Histological Changes in the Kidneys and Heart in Experimental Acanthamoebiasis in Immunocompetent and Immunosuppressed Hosts

The course of Acanthamoeba spp. infection depends on the age and immune status of the host, and the virulence of the Acanthamoeba spp. strain. Some strains of free-living amoebae exhibit organ specificity, during the course of infection, while others may cause changes in many organs or completely lose pathogenicity. The aim of the current study was to investigate the pathological properties of Acanthamoeba spp. isolated from a patient with acute myeloid leukemia and atypical pneumonia (AM22). Moreover, the objective was to investigate the histopathological changes in the kidneys and heart of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. Amoebae were re-isolated from both the kidneys and hearts of the inoculated mice, although no cysts or trophozoites of the amoebae were detected in microscopic slides of the fragments of these organs. Acanthamoeba spp. induced changes in the kidney and heart weight of infected mice. In immunocompetent and immunosuppressed Acanthamoeba spp. infected mice, we found some histopathological changes, including areas with less acidic cytoplasm and a relaxation of muscle fibers. In further studies, it is important to analyze changes in gene and protein expressions in the heart and kidneys of hosts with disseminated acanthamoebiasis to better understand the course of infection in these organs, because the results of histological analysis varied depending on the immune status and duration of infection.

Evaluation of multi-assay algorithms for identifying individuals with recent HIV infection: HPTN 071 (PopART)

Background Assays and multi-assay algorithms (MAAs) have been developed for population-level cross-sectional HIV incidence estimation. These algorithms use a combination of serologic and/or non-serologic biomarkers to assess the duration of infection. We evaluated the performance of four MAAs for individual-level recency assessments. Methods Samples were obtained from 220 seroconverters (infected <1 year) and 4,396 non-seroconverters (infected >1 year) enrolled in an HIV prevention trial (HPTN 071 [PopART]); 28.6% of the seroconverters and 73.4% of the non-seroconverters had HIV viral loads ≤400 copies/mL. Samples were tested with two laboratory-based assays (LAg-Avidity, JHU BioRad-Avidity) and a point-of-care assay (rapid LAg). The four MAAs included different combinations of these assays and HIV viral load. Seroconverters on antiretroviral treatment (ART) were identified using a qualitative multi-drug assay. Results The MAAs identified between 54 and 100 (25% to 46%) of the seroconverters as recently-infected. The false recent rate of the MAAs for infections >2 years duration ranged from 0.2%-1.3%. The MAAs classified different overlapping groups of individuals as recent vs. non-recent. Only 32 (15%) of the 220 seroconverters were classified as recent by all four MAAs. Viral suppression impacted the performance of the two LAg-based assays. LAg-Avidity assay values were also lower for seroconverters who were virally suppressed on ART compared to those with natural viral suppression. Conclusions The four MAAs evaluated varied in sensitivity and specificity for identifying persons infected <1 year as recently infected and classified different groups of seroconverters as recently infected. Sensitivity was low for all four MAAs. These performance issues should be considered if these methods are used for individual-level recency assessments.

Spectrum of High Resolution Computed tomography chest findings in PCR positive COVID-19 patients according to duration of infection and CT severity score assessment

Objective: To evaluate the spectrum of HRCT findings of COVID-19 in RT-PCR positive patients according to duration of infection and severity of disease. Methods: This retrospective study was conducted at Radiology department of Lahore General Hospital, Lahore from May to July 2020. Total 40 COVID-19 patients were reviewed for clinical features, HRCT chest findings based on time from symptom onset and CT conduction. Chi-square and fissure exact test were used for measuring association with severity of COVID-19, p value ≤0.05 was reported significant. Mean CT scores were calculated. ROC curve analysis showed threshold values of CT-SS for severe disease. Results: Of total 40 patients with age ranged from 22-83 years, 22(55%) were males and 18(45%) females. The hallmark of COVID-19 was combined GGO and consolidation, GGO alone and consolidation alone in bilateral, sub pleural and posterior distribution. Early stage had normal CT or GGO alone, intermediate and late stage had both GGO and consolidation. Septal lines/bands and crazy paving pattern were prevalent in late stage. Clinically, 24 (60%) were in severe group and 16(40%) in mild group. Severity of COVID-19 was associated with GGO alone (p=0.05), GGO and consolidation (p=0.01), crazy paving (p=0.01) and lung scores (p≤0.05). The threshold values of CT-SS for identifying severe disease by two radiologists were 18.50 and 20.50. Conclusion: HRCT manifestations along with CT-SS aids in predicting disease severity. Staging according to duration of infection is effective in understanding variation in pattern of chest findings in coronavirus disease. doi: https://doi.org/10.12669/pjms.38.1.4204 How to cite this:Irshad N, Hanif N. Spectrum of High Resolution Computed tomography chest findings in PCR positive COVID-19 patients according to duration of infection and CT severity score assessment. Pak J Med Sci. 2022;38(1):---------. doi: https://doi.org/10.12669/pjms.38.1.4204 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Lower probability and shorter duration of infections after Covid-19 vaccine correlate with anti-SARS-CoV-2 circulating IgGs

The correlation between immune responses and protection from SARS-CoV-2 infections and its duration remains unclear. We performed a sanitary surveillance at the European Institute of Oncology (IEO) in Milan over a 27 months period. Pre-vaccination, in 1493 participants, we scored 266 infections (17.8%) and 8 possible reinfections (3%). Post-vaccination, we identified 30 infections in 2029 vaccinated individuals (1.5%). We report that the probability of infection post-vaccination is i) significantly lower compared to natural infection, ii) associated with a significantly shorter median duration of infection than that of first infection and reinfection, iii) anticorrelated with circulating antibody levels.

Characterizing the Relationship Between Neutralization Sensitivity and env Gene Diversity During ART Suppression

Although antiretroviral therapy (ART) successfully suppresses HIV-1 replication, ART-treated individuals must maintain therapy to avoid rebound from an integrated viral reservoir. Strategies to limit or clear this reservoir are urgently needed. Individuals infected for longer periods prior to ART appear to harbor more genetically diverse virus, but the roles of duration of infection and viral diversity in the humoral immune response remain to be studied. We aim to clarify a role, if any, for autologous and heterologous antibodies in multi-pronged approaches to clearing infection. To that end, we have characterized the breadths and potencies of antibody responses in individuals with varying durations of infection and HIV-1 envelope (env) gene diversity as well as the sensitivity of their inducible virus reservoir to broadly neutralizing antibodies (bNAbs). Plasma was collected from 8 well-characterized HIV-1+ males on ART with varied durations of active infection. HIV envs from reservoir-derived outgrowth viruses were amplified and single genome sequenced in order to measure genetic diversity in each participant. IgG from plasma was analyzed for binding titers against gp41 and gp120 proteins, and for neutralizing titers against a global HIV-1 reference panel as well as autologous outgrowth viruses. The sensitivity to bNAbs of these same autologous viruses was measured. Overall, we observed that greater env diversity was associated with higher neutralizing titers against the global panel and also increased resistance to certain bNAbs. Despite the presence of robust anti-HIV-1 antibody titers, we did not observe potent neutralization against autologous viruses. In fact, 3 of 8 participants harbored viruses that were completely resistant to the highest tested concentration of autologous IgG. That this lack of neutralization was observed regardless of ART duration or viral diversity suggests that the inducible reservoir harbors ‘escaped’ viruses (that co-evolved with autologous antibody responses), rather than proviruses archived from earlier in infection. Finally, we observed that viruses resistant to autologous neutralization remained sensitive to bNAbs, especially CD4bs and MPER bNAbs. Overall, our data suggest that the inducible reservoir is relatively resistant to autologous antibodies and that individuals with limited virus variation in the env gene, such as those who start ART early in infection, are more likely to be sensitive to bNAb treatment.

IMPLEMENTATION OF MICROELIMINATION STRATEGY IN ERADICATION OF CHRONIC HEPATITIS C INFECTION IN PATIENTS WITH HEMOPHILIA IN THE NORTHERN REGION OF SERBIA

Background: Treating HCV in people with hemophilia not only prevents the development of ESLD and HCC, but it also greatly increases the quality of life for people living with hemophilia. There are many obstacles in reaching the WHO goal of globally eradicating HCV by the year 2030., mainly its scale, complexity and implementation. That is why many countries have implemented a micro-elimination strategy: a pragmatic elimination approach in populations with the most efficacy. The aim of this publication is to present the morbidity and mortality rates, the clinical course and treatment outcomes of chronic HCV infection in PWH, as well as to show an example of a successfully conducted HCV micro-elimination strategy among people with hemophilia in the Province of Vojvodina. Methods: A retrospective, single-center study, performed using medical documentation of all registered PWH in the Clinical center of Vojvodina from 1994. until 2020. It included 74 hemophilia patients, out of which 32 were patients with hemophilia and chronic HCV infection. Results: The mean age of HCV positive PWH was 42.3 years, with the duration of infection of 30-35 years. Co-infection with HIV was observed in 6.25% of cases. Furthermore, 18.75% of patients had spontaneous HCV elimination and 75% patients were treated with antiviral protocols. Cirrhosis developed in 21.87% with an incidence rate of 0.6 per 100 patient-years. After treatment with Pegylated IFN and ribavirin (RBV), 58.3% achieved SVR. Side effects of IFN-based therapy regiment were recorded in 20.8% of treated PWH. In 37.5% PWH, DAA protocols were administered, and these patients achieved SVR. HCV positive PWH have a statistically higher mortality rate than non-infected people with hemophilia. Among the HCV positive PWH, hemophilia-related deaths were 6.25%, and HCV-related deaths were 9.37%. Currently, in the Registry of PWH in Vojvodina, there are no patients with active HCV infection. Conclusion: The micro-elimination strategy in subpopulation of PWH was successfully implemented in the Province of Vojvodina in close collaborations of hematologist and infectious diseases specialist.

Establishment and validation of a guinea pig model for human congenital toxoplasmosis

Background Toxoplasma gondii is an obligate intracellular parasite with a worldwide distribution. Congenital infection in humans and animals may lead to severe symptoms in the offspring, especially in the brain. A suitable animal model for human congenital toxoplasmosis is currently lacking. The aim of this study is to establish and validate the guinea pig as a model for human congenital toxoplasmosis by investigating the impact of the T. gondii infection dose, the duration of infection and the gestational stage at infection on the seroconversion, survival rate of dams, fate of the offspring, T. gondii DNA loads in various offspring tissues and organs and the integrity of the offspring brain. Methods Pregnant guinea pigs were infected with three different doses (10, 100, 500 oocysts) of T. gondii strain ME49 at three different time points during gestation (15, 30, 48 days post-conception). Serum of dams was tested for the presence of T. gondii antibodies using immunoblotting. T. gondii DNA levels in the dam and offspring were determined by qPCR. Offspring brains were examined histologically. Results We found the survival rate of dams and fate of the offspring to be highly dependent on the T. gondii infection dose with an inoculation of 500 oocysts ending lethally for all respective offspring. Moreover, both parameters differ depending on the gestational stage at infection with infection in the first and third trimester of gestation resulting in a high offspring mortality rate. The duration of infection was found to substantially impact the seroconversion rate of dams with the probability of seroconversion exceeding 50% after day 20 post-infection. Furthermore, the infection duration of dams influenced the T. gondii DNA loads in the offspring and the integrity of offspring brain. Highest DNA levels were found in the offspring brain of dams infected for ≥ 34 days. Conclusion This study contributes to establishing the guinea pig as a suitable model for human congenital toxoplasmosis and thus lays the foundation for using the guinea pig as a suitable animal model to study scientific questions of high topicality and clinical significance, which address the pathogenesis, diagnosis, therapy and prognosis of congenital toxoplasmosis. Graphical abstract

Comparing antiviral strategies against COVID-19 via multiscale within-host modelling

Within-host models of COVID-19 infection dynamics enable the merits of different forms of antiviral therapy to be assessed in individual patients. A stochastic agent-based model of COVID-19 intracellular dynamics is introduced here, that incorporates essential steps of the viral life cycle targeted by treatment options. Integration of model predictions with an intercellular ODE model of within-host infection dynamics, fitted to patient data, generates a generic profile of disease progression in patients that have recovered in the absence of treatment. This is contrasted with the profiles obtained after variation of model parameters pertinent to the immune response, such as effector cell and antibody proliferation rates, mimicking disease progression in immunocompromised patients. These profiles are then compared with disease progression in the presence of antiviral and convalescent plasma therapy against COVID-19 infections. The model reveals that using both therapies in combination can be very effective in reducing the length of infection, but these synergistic effects decline with a delayed treatment start. Conversely, early treatment with either therapy alone can actually increase the duration of infection, with infectious virions still present after the decline of other markers of infection. This suggests that usage of these treatments should remain carefully controlled in a clinical environment.

Parasite immune evasion and manipulation of host phenotype

All parasites manipulate their hosts by interference with immune defences and host behaviour. Passive evasion, for example, is by molecular mimicry or by changing surfaces. Active interference involves production of molecules that block or modify host immune defence regulation or affect metabolism and neuronal systems. All steps of the immune defence cascades are attacked by parasites, including the microbiota. Manipulation can increase the duration of infection or transmission success. The latter is particularly prominent in intermediate hosts that need to be consumed by a final host. Host fecundity reduction and gigantism provide extra resources for the parasite. Theory can predict what manipulation should be best; conflicts arise among co-infecting parasites.

Citrus photosynthesis and morphology acclimate to phloem-affecting huanglongbing disease at the leaf and shoot levels

Huanglongbing (HLB) is a phloem-affecting disease of citrus that reduces growth and has impacted citrus production in most global production regions. HLB is caused by a phloem-limited bacterium (Candidatus Liberibacter asiaticus; CLas). By inhibiting phloem function, HLB stunts sink growth, including reducing production of new shoots and leaves, and induces hyperaccumulation of foliar starch. Despite evidence that HLB induces feedback inhibition of photosynthesis by reducing foliar carbohydrate export, its effects on net CO2 assimilation (Anet) have not been reported. In this work we assessed the relationship of bacterial distribution within the foliage, foliar starch accumulation, and Anet. Because HLB impacts canopy morphology, we developed a chamber to measure whole shoot Anet, and tested the effects of HLB at both leaf and shoot levels. Starch accumulation was correlated with bacterial population, and starch was negatively correlated with Anet at the leaf but not at the shoot level. Starch increased between the uninfected group and the shortest duration of infection, then decreased progressively with increasing length of infection. HLB infection reduced Anet at the leaf level, but increased it at the whole shoot level. We attribute this enhancement of whole shoot Anet to the increased contribution of stem photosynthesis due to the altered shoot morphology induced by the disease. Despite the increased photosynthetic efficiency, total carbon fixation per shoot decreased because shoot size and leaf area were reduced. Overall, our results indicate a localized relationship of CLas distribution with negative impacts on foliar carbohydrate export and photosynthesis. Additionally, starch accumulation and Anet acclimate over time at the shoot level to the localized impacts of the disease. Stems contribute important proportions of whole shoot Anet, and these contributions are likely increased by the morphological acclimation induced by HLB. This study highlights the importance of temporal and spatial scale in assessing photosynthesis.