[Antiviral drugs : Potent agents, promising therapies for COVID‑19 and therapeutic limitations]

Antiviral drugs inhibit viral replication by interaction with specific elements of the viral replication cycle. Directly acting antiviral agents have revolutionized the therapeutic options for chronic infections with human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). Pharmacological developments constantly improve therapeutic and prophylactic options for diseases caused by herpes viruses, which is of particular relevance for immunocompromised patients. While infections with persistent viruses, such as HIV, HBV or herpes viruses principally so far cannot be cured, complete elimination of viruses that cause acute infections is possible; however, acute infections, such as influenza or coronavirus disease 2019 (COVID-19) offer only a small therapeutic window for antiviral strategies due to their pathophysiological dynamics. The optimal time point for antiviral agents is immediately after exposure to the virus, which frequently limits its application in practice. An effective pre-exposure or postexposure prophylaxis has been established for infections with HIV and influenza A/B and also gains relevance for infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Chronic Infections in Mammals Due to Microsporidia

Microsporidia are pathogenic organism related to fungi. They cause infections in a wide variety of mammals as well as in avian, amphibian, and reptilian hosts. Many microsporidia species play an important role in the development of serious diseases that have significant implications in human and veterinary medicine. While microsporidia were originally considered to be opportunistic pathogens in humans, it is now understood that infections also occur in immune competent humans. Encephalitozoon cuniculi, Encephalitozoon intestinalis, and Enterocytozoon bieneusi are primarily mammalian pathogens. However, many other species of microsporidia that have some other primary host that is not a mammal have been reported to cause sporadic mammalian infections. Experimental models and observations in natural infections have demonstrated that microsporidia can cause a latent infection in mammalian hosts. This chapter reviews the published studies on mammalian microsporidiosis and the data on chronic infections due to these enigmatic pathogens.

[Case of diagnosis and surgical treatment of intracranial cholesteatoma]

The article provides a brief overview of the epidemiology of congenital and acquired intracranial cholesteatoma, the theory of its pathogenesis, classification, and clinical features. The most common localization of congenital and acquired intracranial cholesteatoma is described and various surgical approaches are presented that allow total removal of the formation. A clinical case of diagnosis and surgical treatment of acquired intracranial cholesteatoma caused by chronic suppurative otitis media is presented. A clinical example indicates the possibility of a long asymptomatic course of acquired intracranial cholesteatoma. The use of a combined (extradural subtemporal and transmastoid) surgical approach made it possible to completely remove the acquired cholesteatoma of the temporal lobe of the brain in a patient with chronic suppurative otitis media.

[The effect of red blood cell folate on the prognosis of high-risk human papillomavirus infection: a community-based cohort study]

Objective: To investigate the effect of red blood cell folate on the prognosis of high-risk human papillomavirus (HR-HPV) infection. Methods: A total of 564 participants with low-grade cervical intraepithelial neoplasias (CINⅠ) were selected from the community-based married women cohort established in 2014. The general baseline information and factors related to HPV infection were collected. Meanwhile, HPV genotyping and levels of folate were measured. The subjects were divided into different levels of exposure group according to the folate levels and followed up for 24 months to observe the changes of HR-HPV infection status. There were four changes, including persistent infection, infection turned negative, from negative to positive and constant negative by comparing HR-HPV infection status at baseline and follow-up to 24 months. Results: 483 participators completed 24 months of follow-up observation, with a follow-up rate of 85.64% (483/564). The rates of persistent infection, infection turned negative, from negative to positive, and the constant negative were 52.45% (75/143), 47.55% (68/143), 19.71% (67/340), 80.29% (273/340), respectively. Our results demonstrated that the risk of persistent infection (aRR=2.50, 95%CI: 1.55-4.02) and from negative to positive (aRR=4.55, 95%CI: 2.52-8.23) in the low level of folate were significantly higher than that in the high level of folate, especially the risk of homotype persistent infection (aRR=2.72, 95%CI: 1.51-4.90). The risk of persistent infection (trend χ²=20.62, P<0.001), from negative to positive (trend χ²=31.76, P<0.001), persistent homotypic infection (trend χ²=20.09, P<0.001) increased with the decrease of red blood cell folate level. On the contrary, no similar results were found in persistent heterotypic infection. Conclusions: A low level of red blood cell folate could increase the risk of HR-HPV persistent infection and from negative to positive. In women with HR-HPV infection, the risk of persistent homotypic infection is higher.

Antibiotic therapy for chronic infection with <I>Burkholderia cepacia</I> complex in people with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) a life-limiting inherited disease affecting a number of organs, but classically associated with chronic lung infection and progressive loss of lung function. Chronic infection by Burkholderia cepacia complex (BCC) is associated with increased morbidity and mortality and therefore represents a significant challenge to clinicians treating people with CF. This review examines the current evidence for long-term antibiotic therapy in people with CF and chronic BCC infection.

OBJECTIVES

The objective of this review is to assess the effects of long-term oral and inhaled antibiotic therapy targeted against chronic BCC lung infections in people with CF. The primary objective is to assess the efficacy of treatments in terms of improvements in lung function and reductions in exacerbation rate. Secondary objectives include quantifying adverse events, mortality and changes in quality of life associated with treatment.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched online trial registries and the reference lists of relevant articles and reviews. Date of last search: 12 April 2021.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of long-term antibiotic therapy in people with CF and chronic BCC infection.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed risk of bias and assessed the quality of the evidence using GRADE.

MAIN RESULTS

We included one RCT (100 participants) which lasted 52 weeks comparing continuous inhaled aztreonam lysine (AZLI) and placebo in a double-blind RCT for 24 weeks, followed by a 24-week open-label extension and a four-week follow-up period. The average participant age was 26.3 years, 61% were male and average lung function was 56.5% predicted. Treatment with AZLI for 24 weeks was not associated with improvement in forced expiratory volume in one second (FEV₁), mean difference 0.91% (95% confidence interval (CI) -3.15 to 4.97) (moderate-quality evidence). The median time to the next exacerbation was 75 days in the AZLI group compared to 51 days in the placebo group, but the difference was not significant (P = 0.27) (moderate-quality evidence). Similarly, the number of participants hospitalised for respiratory exacerbations showed no difference between groups, risk ratio (RR) 0.88 (95% CI 0.53 to 1.45) (moderate-quality evidence). Overall adverse events were similar between groups, RR 1.08 (95% CI 0.98 to 1.19) (moderate-quality evidence). There were no significant differences between treatment groups in relation to mortality (moderate-quality evidence), quality of life or sputum density. In relation to methodological quality, the overall risk of bias in the study was assessed to be unclear to low risk.

AUTHORS' CONCLUSIONS

We found insufficient evidence from the literature to determine an effective strategy for antibiotic therapy for treating chronic BCC infection.

The stochastic bifurcation analysis and stochastic delayed optimal control for epidemic model with general incidence function

In the history of the world, contagious diseases have been proved to pose serious threats to humanity that needs uttermost research in the field and its prompt implementations. With this motive, an attempt has been made to investigate the spread of such contagion by using a delayed stochastic epidemic model with general incidence rate, time-delay transmission, and the concept of cross immunity. It is proved that the system is mathematically and biologically well-posed by showing that there exist a positive and bounded global solution of the model. Necessary conditions are derived, which guarantees the permanence as well as extinction of the disease. The model is further investigated for the existence of an ergodic stationary distribution and established sufficient conditions. The non-zero periodic solution of the stochastic model is analyzed quantitatively. The analysis of optimality and time delay is used, and a proper strategy was presented for prevention of the disease. A scheme for the numerical simulations is developed and implemented in MATLAB, which reflects the long term behavior of the model. Simulation suggests that the noises play a vital role in controlling the spread of an epidemic following the proposed flow, and the case of disease extinction is directly proportional to the magnitude of the white noises. Since time delay reflects the dynamics of recurring epidemics, therefore, it is believed that this study will provide a robust basis for studying the behavior and mechanism of chronic infections.

Liver Disease: Hepatitis C

Approximately 4.1 million individuals in the United States have a history of hepatitis C virus (HCV) exposure, including 2.5 million with chronic infection. Screening guidelines recommend one-time, routine, opt out HCV screening for all individuals 18 years or older. Risk-based testing is recommended for specific individuals. Although many patients with chronic hepatitis C may progress to cirrhosis, end-stage liver disease, and hepatocellular carcinoma, early treatment can prevent development of these sequelae. Management of hepatitis C has simplified significantly, and primary care physicians now can monitor and provide treatment for most patients. Adults with chronic hepatitis C who do not have cirrhosis and have not received hepatitis C treatment previously are eligible for primary care-based treatment. These patients should undergo a comprehensive pretreatment evaluation to guide treatment planning. Patients typically are treated with one of two pangenotypic regimens: glecaprevir-pibrentasvir for 8 weeks or sofosbuvir-velpatasvir for 12 weeks. Virologic cure, defined as sustained virologic response (SVR) at 12 weeks after treatment completion, should be confirmed by an undetectable quantitative HCV RNA via polymerase chain reaction test performed 12 weeks or later after treatment completion. Management results in rates of virologic cure of greater than 95% across genotypes. Patients who do not achieve SVR at 12 weeks should be referred to a subspecialist experienced in management of treatment failure.

Plantar fascial fibromatosis and herpes zoster

Purpose

Infection, chronic pain and depression are considered risk factors for herpes zoster (HZ). However, the correlation between plantar fascial fibromatosis (PFF) and HZ remains unknown. This study investigated HZ risk in patients with PFF.

Methods

Data was extracted from the Longitudinal Health Insurance Database 2000, which is a subsample of the Taiwan National Health Insurance (NHI) Research Database and contains 1 million NHI beneficiaries. Between 2000 and 2012, patients diagnosed as having PFF were included in the case cohort. Every case was age and sex-matched with individuals without PFF through 1:4 frequency matching (control cohort). The end of the follow-up was defined as December 31, 2013, the date of HZ diagnosis, death, emigration, or withdrawal from the NHI program.

Results

In total, 4,729 patients were diagnosed as having PFF and were matched with 18,916 individuals without PFF. Patients with PFF were 1.23 times more likely to develop HZ than were those without PFF. Among those aged ≥65 years, patients with PFF had a higher HZ risk than did those without PFF (adjusted hazard ratio [aHR] = 1.48). Men with PFF had a significantly higher risk of HZ than did men without PFF (aHR = 1.44).

Conclusion

Patients with PFF, particularly older and male patients, having a high HZ risk and may thus be vaccinated for HZ.

An immunosuppressed woman in her seventies with night sweats and weight loss

BACKGROUND

Candidatus Neoehrlichia mikurensis is an emerging tick-borne pathogen with widespread distribution in Ixodes ricinus ticks in Europe and Asia. It has been found to cause chronic infections, particularly in immunosuppressed individuals. Common symptoms include relapsing fever, night sweats and thromboembolic episodes, likely due to endovascular infection.

CASE PRESENTATION

A patient in her seventies developed persistent night sweats and moderate weight loss that persisted for four months prior to evaluation. There was no history of fever or organ-specific symptoms. Prior diseases included a ten-year history of rheumatoid arthritis treated with rituximab. Initial workup revealed moderately increased acute phase reactants, but no evidence of malignant disease or endocrine abnormalities. Night sweats persisted, and after eight months moderate splenic enlargement was observed. PCR revealed presence of Candidatus Neoehrlichia mikurensis DNA, and symptoms resolved promptly after initiation of oral doxycycline treatment.

INTERPRETATION

Infection with anaplasmataceae such as Candidatus Neoehrlichia mikurensis can present with non-specific constitutive symptoms. In this case, persistent night sweats and moderate weight loss were the only manifestations over an eight-month period. Diagnosis is readily established by PCR analysis of whole blood, but a high degree of suspicion and careful assessment of potential exposure is required for timely diagnosis.

In vitro assembly and evaluation of Nora virus VLPs

Nora virus is a RNA picorna-like virus that produces a persistent infection in Drosophila melanogaster. The genome is approximately 12,300 bases and is divided into four open reading frames (ORFs). Structurally, there are four important viral proteins: VP3, VP4A, VP4B, and VP4C. Three proteins (VP4A, VP4B, and VP4C) form the virion's capsid and are encoded in ORF 4, which produces a polyprotein that is post-translationally cleaved. The fourth protein (VP3) is encoded in ORF 3 and it is hypothesized to play a role in virion stability. The genes for these proteins were individually cloned into Escherichia coli, expressed, and the proteins were purified. Virus-like particles (VLPs) were assembled in vitro by mixing the proteins together in different combinations and measured via electron microscopy. Assemblies that contained VP4A and/or VP3 created VLPs with similar sizes to purified empty Nora virus capsids, potentially indicating that VP4A and/or VP3 are vital for Nora virus capsid structure, assembly, and/or stability. Not only does this study provide insight into the role of Nora virus proteins, but it may also lead to a deeper understanding of how Nora virus or other picorna-like viruses undergo assembly.  Keywords: RNA viruses, Nora virus, picorna-like virus, virus-like particles, capsid assembly.

The gammaherpesvirus 68 viral cyclin facilitates expression of LANA

Gammaherpesviruses establish life-long infections within their host and have been shown to be the causative agents of devastating malignancies. Chronic infection within the host is mediated through cycles of transcriptionally quiescent stages of latency with periods of reactivation into detectable lytic and productive infection. The mechanisms that regulate reactivation from latency remain poorly understood. Previously, we defined a critical role for the viral cyclin in promoting reactivation from latency. Disruption of the viral cyclin had no impact on the frequency of cells containing viral genome during latency, yet it remains unclear whether the viral cyclin influences latently infected cells in a qualitative manner. To define the impact of the viral cyclin on properties of latent infection, we utilized a viral cyclin deficient variant expressing a LANA-beta-lactamase fusion protein (LANA::βla), to enumerate both the cellular distribution and frequency of LANA gene expression. Disruption of the viral cyclin did not affect the cellular distribution of latently infected cells, but did result in a significant decrease in the frequency of cells that expressed LANA::βla across multiple tissues and in both immunocompetent and immunodeficient hosts. Strikingly, whereas the cyclin-deficient virus had a reactivation defect in bulk culture, sort purified cyclin-deficient LANA::βla expressing cells were fully capable of reactivation. These data emphasize that the γHV68 latent reservoir is comprised of at least two distinct stages of infection characterized by differential LANA expression, and that a primary function of the viral cyclin is to promote LANA expression during latency, a state associated with ex vivo reactivation competence.

Gammaherpesviruses are ubiquitous viruses with oncogenic potential that establish latency for the life of the host. These viruses can emerge from latency through reactivation, a process that is controlled by the immune system. Control of viral latency and reactivation is thought to be critical to prevent γHV-associated disease. This study focuses on a virally-encoded cyclin that is required for reactivation from latency. By characterizing how the viral cyclin influences latent infection in pure cell populations, we find that the viral cyclin has a vital role in promoting viral gene expression during latency. This work provides new insight into the function of a virally encoded cyclin in promoting reactivation from latency.

Seroprevalence and associated risk factors of Toxoplasma gondii and Neospora caninum infections in cattle in Central India

Toxoplasma gondii and Neospora caninum are closely related cyst-forming parasites identified as important causes of reproductive failures in ruminants. While these parasites have been reported worldwide, seroprevalence and associated risk factors for cattle infections have not been determined in India. A total of 576 serum samples of cattle were analyzed for antibodies to T. gondii and N. caninum using enzyme-linked immunosorbent assay (ELISA), modified/Neospora agglutination test (MAT/NAT), and an indirect fluorescent antibody test (IFAT-tachyzoite and bradyzoite). Additionally, general information about cattle, movement of cats and dogs, the menace of rodents, management, and reproductive disorders were assessed to identify the potential risk factors. Overall, 32.9% (190/576) serum samples reacted positively to T. gondii and 24.8% (143/576) to N. caninum. The performance of the diagnostic tests showed excellent agreement between IFAT and ELISA (kappa [κ] = 0.98) and between MAT/NAT and ELISA (κ = 0.97). Combining both infections on avidity test, 94% sera had high-IgG avidity, and 3% had low-IgG avidity antibodies, indicating chronic infection in the majority of the cases. The identified risk factors (p < 0.05) for exposure to T. gondii were: increasing age (Odds Ratio [OR]: 2.02), movement of cat (OR: 4.8) and rodents (OR: 1.57) in the farm; and for N. caninum: increasing age (OR: 1.6), movement of dogs in the farm (OR: 2.07), drinking pond water (OR: 1.64) and abortion (OR: 1.82). These findings revealed that T. gondii and N. caninum infections are widespread in the study area and suggest conducting nationwide epidemiological studies owing to their economic importance.

Surgical Site Infection after Surgical Stabilization of Rib Fractures: Rare But Morbid

Background: Although surgical stabilization for rib fractures (SSRF) has been adopted widely over the past decade, little information is available regarding the prevalence and outcomes of post-operative surgical site infection (SSI). We hypothesized that SSI after SSRF is uncommon but morbid. Patients and Methods: Patients undergoing SSRF at a level 1 trauma center from 2010-2020 were reviewed. The primary outcome was the prevalence of SSI, documented by clinical examination, radiography, systemic markers of infection, and microbiology. Results: Of 228 patients undergoing SSRF, 167 (73.2%) were male, the median age was 53 years (P₂₅-P₇₅; 41-63 years), injury severity score (ISS) was 19 (P₂₅-P_75, 13-26), with a median of eight fractured ribs (P₂₅-P_75, 6-11). All stabilization plates were titanium. SSRF was typically performed on post-injury day one (P₂₅-P_75, 0-2 days) after trauma. All patients received antibiotic agents within 30 minutes of incision, and a median of four ribs (P₂₅-P_75, 3-6) were repaired. Four (1.8%) patients developed an SSI and all underwent implant removal. Two patients required implant removal within 30 days (on post-operative day seven and 17) and two for chronic infection at seven and 17 months after SSRF. The causative organism was methicillin-sensitive Staphylococcus aureus (MSSA) bacteria in all patients. After implant removal, three patients received intravenous and oral antibiotic agents, ranging from two to six weeks, without recurrent infection. No patient required additional SSRF. Conclusions: Surgical site infection after SSRF is rare but morbid and can become symptomatic within one week to 17 months. Implant removal results in complete recovery.

A Novel Subtype of Bovine Hepacivirus Identified in Ticks Reveals the Genetic Diversity and Evolution of Bovine Hepacivirus

Hepaciviruses represent a group of viruses that pose a significant threat to the health of humans and animals. New members of the genus Hepacivirus in the family Flaviviridae have recently been identified in a wide variety of host species worldwide. Similar to the Hepatitis C virus (HCV), bovine hepacivirus (BovHepV) is hepatotropic and causes acute or persistent infections in cattle. BovHepVs are distributed worldwide and classified into two genotypes with seven subtypes in genotype 1. In this study, three BovHepV strains were identified in the samples of ticks sucking blood on cattle in the Guangdong province of China, through unbiased high-throughput sequencing. Genetic analysis revealed the polyprotein-coding gene of these viral sequences herein shared 67.7–84.8% nt identity and 76.1–95.6% aa identity with other BovHepVs identified worldwide. As per the demarcation criteria adopted for the genotyping and subtyping of HCV, these three BovHepV strains belonged to a novel subtype within the genotype 1. Additionally, purifying selection was the dominant evolutionary pressure acting on the genomes of BovHepV, and genetic recombination was not common among BovHepVs. These results expand the knowledge about the genetic diversity and evolution of BovHepV distributed globally, and also indicate genetically divergent BovHepV strains were co-circulating in cattle populations in China.

Herpes Zoster After Tocilizumab Therapy in COVID-19 Survivor: A Case Report

The COVID-19 pandemic has become a concern for the world community. However, despite abundant attempts taking place, there is currently no definitive therapy for COVID-19 yet. The clinical approaches recently adopted are the provision of antiviral therapy and immunomodulators. One of the immunomodulators that are currently being researched is tocilizumab, an IL-6 receptor antagonist monoclonal antibody. Many case studies and retrospective observational studies have shown that there is a chance that tocilizumab could diminish death rates in COVID-19 patients with severe or critical symptoms. Along with the growing use of tocilizumab in the COVID-19 cases that are emergent in nature, the occurrence of unpredictable adverse effects of the drugs have also been raising.  This case report describes a COVID-19 confirmed patient with severe symptoms who was given tocilizumab in addition to standard therapy. The patient developed Herpes Zoster infection which was suspected to be related to the adverse effects of using tocilizumab, which is known for its likelihood to increase the risk of new infections and also probably reactivate latent infections. Tocilizumab use seems to be effective in combating cytokine storm associated with severe COVID-19 infection. The possibility of serious adverse effects in the utilization of tocilizumab, though rare, cannot be excluded. The presence of a latent or chronic infection that can undergo reactivation should be a consideration for appropriate screening or prophylaxis before administering tocilizumab.

[Clinical practice guidelines for the diagnosis and management chronic infection of hepatitis viral C of the Peruvian Health Social Security (EsSalud)]

INTRODUCTION

This article summarizes the clinical practice guidelines (CPG) for the diagnosis and treatment of chronic infection of hepatitis viral C of the Peruvian Health Social Security (EsSalud).

OBJECTIVE

To provide clinical recommendations based on evidence for the diagnosis and treatment of chronic infection of hepatitis viral C in EsSalud.

METHODS

A guideline development group (GDG) was established, including medical specialists and methodologists. The GDG formulated 4 clinical questions to be answered in this CPG. Systematic searches of systematic reviews and primary studies (when pertinent) were conducted in PubMed, and Central (Cochrane) during 2019. The evidence was selected to answer each of the clinical questions. The accuracy of the evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. In periodic work meetings, the GEG used the GRADE methodology to review the evidence and formulate the recommendations, the points of good clinical practice and the treatment flowchart. Finally, the CPG was approved with Resolution No. 151-IETSIESSALUD-2019.

RESULTS

The present CPG addressed 4 clinical questions of four topics: screening, diagnosis, staging and treatment. Based on these questions, 13 recommendations (8 strong recommendations and 5 weak recommendations), 27 points of good clinical practice, and 1 flowchart were formulated.

CONCLUSION

This paper summarizes the methodology and evidencebased conclusions from the CPG for for the diagnosis and treatment of chronic infection of hepatitis viral C of the EsSalud.

The Not-So-Good, the Bad and the Ugly: HPV E5, E6 and E7 Oncoproteins in the Orchestration of Carcinogenesis

Infection with HPV starts with the access of the viral particles to basal cells in the epidermis, potentially via microtraumas to the skin. The basal cells are able to keep away these pathogens in normal circumstances through a robust immune response from the host, as HPV infections are, in general, cleared within 2 to 3 weeks. However, the rare instances of persistent infection and/or in cases where the host immune system is compromised are major risk factors for the development of lesions potentially leading to malignancy. Evolutionarily, obligatory pathogens such as HPVs would not be expected to risk exposing the host to lethal cancer, as this would entail challenging their own life cycle, but infection with these viruses is highly correlated with cancer and malignancy-as in cancer of the cervix, which is almost always associated with these viruses. Despite this key associative cause and the availability of very effective vaccines against these viruses, therapeutic interventions against HPV-induced cancers are still a challenge, indicating the need for focused translational research. In this review, we will consider the key roles that the viral proteins play in driving the host cells to carcinogenesis, mainly focusing on events orchestrated by early proteins E5, E6 and E7-the not-so-good, the bad and the ugly-and discuss and summarize the major events that lead to these viruses mechanistically corrupting cellular homeostasis, giving rise to cancer and malignancy.

Genome Sequences of Two Pseudomonas aeruginosa Isolates with Defects in Type III Secretion System Gene Expression from a Chronic Ankle Wound Infection

Effector proteins translocated into host cells by the Pseudomonas aeruginosa type III secretion system (T3SS) are critical for phagocytic avoidance and systemic spread of the microorganism. The T3SS genes are present in virtually all P. aeruginosa strains. When examined in environmental isolates and clinical specimens, expression of the T3SS genes is the rule. Isolates from the airways of cystic fibrosis (CF) patients are one exception, and these isolates usually carry mutations that disable T3SS gene expression. In this study, we describe two P. aeruginosa isolates, one pigmented brown and one green, from a keratitis-ichthyosis-deafness (KID) syndrome patient with a chronic cutaneous ankle wound. Similar to most isolates from CF, both of the KID isolates were defective for T3SS gene expression. Providing the primary activator of T3SS transcription (exsA) in trans restored T3SS function. Since the exsA sequences were identical to that of a reference strain with active T3SS gene expression, we examined the cAMP-Vfr system, a critical regulator of T3SS gene expression. Vfr is a cAMP-dependent transcription factor that activates exsA expression. Whereas T3SS activity was corrected in the brown isolate by restoring cAMP synthesis, the same was not observed for the green isolate. These findings suggest that distinct mechanisms resulted in loss of T3SS gene expression in the KID isolates. The mutations responsible for the T3SS defects were not clearly evident by comparison of the whole-genome sequences to a reference strain. Our findings suggest that loss of T3SS gene expression may be a trait common to both CF and non-CF chronic infections. IMPORTANCE A common feature of microorganisms that cause chronic infections is a stealthy lifestyle that promotes immune avoidance and host tolerance. During chronic colonization of cystic fibrosis (CF) patients, Pseudomonas aeruginosa acquires numerous adaptations that include reduced expression of some factors, such as motility, O antigen, and the T3SS, and increased expression of other traits, such as biofilm formation. In this study, we report loss of T3SS gene expression in non-CF chronic isolates. This finding suggests that loss of the T3SS may be a common and important trait that contributes to persistence and may open avenues to explore the significance further using non-CF chronic infection models.

Hepatitis C Virus Vaccine Research: Time to Put Up or Shut Up

Unless urgently needed to prevent a pandemic, the development of a viral vaccine should follow a rigorous scientific approach. Each vaccine candidate should be designed considering the in-depth knowledge of protective immunity, followed by preclinical studies to assess immunogenicity and safety, and lastly, the evaluation of selected vaccines in human clinical trials. The recently concluded first phase II clinical trial of a human hepatitis C virus (HCV) vaccine followed this approach. Still, despite promising preclinical results, it failed to protect against chronic infection, raising grave concerns about our understanding of protective immunity. This setback, combined with the lack of HCV animal models and availability of new highly effective antivirals, has fueled ongoing discussions of using a controlled human infection model (CHIM) to test new HCV vaccine candidates. Before taking on such an approach, however, we must carefully weigh all the ethical and health consequences of human infection in the absence of a complete understanding of HCV immunity and pathogenesis. We know that there are significant gaps in our knowledge of adaptive immunity necessary to prevent chronic HCV infection. This review discusses our current understanding of HCV immunity and the critical gaps that should be filled before embarking upon new HCV vaccine trials. We discuss the importance of T cells, neutralizing antibodies, and HCV genetic diversity. We address if and how the animal HCV-like viruses can be used for conceptualizing effective HCV vaccines and what we have learned so far from these HCV surrogates. Finally, we propose a logical but narrow path forward for HCV vaccine development.

Clinical Course of Infection and Cross-Species Detection of Equine Parvovirus-Hepatitis

Since its first discovery by Arnold Theiler in 1918, serum hepatitis also known as Theiler’s disease has been reported worldwide, causing idiopathic acute hepatitis and liver failure in horses. Recent studies have suggested a novel parvovirus, named equine parvovirus hepatitis (EqPV-H), to be associated with Theiler’s disease. Despite the severity and potential fatality of EqPV-H infection, little is known about the possibility of developing chronic infections and putative cross-species infection of equine sister species. In the present longitudinal study, we employed qPCR analysis, serology, and biochemical testing as well as pathology examination of liver biopsies and sequence analysis to investigate potential chronic EqPV-H infection in an isolated study cohort of in total 124 horses from Germany over five years (2013–2018). Importantly, our data suggest that EqPV-H viremia can become chronic in infected horses that do not show biochemical and pathological signs of liver disease. Phylogenetic analysis by maximum likelihood model also confirms high sequence similarity and nucleotide conservation of the multidomain nuclear phosphoprotein NS1 sequences from equine serum samples collected between 2013–2018. Moreover, by examining human, zebra, and donkey sera for the presence of EqPV-H DNA and VP1 capsid protein antibodies, we found evidence for cross-species infection in donkey, but not to human and zebra. In conclusion, this study provides proof for the occurrence of persistent EqPV-H infection in asymptomatic horses and cross-species EqPV-H detection in donkeys.

Prevalence and Predictors of Persistent Human Immunodeficiency Virus Viremia and Viral Rebound After Universal Test and Treat: A Population-Based Study

BACKGROUND

There are limited data on individual human immunodeficiency virus (HIV) viral load (VL) trajectories at the population-level after the introduction of universal test and treat (UTT) in sub-Saharan Africa.

METHODS

Human immunodeficiency virus VLs were assessed among HIV-positive participants through 3 population-based surveys in 4 Ugandan fishing communities surveyed between November 2011 and August 2017. The unit of analysis was a visit-pair (2 consecutive person-visits), which were categorized as exhibiting durable VL suppression, new/renewed VL suppression, viral rebound, or persistent viremia. Adjusted relative risks (adjRRs) and 95% confidence intervals (CIs) of persistent viremia were estimated using multivariate Poisson regression.

RESULTS

There were 1346 HIV-positive participants (n = 1883 visit-pairs). The population-level prevalence of durable VL suppression increased from 29.7% to 67.9% during UTT rollout, viral rebound declined from 4.4% to 2.7%, and persistent viremia declined from 20.8% to 13.3%. Younger age (15-29 vs 40-49 years; adjRR = 1.80; 95% CI = 1.19-2.71), male sex (adjRR = 2.09, 95% CI = 1.47-2.95), never being married (vs currently married; adjRR = 1.88, 95% CI = 1.34-2.62), and recent migration to the community (vs long-term resident; adjRR = 1.91, 95% CI = 1.34-2.73) were factors associated with persistent viremia.

CONCLUSIONS

Despite increases in durable VL suppression during roll out of UTT in hyperendemic communities, a substantial fraction of the population, whose risk profile tended to be younger, male, and mobile, remained persistently viremic.

Development of a Recombinase Polymerase Amplification (RPA) assay for acute hepatopancreatic necrosis disease (AHPND) detection in Pacific white shrimp (Penaeus vannamei)

Acute hepatopancreatic necrosis disease (AHPND) is currently the most important bacterial disease of shrimp that has caused enormous losses to the shrimp industry worldwide. The causative agent of AHPND are Vibrio spp. Carrying plasmids containing the pirA and pirB genes which encode binary toxins, PirAB. Currently, AHPND is mostly diagnosed by PCR-based platforms which require the use of sophisticated laboratory instrumentation and are not suitable for a point-of-care diagnostics. Therefore, the availability of an alternative method based on isothermal amplification would be suitable for AHPND detection outside a laboratory setting and extremely useful at a pond side location. Isothermal amplification is based on the nucleic acid amplification at a single temperature and does not require the use of a thermal cycler. In this study, we developed an isothermal Recombinase Polymerase Amplification (RPA) assay for AHPND detection targeting both pirA and pirB genes, simultaneously and evaluated the specificity and sensitivity of the assay. The assay could detect AHPND without any cross-reaction with other microbial pathogens and Specific Pathogen Free (SPF) shrimp. The limit of detection of the assay was 5 copies of pirAB genes. To evaluate the reliability of the assay in detecting AHPND, DNA from Penaeus vannamei shrimp displaying acute and chronic infection were analyzed by the RPA assay and the results were compared with SYBR Green real-time PCR assay. While there was a 100% conformity between the two assay while detecting acute phase infection, RPA appeared to be more sensitive in detecting chronic phase infection. The data suggest that RPA assay described here would be a reliable method in detecting AHPND outside a standard laboratory setting.

Seroprevalence and characterisation of herpes simplex virus from human immunodeficiency virus in samples collected from two provinces in South Africa: a retrospective study

Background: Herpes simplex virus (HSV) is a widely distributed human pathogen that is known for its ulcerative lesions at the infection site. HSV can cause persistent infection in the host that is often followed by a period of latency within the neurons. Considering the high rate of HIV infection in South Africa, it is important to assess the seroprevalence of HSV with a focus to determine the epidemiological association between HSV-DNA and HIV-1 in the population. Methods: A total of 44 sera samples were screened for HSV and HIV-1 using the highly sensitive enzyme-linked immunosorbent assay (ELISA). The ELISA positive samples were characterized using polymerase chain reaction (PCR) to confirm the positivity of both viruses and to further differentiate HSV into HSV-1 and -2. Thereafter, the samples were analysed for relatedness using phylogenetic analysis. Results: Of the 44 samples, 36 (81.8%) were positive for HIV-1, while 35 (79.5%) were positive for HSV when screened with ELISA kits. The PCR results, with the use of type specific primers, showed that 4/35 (11.4%) samples were specific for HSV-1 while 30/35 (85.7%) were specific for HSV-2. Statistical analysis performed using the chi-squared goodness-of-fit test showed that there is a significant relationship between HSV-2 and HIV-1 transmission. Conclusions: The prevalence of HSV in the population is high with an increased HSV-2 infection in women. Our study shows that some of the HSV-2 isolates are not related to the clinical isolate SD90e from South Africa, suggesting diversity in HSV-2 viral transmission.

Seroprevalence and characterisation of herpes simplex virus from human immunodeficiency virus in samples collected from two provinces in South Africa: a retrospective study

Background: Herpes simplex virus (HSV) is a widely distributed human pathogen that is known for its ulcerative lesions at the infection site. HSV can cause persistent infection in the host that is often followed by a period of latency within the neurons. Considering the high rate of HIV infection in South Africa, it is important to assess the seroprevalence of HSV with a focus to determine the epidemiological association between HSV-DNA and HIV-1 in the population. Methods: A total of 44 sera samples were screened for HSV and HIV-1 using the highly sensitive enzyme-linked immunosorbent assay (ELISA). The ELISA positive samples were characterized using polymerase chain reaction (PCR) to confirm the positivity of both viruses and to further differentiate HSV into HSV-1 and -2. Thereafter, the samples were analysed for relatedness using phylogenetic analysis. Results: Of the 44 samples, 36 (81.8%) were positive for HIV-1, while 35 (79.5%) were positive for HSV when screened with ELISA kits. The PCR results, with the use of type specific primers, showed that 4/35 (11.4%) samples were specific for HSV-1 while 30/35 (85.7%) were specific for HSV-2. Statistical analysis performed using the chi-squared goodness-of-fit test showed that there is a significant relationship between HSV-2 and HIV-1 transmission. Conclusions: There is a significant positive association between HSV-2 and HIV-1 in the study population. Our study shows that some of the HSV-2 isolates are not related to the clinical isolate SD90e from South Africa, suggesting diversity in HSV-2 viral transmission.

Seroprevalence and characterisation of herpes simplex virus from human immunodeficiency virus in samples collected from the North-West and KwaZulu-Natal Provinces: a retrospective study

Background: Herpes simplex viruses (HSVs) are highly pervasive and show a strong synergistic interaction with human immunodeficiency virus (HIV). High prevalence of HSV type 1 (HSV-1) has been reported in Africa with a prevalence rate of 20-80% in women and 10-50% in men. Studies on the prevalence of HSV in South Africa are few considering the rate of HIV infection in the country. Our focus was to determine the molecular prevalence of HSV-DNA in HIV-1 sera. Methods: In total, 44 convenience samples were screened for HSV and HIV-1 using the highly sensitive enzyme-linked immunosorbent assay (ELISA). The ELISA positive samples were characterized using polymerase chain reaction (PCR) to confirm the positivity of both viruses and to further differentiate HSV into HSV-1 and -2. Thereafter, the samples were analysed for relatedness using phylogenetic analysis. Results: Of 44 samples, 36 (81.8%) were positive for HIV-1, while 35 (79.5%) were positive for HSV when screened with ELISA kits. The results of PCR with type specific primers showed that 4/35 (11.4%) samples were specific for HSV-1 while 30/35 (85.7%) were specific for HSV-2. Statistical analysis performed using chi-squared goodness-of-fit test showed that there is a significant relationship between HSV-2 and HIV-1 transmission. Conclusions: High prevalence of HSV-2 recorded in HIV-1 sera corroborate with similar studies conducted within different cohorts in the continent. SPSS Pearson's chi-squared test established that there is a significant relationship between HSV-2 and HIV-1 transmission.