles were analyzed. Results: Significant improvement in bacillary clearance and reduced lung pathology and fibrosis were noted in the rabbits treated for eight weeks with INH + CC-11050, compared to those treated with INH or CC-11050 only. In addition, expression of host genes associated with tissue remodeling, tumor necrosis factor alpha (TNF-α) regulation, macrophage activation and lung inflammation networks was dampened in CC-11050- treated, compared to the untreated rabbits. Conclusions: Adjunctive CC-11050 therapy significantly improves the response of rabbits with experimental pulmonary TB to INH treatment.We propose that CC-11050 may be a promising candidate for host directed therapy of patients with pulmonary TB, reducing the duration and improving clinical outcome of antibiotic treatment

Reproductive performance of rabbit females from three paternal lines with a different potential for growth rate and resilience

[EN] A total of 197 nulliparous rabbits (from three paternal lines) were used to test potential strategies to overcome the consequences on reproduction associated with the selection for high growth rate. The R line was selected for growth rate during the growing period for 37 generations, the RF line was founded through a high selection intensity of elite animals of the R line, and the RFLP line, which was obtained by backcrossing RF animals with the LP line (a long-lived productive maternal line, characterised by high resilience). Body weight, perirenal fat thickness, fertility, daily feed intake, milk yield and blood metabolites of females were controlled from 1st artificial insemination to 3rd parturition. Litter size, litter weight, individual weight and feed ingestion of kits were controlled from birth to weaning. Our results show that RF females were significantly lighter than R and RFLP females throughout the trial (-5.0%; P<0.05). Furthermore, RF animals had a higher fertility rate than RFLP females, at first cycle (+10.5 percentage points; P<0.05). However, RFLP had a higher fertility rate than RF females at second cycle (+21.5 percentage points; P<0.01). On average, RFLP females had higher perirenal fat thickness than R females at parturition (+3.0%; P<0.05) and higher daily feed intake than of R and RF females during gestation and late lactation (+9.7% and +8.7%, respectively; P<0.05). RFLP females produced more milk than R and RF females in the two first lactations (+18.5%; P<0.001). In the first three parturitions, R females delivered fewer kits born alive (-1.7 kits than RF and RFLP; P<0.05). In addition, R females¿ blood had a higher concentration of glutamine and glutamate than RFLP (+24% and +22.7%, respectively; P<0.05). RFLP litters were heavier than both R and RF litters throughout lactation. However, R kits were heavier at birth than RF and RFLP (+7.9 %). Results suggest that the foundation of a paternal line using elite animals could generate females with better early reproductive performance. In addition, backcrossing the RF line with a maternal LP line resulted in a genetic line whose females had a different resource allocation strategy to foster reproduction during the studied period.Financial support statement This study was funded by the Ministry of Science, Innovation and Universities of the Government of Spain (AGL2017-85162-C2-1-R) and the General Direction of Science and Research of the Generalitat Valenciana (AICO/2012/256)Peixoto Gonçalves, CA.; Martinez-Paredes, E.; Ródenas Martínez, L.; Larsen, T.; Corpa, J.; Blas Ferrer, E.; Cambra López, M.... (2023). Reproductive performance of rabbit females from three paternal lines with a different potential for growth rate and resilience. Animal. 17(6):1-10. https://doi.org/10.1016/j.animal.2023.10072911017

Chronic pulmonary cavitary tuberculosis in rabbits: a failed host immune response

The molecular determinants of the immune response to Mycobacterium tuberculosis HN878 infection in a rabbit model of pulmonary cavitary tuberculosis were studied. Aerosol infection of rabbits resulted in a highly differentially expressed global transcriptome in the lungs at 2 weeks, which dropped at 4 weeks and then gradually increased. While IFNγ was progressively upregulated throughout the infection, several other genes in the IFNγ network were not. T-cell activation network genes were gradually upregulated and maximally induced at 12 weeks. Similarly, the IL4 and B-cell activation networks were progressively upregulated, many reaching high levels between 12 and 16 weeks. Delayed peak expression of genes associated with macrophage activation and Th1 type immunity was noted. Although spleen CD4(+) and CD8(+) T cells showed maximal tuberculosis antigen-specific activation by 8 weeks, macrophage activation in lungs, lymph nodes and spleen did not peak until 12 weeks. In the lungs, infecting bacilli grew exponentially up to 4 weeks, followed by a steady-state high bacillary load to 12 weeks that moderately increased during cavitation at 16 weeks. Thus, the outcome of HN878 infection of rabbits was determined early during infection by a suboptimal activation of innate immunity and delayed T-cell activation

Phosphodiesterase-4 Inhibition Alters Gene Expression and Improves Isoniazid – Mediated Clearance of Mycobacterium tuberculosis in Rabbit Lungs

Tuberculosis (TB) treatment is hampered by the long duration of antibiotic therapy required to achieve cure. This indolent response has been partly attributed to the ability of subpopulations of less metabolically active Mycobacterium tuberculosis (Mtb) to withstand killing by current anti-TB drugs. We have used immune modulation with a phosphodiesterase-4 (PDE4) inhibitor, CC-3052, that reduces tumor necrosis factor alpha (TNF-α) production by increasing intracellular cAMP in macrophages, to examine the crosstalk between host and pathogen in rabbits with pulmonary TB during treatment with isoniazid (INH). Based on DNA microarray, changes in host gene expression during CC-3052 treatment of Mtb infected rabbits support a link between PDE4 inhibition and specific down-regulation of the innate immune response. The overall pattern of host gene expression in the lungs of infected rabbits treated with CC-3052, compared to untreated rabbits, was similar to that described in vitro in resting Mtb infected macrophages, suggesting suboptimal macrophage activation. These alterations in host immunity were associated with corresponding down-regulation of a number of Mtb genes that have been associated with a metabolic shift towards dormancy. Moreover, treatment with CC-3052 and INH resulted in reduced expression of those genes associated with the bacterial response to INH. Importantly, CC-3052 treatment of infected rabbits was associated with reduced ability of Mtb to withstand INH killing, shown by improved bacillary clearance, from the lungs of co-treated animals compared to rabbits treated with INH alone. The results of our study suggest that changes in Mtb gene expression, in response to changes in the host immune response, can alter the responsiveness of the bacteria to antimicrobial agents. These findings provide a basis for exploring the potential use of adjunctive immune modulation with PDE4 inhibitors to enhance the efficacy of existing anti-TB treatment

Molecular immunologic correlates of spontaneous latency in a rabbit model of pulmonary tuberculosis

Background: Infection of humans with Mycobacterium tuberculosis (Mtb) results in latent tuberculosis infection (LTBI) in 90-95% of immune competent individuals, with no symptoms of active disease. The World Health Organization estimates that 1.5 billion people have LTBI, which can reactivate in the setting of waning host immunity, posing a threat to global TB control. Various animal models have been used to study the pathogenesis of TB. However, besides nonhuman primates, rabbits are the only animal model that fully recapitulates the pathological features of human TB, including progressive disease with necrosis and cavitation or establishment of spontaneous latency. Results: We defined the molecular immunological correlates of LTBI establishment in a rabbit model of pulmonary infection with Mtb CDC1551. After aerosol infection, exponential bacterial growth was noted in the lungs for 4 weeks, followed by a significant decline by 12 weeks, resulting in the absence of cultivable bacilli by 24 weeks. We used rabbit whole genome microarrays to profile the lung transcriptome during the course of infection. At 2 weeks post-infection, gene networks involved in natural killer (NK) and dendritic cell (DC) activation and macrophage antimicrobial activities were highly upregulated. This was followed by upregulation of gene networks involved in macrophage and T cell activation and autophagy, peaking at 4 to 8 weeks. Concomitantly, host Th1, but not Th2 or inflammatory, immune response genes were significantly upregulated. Thus, the expression kinetics of genes involved in cross-talk between innate and adaptive immunity over the first 8 weeks post-infection were consistent with early efficient control of infection in the lungs. Interestingly, expression of many genes of the host innate and adaptive immune response pathways was downregulated at 12 weeks, suggesting that immune activation did not persist once bacilli began to clear from the infected lungs. Conclusions: Our results suggest that early activation of host innate immunity prior to efficient activation of T cell-mediated adaptive immunity but not inflammation is essential for establishment of LTBI in Mtb CDC1551-infected rabbits. We also show that T cell activation and the host adaptive immune response networks are dampened once bacterial growth is controlled, ultimately resulting in spontaneous LTBI

Early innate immunity determines outcome of Mycobacterium tuberculosis pulmonary infection in rabbits

Background: Pulmonary infection of humans by Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), results in active disease in 5-10% of individuals, while asymptomatic latent Mtb infection (LTBI) is established in the remainder. The host immune responses that determine this differential outcome following Mtb infection are not fully understood. Using a rabbit model of pulmonary TB, we have shown that infection with the Mtb clinical isolate HN878 (a hyper-virulent W-Beijing lineage strain) leads to progressive cavitary disease similar to what is seen in humans with active TB. In contrast, infection with Mtb CDC1551 (a hyper-immunogenic clinical isolate) is efficiently controlled in rabbit lungs, with establishment of LTBI, which can be reactivated upon treatment with immune-suppressive drugs. We hypothesize that the initial interaction of Mtb with the cells of the host response in the lungs determine later outcome of infection. Results: To test this hypothesis, we used our rabbit model of pulmonary TB and infected the animals with Mtb HN878 or CDC1551. At 3 hours, with similar lung bacillary loads, HN878 infection caused greater accumulation of mononuclear and polymorphonuclear leukocytes (PMN) in the lungs, compared to animals infected with CDC1551. Using whole-genome microarray gene expression analysis, we delineated the early transcriptional changes in the lungs of HN878- or CDC1551-infected rabbits at this time and compared them to the differential response at 4 weeks of Mtb-infection. Our gene network and pathway analysis showed that the most significantly differentially expressed genes involved in the host response to HN878, compared to CDC1551, at 3 hours of infection, were components of the inflammatory response and STAT1 activation, recruitment and activation of macrophages, PMN, and fMLP (N-formyl-Methionyl-Leucyl-Phenylalanine)-stimulation. At 4 weeks, the CDC1551 bacillary load was significantly lower and the granulomatous response reduced compared to HN878 infection. Moreover, although inflammation was dampened in both Mtb infections at 4 weeks, the majority of the differentially expressed gene networks were similar to those seen at 3 hours. Conclusions: We propose that differential regulation of the inflammation-associated innate immune response and related gene expression changes seen at 3 hours determine the long term outcome of Mtb infection in rabbit lungs

Association of human TLR1 and TLR6 deficiency with altered immune responses to BCG vaccination in South African infants

The development of effective immunoprophylaxis against tuberculosis (TB) remains a global priority, but is hampered by a partially protective Bacillus Calmette-Guérin (BCG) vaccine and an incomplete understanding of the mechanisms of immunity to Mycobacterium tuberculosis. Although host genetic factors may be a primary reason for BCG's variable and inadequate efficacy, this possibility has not been intensively examined. We hypothesized that Toll-like receptor (TLR) variation is associated with altered in vivo immune responses to BCG. We examined whether functionally defined TLR pathway polymorphisms were associated with T cell cytokine responses in whole blood stimulated ex vivo with BCG 10 weeks after newborn BCG vaccination of South African infants. In the primary analysis, polymorphism TLR6_C745T (P249S) was associated with increased BCG-induced IFN-γ in both discovery (n = 240) and validation (n = 240) cohorts. In secondary analyses of the combined cohort, TLR1_T1805G (I602S) and TLR6_G1083C (synonymous) were associated with increased IFN-γ, TLR6_G1083C and TLR6_C745T were associated with increased IL-2, and TLR1_A1188T was associated with increased IFN-γ and IL-2. For each of these polymorphisms, the hypo-responsive allele, as defined by innate immunity signaling assays, was associated with increased production of TH1-type T cell cytokines (IFN-γ or IL-2). After stimulation with TLR1/6 lipopeptide ligands, PBMCs from TLR1/6-deficient individuals (stratified by TLR1_T1805G and TLR6_C745T hyporesponsive genotypes) secreted lower amounts of IL-6 and IL-10 compared to those with responsive TLR1/6 genotypes. In contrast, no IL-12p70 was secreted by PBMCs or monocytes. These data support a mechanism where TLR1/6 polymorphisms modulate TH1 T-cell polarization through genetic regulation of monocyte IL-10 secretion in the absence of IL-12. These studies provide evidence that functionally defined innate immune gene variants are associated with the development of adaptive immune responses after in vivo vaccination against a bacterial pathogen in humans. These findings could potentially guide novel adjuvant vaccine strategies as well as have implications for IFN-γ-based diagnostic testing for TB

Experimental Evidence for Reduced Rodent Diversity Causing Increased Hantavirus Prevalence

Emerging and re-emerging infectious diseases have become a major global environmental problem with important public health, economic, and political consequences. The etiologic agents of most emerging infectious diseases are zoonotic, and anthropogenic environmental changes that affect wildlife communities are increasingly implicated in disease emergence and spread. Although increased disease incidence has been correlated with biodiversity loss for several zoonoses, experimental tests in these systems are lacking. We manipulated small-mammal biodiversity by removing non-reservoir species in replicated field plots in Panama, where zoonotic hantaviruses are endemic. Both infection prevalence of hantaviruses in wild reservoir (rodent) populations and reservoir population density increased where small-mammal species diversity was reduced. Regardless of other variables that affect the prevalence of directly transmitted infections in natural communities, high biodiversity is important in reducing transmission of zoonotic pathogens among wildlife hosts. Our results have wide applications in both conservation biology and infectious disease management

Effect of Standard Tuberculosis Treatment on Plasma Cytokine Levels in Patients with Active Pulmonary Tuberculosis

CITATION: Riou, C. et al. 2012. Effect of standard tuberculosis treatment on plasma cytokine levels in patients with active pulmonary tuberculosis. PLoS ONE, 7(5): e36886, doi:10.1371/journal.pone.0036886.The original publication is available at http://journals.plos.org/plosoneBackground: Sputum Mycobacterium tuberculosis (Mtb) culture is commonly used to assess response to antibiotic treatment in individuals with pulmonary tuberculosis (TB). Such techniques are constrained by the slow growth rate of Mtb, and more sensitive methods to monitor Mtb clearance are needed. The goal of this study was to evaluate changes in plasma cytokines in patients undergoing treatment for TB as a means of identifying candidate host markers associated with microbiologic response to therapy. Methods: Twenty-four plasma cytokines/chemokines were measured in 42 individuals diagnosed with active pulmonary TB, 52% were HIV co-infected. Individuals, undergoing a 26-week standard TB treatment, were followed longitudinally over 18 months and measurements were associated with HIV status and rates of sputum culture conversion. Results: Plasma concentrations of interferon-inducible protein-10 (IP-10) and vascular endothelial growth factor (VEGF) were significantly reduced upon TB treatment, regardless of HIV status. By the end of treatment, IP-10 concentrations were significantly lower in HIV negative individuals when compared to HIV-positive individuals (p = 0.02). Moreover, in HIV negative patients, plasma VEGF concentrations, measured as early as 2-weeks post TB treatment initiation, positively correlated with the time of sputum conversion (p = 0.0017). No significant changes were observed in other studied immune mediators. Conclusions: These data suggest that VEGF plasma concentration, measured during early TB treatment, could represent a surrogate marker to monitor sputum culture conversion in HIV uninfected individuals.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0036886Publisher's versio