Evaluation of a novel intramuscular prime/intranasal boost vaccination strategy against influenza in the pig model.

Live-attenuated influenza vaccines (LAIV) offer advantages over the commonly used inactivated split influenza vaccines. However, finding the optimal balance between sufficient attenuation and immunogenicity has remained a challenge. We recently developed an alternative LAIV based on the 2009 pandemic H1N1 virus with a truncated NS1 protein and lacking PA-X protein expression (NS1(1-126)-ΔPAX). This virus showed a blunted replication and elicited a strong innate immune response. In the present study, we evaluated the efficacy of this vaccine candidate in the porcine animal model as a pertinent in vivo system. Immunization of pigs via the nasal route with the novel NS1(1-126)-ΔPAX LAIV did not cause disease and elicited a strong mucosal immune response that completely blocked replication of the homologous challenge virus in the respiratory tract. However, we observed prolonged shedding of our vaccine candidate from the upper respiratory tract. To improve LAIV safety, we developed a novel prime/boost vaccination strategy combining primary intramuscular immunization with a haemagglutinin-encoding propagation-defective vesicular stomatitis virus (VSV) replicon, followed by a secondary immunization with the NS1(1-126)-ΔPAX LAIV via the nasal route. This two-step immunization procedure significantly reduced LAIV shedding, increased the production of specific serum IgG, neutralizing antibodies, and Th1 memory cells, and resulted in sterilizing immunity against homologous virus challenge. In conclusion, our novel intramuscular prime/intranasal boost regimen interferes with virus shedding and transmission, a feature that will help combat influenza epidemics and pandemics.

Fitness adaptations of Japanese encephalitis virus in pigs following vector-free serial passaging.

Japanese encephalitis virus (JEV) is a zoonotic mosquito-transmitted Flavivirus circulating in birds and pigs. In humans, JEV can cause severe viral encephalitis with high mortality. Considering that vector-free direct virus transmission was observed in experimentally infected pigs, JEV introduction into an immunologically naïve pig population could result in a series of direct transmissions disrupting the alternating host cycling between vertebrates and mosquitoes. To assess the potential consequences of such a realistic scenario, we passaged JEV ten times in pigs. This resulted in higher in vivo viral replication, increased shedding, and stronger innate immune responses in pigs. Nevertheless, the viral tissue tropism remained similar, and frequency of direct transmission was not enhanced. Next generation sequencing showed single nucleotide deviations in 10% of the genome during passaging. In total, 25 point mutations were selected to reach a frequency of at least 35% in one of the passages. From these, six mutations resulted in amino acid changes located in the precursor of membrane, the envelope, the non-structural 3 and the non-structural 5 proteins. In a competition experiment with two lines of passaging, the mutation M374L in the envelope protein and N275D in the non-structural protein 5 showed a fitness advantage in pigs. Altogether, the interruption of the alternating host cycle of JEV caused a prominent selection of viral quasispecies as well as selection of de novo mutations associated with fitness gains in pigs, albeit without enhancing direct transmission frequency.

Infective endocarditis caused by penicillin-resistant viridans group streptococci: a series of nine cases from a Spanish cohort.

BACKGROUND: Infective endocarditis (IE) caused by viridans and gallolyticus group streptococci (VGS-GGS) resistant to penicillin (PEN-R; minimum inhibitory concentration ≥4 mg/L) is rare but poses therapeutic challenges. OBJECTIVES: To describe the characteristics of patients with IE caused by PEN-R VGS-GGS, focusing on antimicrobial management. METHODS: Retrospective analysis of a prospective cohort of definite IE caused by PEN-R VGS-GGS between 2008 and 2023 in 40 Spanish hospitals. We describe clinical characteristics, management and outcome of the cases, and compare them to IE caused by VGS-GGS with susceptibility or susceptibility with increased exposure to penicillin (PEN-I). RESULTS: We identified nine cases of PEN-R VGS-GGS IE in a cohort of 1563 streptococcal IE (0.58%). All isolates belonged to S. mitis group. Three cases died during hospitalization and no relapse occurred at 3 months of follow-up. Compared to cases with susceptibility or PEN-I, PEN-R showed a higher rate of mitral location (78% versus 51%), surgical indication (67% versus 51%), and in-hospital mortality (33% versus 12%). Most cases (86%) showed resistance to third-generation cephalosporins. The preferred antibiotic regimen was beta-lactam-based: ceftriaxone plus gentamicin, penicillin plus gentamicin, ceftriaxone plus levofloxacin, and ceftaroline plus daptomycin. Two cases received a combination of vancomycin plus gentamicin. Levofloxacin was used in two cases in combination with ceftriaxone or daptomycin. All patients that received cardiac surgery were cured at the end of follow-up. CONCLUSIONS: IE caused by PEN-R VGS-GGS was rare and only affected mitis group streptococci. Antibiotic combination including a beta-lactam seems to be effective in its management.

Structural and Dynamical Properties of Elastin-Like Peptides near Their Lower Critical Solution Temperature.

Elastin-like peptides (ELPs) are artificially derived intrinsically disordered proteins (IDPs) mimicking the hydrophobic repeat unit in the protein elastin. ELPs are characterized by a lower critical solution temperature (LCST) in aqueous media. Here, we investigate the sequence GVG(VPGVG)3 over a wide range of temperatures (below, around, and above the LCST) and peptide concentrations employing all-atom molecular dynamics simulations, where we focus on the role of intra- and interpeptide interactions. We begin by investigating the structural properties of a single peptide that demonstrates a hydrophobic collapse with temperature, albeit moderate, because the sequence length is short. We observe a change in the interaction between two peptides from repulsive to attractive with temperature by evaluating the potential of mean force, indicating an LCST-like behavior. Next, we explore dynamical and structural properties of peptides in multichain systems. We report the formation of dynamical aggregates with coil-like conformation, in which valine central residues play an important role. Moreover, the lifetime of contacts between chains strongly depends on the temperature and can be described by a power-law decay that is consistent with the LCST-like behavior. Finally, the peptide translational and internal motion are slowed by an increase in the peptide concentration and temperature.

Macroscopic analogue to entangled polymers.

The entangled structure of polymeric materials is often described as resembling a bowl of spaghetti, swarms of earthworms, or snakes. These analogies not only illustrate the concept, but form the foundation of polymer physics. However, the similarity between these macroscopic, athermal systems and polymers in terms of topology remains uncertain. To better understand this relationship, we conducted an experiment using X-ray tomography to study the structure of arrays of linear rubber bands. We found that, similar to linear polymers, the average number of entanglements increases linearly with the length of the ribbons. Additionally, we observed that entanglements are less frequent near the surface of the container, where there are also more ends, similar to what has been seen in trapped polymers. These findings provide the first experimental evidence supporting the visualization of polymer structures using macroscopic, athermal analogues, confirming the initial intuitive insights of the pioneers of polymer physics.

Breast abscess due to Nannizziopsis obscura in an immunocompromised renal transplant patient after travel to Nigeria: case report and review.

BACKGROUND: Nannizziopsis is a genus of fungi with several known cases in reptiles of pyogranulomatous infections at cutaneous and musculoskeletal level, of rapid and fatal evolution. There are few cases of this genus described in humans, mainly skin affection but also with visceral abcesses, typically in immunosuppressed patients, with a recent visit to Africa. CASE PRESENTATION: A 45-year-old woman immunosuppressed after renal transplantation and with a recent visit to Nigeria presented with a painless breast abcess, ulceration to the skin and bleeding, and non hematic telorrhea. The mammogram, also completed with an ultrasound scan, showed a polylobulated nodule, BI-RADS 4C. Due to the suspicion of breast cancer, a core needle biopsy was performed and the pathology study showed abundant presence of fungal spores and hyphae. It was identified by genomic amplification of the internal transcription spacer region-2 and a percentage of similarity with sequences of Nannizziopsis obscura from GenBank of 98% was obtained. An empiric treatment with anidulafungin was initiated, and after the surgical resection, it was replaced by isavuconazole, with a total time of treatment of one month. CONCLUSIONS: This is the first case report of a successful treatment of Nannizziopsis obscura with isavuconazole, with the shortest time of treatment published for this fungi. We highlighted the importance of referring difficult to diagnose species to reference centers, as well as achieving the most complete resection in order to shorten the antibiotic therapy.

Application of untargeted volatile profiling in inflammatory bowel disease research.

Inflammatory bowel disease (IBD) diagnosis depends on criteria based on histological, endoscopic, radiological, and clinical results. These studies show drawbacks as being expensive, invasive, and time-consuming. In this work, an untargeted metabolomic strategy based on the monitoring of volatile compounds in serum by headspace gas chromatography-mass spectrometry is proposed as a complementary, fast, and efficient test for IBD patient diagnosis. To develop the method and build a chemometric model that allows the IBD diagnosis, serum samples including IBD patients and healthy volunteers were collected. Analyses were performed by incubating 400 µL of serum for 10 min at 90 °C. For data processing, an untargeted metabolomic strategy was used. A total of 96 features were detected, of which a total of 10 volatile compounds could be identified and confirmed by means of the analysis of real standards. The chemometric treatment consisted of a discriminant analysis of orthogonal partial least squares (OPLS-DA) obtaining a 100% of classification rate, since all the analyzed samples were correctly classified.

Packing structure of semiflexible rings.

Unraveling the packing structure of dense assemblies of semiflexible rings is not only fundamental for the dynamical description of polymer rings, but also key to understand biopackaging, such as observed in circular DNA of viruses or genome folding. Here we use X-ray tomography to study the geometrical and topological features of disordered packings of rubber bands in a cylindrical container. Assemblies of short bands assume a liquid-like disordered structure, with short-range orientational order, and reveal only minor influence of the container. In the case of longer bands, the confinement causes folded configurations and the bands interpenetrate and entangle. Most of the systems are found to display a threading network which percolates the system. Surprisingly, for long bands whose diameter is more than twice the diameter of the container, we found that all bands interpenetrate each other, in a complex fully entangled structure.

Use of polypyrrole ferrite microparticles and liquid chromatography-mass spectrometry for testing natural grass contamination by multiclass mycotoxins.

An analytical methodology based on the combination of dispersive magnetic solid-phase extraction (DMSPE) and liquid chromatography-mass spectrometry (LC-MS) is proposed to explore the occurrence of 13 mycotoxins (aflatoxins B1, G1, B2, and G2; deoxynivalenol; T-2 toxin; ochratoxin A; HT-2 toxin; enniatins A, A1, B, and B2; and beauvericin) and their derivatives in natural grass samples. Magnetic microparticles (Fe3O4) coated with polypyrrole (PPy) polymer were used in DMSPE sample treatment as adsorbent phase, and Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy have been used for its characterization. The experimental parameters influencing the adsorption and desorption steps of DMSPE have been optimized. Method validation has been carried out obtaining limits of quantification between 0.07 and 92 µg kg-1 corresponding to enniatin B or A1 and DON, respectively. A total of 83 natural grass samples from 8 dehesa farms were analysed. Enniatin B was found in all the samples (0.29 to 488 µg kg-1 concentration range) followed by enniatin B1 (92.8% of the samples) with a 0.12-137 µg kg-1 concentration range. Moreover, co-occurrence of mycotoxins was studied and between 2 and 5 mycotoxins appeared simultaneously in 97.6% of the samples. Distribution of the contamination according to natural grass location was also investigated.

Feed corrective lenslets for enhanced beamscan in flat lens antenna systems.

A method for improving beamscan performance of flat lens antenna systems is proposed, wherein small gradient index (GRIN) lenses are included in the feed apertures to correct spillover losses and improve scan collimation. Given a lens system with a flat feed surface, these feed-corrective-lenslets (FCLs) sit in the apertures of offset feed elements and squint the feed pattern toward the center of the lens, reducing spillover radiation and increasing gain at scan. Furthermore, the FCLs shift the effective phase center of the feed to be closer to the Petzval surface, improving scanned collimation and enhancing beam angle. A GRIN lens and FCLs for three offset positions are designed, fabricated and demonstrated in the Ku-band. The FCLs improve the gain of the scanned beam by up to 2 dB out to 50°, reducing the scan loss exponent from 5.0 to 2.5 at 18 GHz.

Comparative pathogenesis of peste des petits ruminants virus strains of difference virulence.

Peste des petits ruminants (PPR) is an acute disease of small ruminants caused by a morbillivirus. Clinical observation of the disease in the field revealed that several species of small ruminants are affected to varying degrees. This difference in disease-related effects could depend either on the host or on the virulence of the virus strain. A previous study highlighted the difference in virulence between two strains of PPRV used to infect Saanen goats. For this breed, PPRV Morocco 2008 strain (MA08) was highly virulent while PPRV Côte d'Ivoire 1989 (IC89) strain induced mild disease. Experimental studies generally based on healthy and young animals do not permit exploration of the natural variability of the host susceptibility to PPRV. Therefore, building on the previous study on Saanen goats, the current study focussed on this breed of goat and used commercially available animals with an unknown history of infection with other pathogens. Results confirmed the previous disease pattern for PPRV IC89 and MA08 strains. Viral RNA detection, macroscopic and histological lesions were stronger for the highly virulent MA08 strain. We show here for the first time that viral RNA can be detected in the tissues of vaccinated animals. Viral RNA was also detected for the first time in serum samples, which is in agreement with the role of circulating immune cells in transporting the virus into host target organs. Thus, this study provides insight into the pathogenesis of strains of different virulence of PPRV and will help to better understand the onset of the disease.

Temperature dependence of thermodynamic, dynamical, and dielectric properties of water models.

We investigate the temperature dependence of thermodynamic (density and isobaric heat capacity), dynamical (self-diffusion coefficient and shear viscosity), and dielectric properties of several water models, such as the commonly employed TIP3P water model, the well-established four-point water model TIP4P-2005, and the recently developed four-point water model TIP4P-D. We focus on the temperature range of interest for the field of computational biophysics and soft matter (280-350 K). The four-point water models lead to a spectacularly improved agreement with experimental data, strongly suggesting that the use of more modern parameterizations should be favored compared to the more traditional TIP3P for modeling temperature-dependent phenomena in biomolecular systems.

Evaluation of the quality of multiple-choice questions according to the students' academic level.

BACKGROUND: One of the most important challenges in medical education is the preparation of multiple-choice questions able to discriminate between students with different academic level. Average questions may be very easy for students with good performance, reducing their discriminant power in this group of students. The aim of this study was to analyze if the discriminative power of multiple-choice questions is different according to the students' academic performance. METHODS: We retrospectively analyzed the difficulty and discrimination indices of 257 multiple-choice questions used for the end of course examination of pathophysiology and analyzed whether the discrimination indices were lower in students with good academic performance (group 1) than in students with moderate/poor academic performance (group 2). We also evaluated whether case-based questions maintained their discriminant power better than factual questions in both groups of students or not. Comparison of the difficulty and discrimination indices between both groups was based on the Wilcoxon test. RESULTS: Difficulty index was significantly higher in group 1 (median: 0.78 versus 0.56; P <  0.001) and discrimination index was significantly higher in group 2 (median: 0.21 versus 0.28; P <  0.001). Factual questions had higher discriminative indices in group 2 than in group 1 (median: 0.28 versus 0.20; P <  0.001), but discriminative indices of case-based questions did not differ significantly between groups (median: 0.30 versus 0.24; P = 0.296). CONCLUSIONS: Multiple-choice question exams have lower discriminative power in the group of students with high scores. The use of clinical vignettes may allow to maintain the discriminative power of multiple-choice questions.

Development of a clinically relevant ovarian cancer model incorporating surgical cytoreduction to evaluate treatment of micro-metastatic disease.

OBJECTIVES: Mouse models of ovarian cancer commonly transfer large numbers of tumor cells into the peritoneal cavity to establish experimental metastatic disease, which may not adequately model early metastatic spread from a primary tumor site. We hypothesized we could develop an ovarian cancer model that predictably represents micro-metastatic disease. METHODS: Murine ID8VEGF ovarian cancer cells were transduced to express enhanced luciferase (eLuc) to enable intravital detection of microscopic disease burden and injected beneath the ovarian bursa of C57Bl/6 mice. At 6 or 10 weeks after orthotopic injection, when mice had detectable metastases, hysterectomy and bilateral salpingo-oophorectomy was performed to remove all macroscopic disease, and survival monitored. Immunohistochemistry and gene expression profiling were performed on primary and metastatic tumors. RESULTS: eLuc-transduced ID8VEGF cells were brighter than cells transduced with standard luciferase, enabling in vivo visualization of microscopic intra-abdominal metastases developing after orthotopic injection. Primary surgical cytoreduction removed the primary tumor mass but left minimal residual disease in all mice. Metastatic sites that developed following orthotopic injection were similar to metastatic human ovarian cancer sites. Gene expression and immune infiltration were similar between primary and metastatic mouse tumors. Surgical cytoreduction prolonged survival compared to no surgery, with earlier cytoreduction more beneficial than delayed, despite micro-metastatic disease in both settings. CONCLUSIONS: Mice with primary ovarian tumors established through orthotopic injection develop progressively fatal metastatic ovarian cancer, and benefit from surgical cytoreduction to remove bulky disease. This model enables the analysis of therapeutic regimens designed to target and potentially eradicate established minimal residual disease.

Eosinophilic fasciitis in a pregnant woman with corticosteroid dependence and good response to infliximab.

Eosinophilic fasciitis (EF) is characterized by symmetrical thickening of subcutaneous muscular fascia, causing skin induration with wrinkles and prominent hair follicles: the classic peau d'orange. Eosinophilia is a characteristic-albeit not universal-finding. We present the case of a 43-year-old pregnant woman diagnosed with EF during pregnancy who had extensive cutaneous involvement and severe functional repercussions, including worsening of lung function and intrauterine growth restriction as a possible complication. Treatment with prednisone was initiated during gestation and it was necessary to increase the dose. After delivery, methotrexate treatment was initiated and the corticosteroid dose progressively decreased, with progressive worsening in the torso and abdomen and secondary dyspnea due to thoracic pressure. Treatment with infliximab was then initiated, with favorable progress, though residual ankle and tarsal joint stiffness and significant muscular atrophy in the limbs continued. The triggering factor of EF was not identified. In a systematic search of the medical literature, three cases of EF in pregnant woman without clear triggers were found. Interestingly, all three cases progressed favorably with steroid treatment. Apart from this case, there are only seven published cases of infliximab use in the literature, all with moderate or complete response. Infliximab could be an option for corticosteroid-dependent EF with no response to other options.

Ultrasound-Guided Hydraulic Release Associated With Corticosteroids in Radial Tunnel Syndrome: Description of Technique and Preliminary Clinical Results.

The aim of this study was to describe a perineural ultrasound-guided infiltration technique for management of radial tunnel syndrome and to report its preliminary results in 54 patients. A mixture of a saline solution, a local anesthetic, and a corticosteroid solution was infiltrated in the perineural region at the arcade of Frohse. Pain was reported in 100% of patients before the procedure versus 1.9% after the procedure. Scratch collapse and Cozen test results were positive in 98.1% and 66.7% of patients before infiltration, respectively, versus 5.6% and 9.2% after infiltration. All variables had statistically significant differences between preprocedure and postprocedure evaluations (P < .01).

Targeting of the Nasal Mucosa by Japanese Encephalitis Virus for Non-Vector-Borne Transmission.

The mosquito-borne Japanese encephalitis virus (JEV) causes severe central nervous system diseases and cycles between Culex mosquitoes and different vertebrates. For JEV and some other flaviviruses, oronasal transmission is described, but the mode of infection is unknown. Using nasal mucosal tissue explants and primary porcine nasal epithelial cells (NEC) at the air-liquid interface (ALI) and macrophages as ex vivo and in vitro models, we determined that the nasal epithelium could represent the route of entry and exit for JEV in pigs. Porcine NEC at the ALI exposed to with JEV resulted in apical and basolateral virus shedding and release of monocyte recruiting chemokines, indicating infection and replication in macrophages. Moreover, macrophages stimulated by alarmins, including interleukin-25, interleukin-33, and thymic stromal lymphopoietin, were more permissive to the JEV infection. Altogether, our data are important to understand the mechanism of non-vector-borne direct transmission of Japanese encephalitis virus in pigs.IMPORTANCE JEV, a main cause of severe viral encephalitis in humans, has a complex ecology composed of a mosquito-waterbird cycle and a cycle involving pigs, which amplifies virus transmission to mosquitoes, leading to increased human cases. JEV can be transmitted between pigs by contact in the absence of arthropod vectors. Moreover, virus or viral RNA is found in oronasal secretions and the nasal epithelium. Using nasal mucosa tissue explants and three-dimensional porcine nasal epithelial cells cultures and macrophages as ex vivo and in vitro models, we determined that the nasal epithelium could be a route of entry as well as exit for the virus. Infection of nasal epithelial cells resulted in apical and basolateral virus shedding and release of monocyte recruiting chemokines and therefore infection and replication in macrophages, which is favored by epithelial-cell-derived cytokines. The results are relevant to understand the mechanism of non-vector-borne direct transmission of JEV.

A CD200R-CD28 fusion protein appropriates an inhibitory signal to enhance T-cell function and therapy of murine leukemia.

Acute myeloid leukemia (AML), the most common adult acute leukemia in the United States, has the poorest survival rate, with 26% of patients surviving 5 years. Adoptive immunotherapy with T cells genetically modified to recognize tumors is a promising and evolving treatment option. However, antitumor activity, particularly in the context of progressive leukemia, can be dampened both by limited costimulation and triggering of immunoregulatory checkpoints that attenuate T-cell responses. Expression of CD200 (OX2), a negative regulator of T-cell function that binds CD200 receptor (CD200R), is commonly increased in leukemia and other malignancies and is associated with poor prognosis in leukemia patients. To appropriate and redirect the inhibitory effects of CD200R signaling on transferred CD8+ T cells, we engineered CD200R immunomodulatory fusion proteins (IFPs) with the cytoplasmic tail replaced by the signaling domain of the costimulatory receptor, CD28. An analysis of a panel of CD200R-CD28 IFP constructs revealed that the most effective costimulation was achieved in IFPs containing a dimerizing motif and a predicted tumor-T-cell distance that facilitates localization to the immunological synapse. T cells transduced with the optimized CD200R-CD28 IFPs exhibited enhanced proliferation and effector function in response to CD200+ leukemic cells in vitro. In adoptive therapy of disseminated leukemia, CD200R-CD28-transduced leukemia-specific CD8 T cells eradicated otherwise lethal disease more efficiently than wild-type cells and bypassed the requirement for interleukin-2 administration to sustain in vivo activity. The transduction of human primary T cells with the equivalent human IFPs increased proliferation and cytokine production in response to CD200+ leukemia cells, supporting clinical translation. This trial was registered at www.clinicaltrials.gov as #NCT01640301.

Efficacy of three innovative bacterin vaccines against experimental infection with Mycoplasma hyopneumoniae.

New vaccine formulations that include novel strains of Mycoplasma hyopneumoniae and innovative adjuvants designed to induce cellular immunity could improve vaccine efficacy against this pathogen. The aim of this experimental study was to assess the efficacy of three experimental bacterin formulations based on M. hyopneumoniae field strain F7.2C which were able to induce cellular immunity. The formulations included a cationic liposome formulation with the Mincle receptor ligand trehalose 6,6-dibehenate (Lipo_DDA:TDB), a squalene-in-water emulsion with Toll-like receptor (TLR) ligands targeting TLR1/2, TLR7/8 and TLR9 (SWE_TLR), and a poly(lactic-co-glycolic acid) micro-particle formulation with the same TLR ligands (PLGA_TLR). Four groups of 12 M. hyopneumoniae-free piglets were primo- (day (D) 0; 39 days of age) and booster vaccinated (D14) intramuscularly with either one of the three experimental bacterin formulations or PBS. The pigs were endotracheally inoculated with a highly and low virulent M. hyopneumoniae strain on D28 and D29, respectively, and euthanized on D56. The main efficacy parameters were: respiratory disease score (RDS; daily), macroscopic lung lesion score (D56) and log copies M. hyopneumoniae DNA determined with qPCR on bronchoalveolar lavage (BAL) fluid (D42, D56). All formulations were able to reduce clinical symptoms, lung lesions and the M. hyopneumoniae DNA load in the lung, with formulation SWE_TLR being the most effective (RDSD28-D56 -61.90%, macroscopic lung lesions -88.38%, M. hyopneumoniae DNA load in BAL fluid (D42) -67.28%). Further experiments raised under field conditions are needed to confirm these results and to assess the effect of the vaccines on performance parameters.

Isolated posterior cruciate ligament aplasia: a case report.

Congenital absence of the cruciate ligaments is a very rare condition, with most reported cases being related to the anterior cruciate ligament (ACL). Posterior cruciate ligament (PCL) congenital abnormalities have been described as almost always being associated with other anomalies. We present a case of a patient with lateral knee pain and subjective instability sensation after a low-energy trauma secondary to a lateral meniscus tear, with absence of the PCL on MRI examination and thickened meniscofemoral ligaments, with anterior and superior insertion at the femur, in the footprint of PCL. The patient had a menisci repair, without PCL reconstruction. At the 6-month follow-up, the patient did not report any instability symptoms during his daily work and sports activities. There are therapeutic implications in distinguishing a chronic PCL tear from an aplasia, so it is important to detect some signs in imaging that may guide to differentiate them, as there could be differences in the course and thickness of meniscofemoral ligaments, besides the absence of the entire PCL. To our knowledge, this is the first case of PCL agenesis with arthroscopic correlation.