Origins of the problematic E in SEIR epidemic models

During the COVID-19 pandemic, over one thousand papers were published on "Susceptible-Exposed-Infectious-Removed" (SEIR) epidemic computational models. The English word "exposed" in its vernacular and public health usage means a state of having been in contact with an infectious individual, but not necessarily infected. In contrast, the term "exposed" in SEIR modeling usage typically stands for a state of already being infected but not yet being infectious to others, a state more properly termed "latently infected." In public health language, "exposed" means possibly infected, yet in SEIR modeling language, "exposed" means already infected. This paper retraces the conceptual and mathematical origins of this terminological disconnect and concludes that epidemic modelers should consider using the "SLIR" notational short-hand (L for Latent) instead of SEIR.

Latent tuberculosis prevalence, diagnosis and treatment in Multiple Sclerosis as a strategy for reducing infection reactivation during immunosuppressant therapy

BACKGROUND

Tuberculosis is an infectious disease with a risk of reactivation in Multiple Sclerosis patients on immunosuppressant therapy. Diagnosis and treatment of Latent Tuberculosis Infection (LTBI) prevents the infection.

OBJECTIVE

To diagnose and treat LTBI in Multiple Sclerosis (MS).

METHODS

Cross-sectional study of the prevalence and treatment of LTBI in MS, between February 2021 and June 2023. LTBI was defined as an absence of symptoms, positive PPD or IGRA and normal chest X-ray.

RESULTS

Of the 58 patients with MS, 17 (29.3 %) were diagnosed with LTBI, 15 with PPD > 5 mm and 2 with positive IGRA, 10 (58.8 %) female and 7 (41.1 %) male, mean age of 41.3 (SD ±13.4) years. All patients with LTBI were treated with immunomodulators or immunosuppressants: Fingolimod 5 (29.4 %), Natalizumab 5 (29.4 %), Cladribine 2 (11.8 %), Glatiramer 2 (11.8 %), Ocrelizumab 2 (11.8 %), and Interferon beta 1 (5.9 %). Steroids therapy for relapses, were used in 5/17 (93.8 %) with LTBI and 30/37 (81.1 %) without LTBI. To treat LTBI, 11 (64.7 %) received Isoniazid and 6 (35.3 %) Isoniazid plus Rifapentine. Hepatotoxicity occurred in 3 (17.6 %) with INH. There were no interruptions of ILTB treatment during the study.

CONCLUSION

The prevalence of LTBI was found to be high and treatment proved safe.

[Study on risk factors of mycobacterium tuberculosis infection among health workers in medical institutions]

Objective: To understand the infection status of mycobacterium tuberculosis among health workers in tuberculosis designated medical institutions and explore the risk factors of infection. Methods: From September 2021 to June 2022, a questionnaire survey was conducted among health workers in relevant departments of 4 tuberculosis designated medical institutions by cluster stratified sampling, including the implementation of hospital infection control measures in medical institutions and occupational exposure of medical staff to mycobacterium tuberculosis. Peripheral blood interferon gamma release assays (IGRAs) and lung imaging examination were performed to determine the mycobacterium tuberculosis infection. Factors with statistical significance in univariate analysis were included in multivariate logistic regression to analyze the risk factors of mycobacterium tuberculosis infection. Results: A total of 657 people completed the lung imaging examination and questionnaire, of which 654 people had peripheral blood IGRAs detection, and the latent infection rate of tuberculosis was 39.45% (258/654) . Univariate analysis showed that age, sex, marital status, economic income, occupational category, professional title, length of service, and other variables had statistical significances in tuberculosis latent infection (P<0.05) . In terms of personal health status, there were statistically significant differences in the distribution of health workers in terms of their tuberculosis history, tuberculosis history of their immediate family members, previous tuberculin skin test (TST) (P<0.05) . Multivariate analysis showed that there were four risk factors related to tuberculosis, including professional title (X(1)) , years of tuberculosis related works (X(2)) , tuberculosis history (X(3)) and previous TST (X(4)) . The regression equation of the probability of tuberculosis among health workers was y=-1.920+0.246X(1)+0.046X(2)+1.231X(3)+0.478X(4). Conclusion: The latent infection rate of tuberculosis among health workers in tuberculosis designated medical institutions is high. It is necessary to strengthen the management of infection control, carry out regular screening, enhance the self-protection awareness of health workers, and reduce their exposure to mycobacterium tuberculosis and infection risk.

The role and mechanisms of PD-L1 in immune evasion during Talaromyces marneffei infection

Talaromycosis, caused by Talaromyces marneffei (T. marneffei), is a systemic fungal disease that involves dissemination throughout the body. The ability of T. marneffei to evade the immune system is considered a crucial factor in its persistent infection, although the specific mechanisms are not yet fully understood. This study aims to investigate the molecular mechanisms underlying the occurrence of latent T. marneffei infection and immune evasion. The gene expression profile analysis in T. marneffei-infected mouse revealed that Pd-l1 exhibited the highest correlation strength with other hub genes, with a median of 0.60 (IQR: 0.50-0.69). T. marneffei infection upregulated the expression of PD-1 and PD-L1 in PBMCs from HIV patients, which was also observed in the T. marneffei-infected mouse and macrophage models. Treatment with a PD-L1 inhibitor significantly reduced fungal burden in the liver and spleen tissues of infected mice and in the kupffer-CTLL-2 co-culture system. PD-L1 inhibitor treatment increased CTLL-2 cell proliferation and downregulated the expression of PD-1, SHP-2, and p-SHP-2, indicating the activation of T cell viability and T cell receptor signaling pathway. Additionally, treatment with a PI3K inhibitor downregulated PD-L1 in T. marneffei-infected kupffer cells. Similar results were observed with treatment using the T. marneffei cell wall virulence factor β-glucan. Overall, T. marneffei infection upregulated PD-L1 expression in HIV / T. marneffei patients, mice, and kupffer cells. Treatment with a PD-L1 inhibitor significantly reduced fungal burden, while activating T cell activity and proliferation, thereby promoting fungal clearance. Furthermore, the PI3K signaling pathway may be involved in the regulation of PD-L1 by T. marneffei.

Construction of a murine model of latent infection and reactivation induced by Talaromyces marneffei

OBJECTIVE

To establish a murine model of Talaromyces marneffei (T. marneffei) latent infection and reactivation, providing a foundation for exploring the molecular mechanisms underlying disease relapse.

METHODS

BALB/c mice were tail vein injected with T. marneffei at 0 days post-infection (dpi) and treated with cyclophosphamide (CTX) intraperitoneally every four days, starting from 21 dpi or 42 dpi. Mice were observed for body weight changes, liver and spleen indices, histological characteristics of liver and spleen, fungal load detection in liver and spleen, and Mp1p qualitation in liver and spleen to assess T. marneffei infection severity.

RESULTS

T. marneffei-infected mice exhibited a trend of initial weight loss followed by recovery and a subsequent decrease in weight after CTX injection throughout the observation period. Liver and spleen indices, as well as tissue damage, significantly increased during infection but later returned to normal levels, with a gradual rise observed after immunosuppression. Fungal load analysis revealed positive T. marneffei cultures in the liver and spleen at 7 dpi and 14 dpi, followed by negative T. marneffei cultures from 21 dpi until day 21 post-immunosuppression (42 dpi or 63 dpi); however, the spleen remained T. marneffei-cultured negative, consistent with the trend observed in Mp1p detection results.

CONCLUSION

A latent infection and reactivation model of T. marneffei in mice was successfully established, with the liver likely serving as a key site for latent T. marneffei.

The MEF2 homolog of Penaeus vannamei is essential for maintaining the WSSV latent infection

White spot syndrome virus (WSSV) is a lethal shrimp pathogen that has a latent infection cycle. The latent virus can easily turn into an acute infection when the culture environment changes, leading to widespread shrimp mortality. However, the mechanism of WSSV latent infection is poorly understood. Bioinformatic analysis revealed that the promoters of WSSV latency-related genes (i.e., wsv151, wsv366, wsv403, and wsv427) contained putative myocyte enhancer factor 2 (MEF2) binding sites. This suggested that the transcription factor MEF2 may be involved in WSSV latent infection. To further investigate this, a MEF2 homolog (PvMEF2) was cloned from Penaeus vannamei and its role in WSSV latent infection was explored. The results showed that knockdown of PvMEF2 led to an increase in the copy number of WSSV, indicating reactivation of WSSV from a latent infection. It was further demonstrated that suppression of PvMEF2 significantly decreased expression of the viral latency-related genes in WSSV-latent shrimp, while overexpression of PvMEF2 in Drosophila S2 cells activated the promoter activity of the viral latency-related gene. Additionally, we demonstrated that silencing of PvMEF2 was able to upregulate the expression of pro-apoptosis genes, thereby promoting cell apoptosis during latent infection. Collectively, the present data suggest that PvMEF2 could promote the expression of virus latency-related genes and enhance cell survival to maintain WSSV latent infection. This finding would contribute to a better understanding of the maintenance mechanism of WSSV latent infection.

Tuberculosis preventive treatment in children and adolescents: an observational study of secondary data

OBJECTIVE

To analyze the effectiveness, safety, outcomes, and associated factors of tuberculosis preventive treatment (TPT) in children and adolescents in Paraná, southern Brazil.

METHOD

This was an observational cohort study with a retrospective collection of secondary data from the TPT information systems of the state of Paraná from 2009 to 2016, and tuberculosis in Brazil from 2009 to 2018.

RESULTS

In total, 1,397 people were included. In 95.4% of the individuals, the indication for TPT was a history of patient-index contact with pulmonary tuberculosis. Isoniazid was used in 99.9% of the cases with TPT, and 87.7% completed the treatment. The TPT protection was 98.7%. Among the 18 people who had TB, 14 (77.8%) became ill after the second year of treatment, and four (22.2%) in the first two years (p < 0.001). Adverse events were reported in 3.3% of cases, most of them were gastrointestinal and medication was discontinued in only 2 (0.1%) patients. No risk factors associated with the illness were observed.

CONCLUSIONS

The authors observed a low rate of illness in pragmatics routine conditions in TPT for children and adolescents, especially within the first two years after the end of treatment, with good tolerability and a good percentage of adherence to the treatment. TPT should be encouraged to achieve the goals of the End TB Strategy of the World Health Organization as an essential strategy to reduce the incidence rate of the disease, but studies with new schemes must continue to be carried out in real-life scenarios.

Antigen specificities of HIV-infected cells: A role in infection and persistence?

Antigen-experienced memory CD4⁺ T cells are the major target of HIV infection and support both productive and latent infections, thus playing a key role in HIV dissemination and persistence, respectively. Here, we reviewed studies that have shown direct association between HIV infection and antigen specificity. During untreated infection, some HIV-specific cells host productive infection, while other pathogen-specific cells such as cytomegalovirus (CMV) and Mycobacterium tuberculosis also contribute to viral persistence on antiretroviral therapy (ART). These patterns could be explained by phenotypic features differing between these pathogen-specific cells. Mechanisms involved in these preferential infection and selection processes include HIV entry and restriction, cell exhaustion, survival, self-renewal and immune escape. For instance, MIP-1β expressing cells such as CMV-specific memory cells were shown to resist infection by HIV CCR5 coreceptor downregulation/inhibition. Conversely, HIV-infected CMV-specific cells undergo clonal expansion during ART. We have identified several research areas that need further focus such as the role of other pathogens, viral genome intactness, inducibility and phenotypic features. However, given the sheer diversity of both the CD4⁺ T cell repertoire and antigenic history of each individual, studying HIV-infected, antigen-experienced cells still imposes numerous challenges.

Temperature-regulated type II grass carp reovirus establishes latent infection in Ctenopharyngodon idella brain

Grass carp reovirus (GCRV) causes extensive infection and death in grass carp and black carp fingerlings, with a highly seasonal prevalence. Previous studies suggested that GCRV can become latent after primary infection. In this study, we investigated type II GCRV (GCRV-II) latency in asymptomatic grass carp with GCRV infection or exposure history. We found that during latent infection, GCRV-II was detectable only in the brain of grass carp, unlike the multi-tissue distribution observed in natural infection. GCRV-II only caused damage to the brain during latent infection, while in natural infection, brain, heart, and eye tissues had relatively higher viral loads. We also discovered viral inclusion bodies in infected fish brains. Additionally, GCRV-II distribution in grass carp was notably affected by ambient temperature, with the virus targeting the brain only during low temperatures and multi-tissue distribution during high temperatures. This study provides insights into the mechanisms of GCRV-II latent infection and reactivation and contributes to the prevention and control of GCRV pandemics.

Stability of a delayed SARS-CoV-2 reactivation model with logistic growth and adaptive immune response

This paper develops and analyzes a SARS-CoV-2 dynamics model with logistic growth of healthy epithelial cells, CTL immune and humoral (antibody) immune responses. The model is incorporated with four mixed (distributed/discrete) time delays, delay in the formation of latent infected epithelial cells, delay in the formation of active infected epithelial cells, delay in the activation of latent infected epithelial cells, and maturation delay of new SARS-CoV-2 particles. We establish that the model's solutions are non-negative and ultimately bounded. We deduce that the model has five steady states and their existence and stability are perfectly determined by four threshold parameters. We study the global stability of the model's steady states using Lyapunov method. The analytical results are enhanced by numerical simulations. The impact of intracellular time delays on the dynamical behavior of the SARS-CoV-2 is addressed. We noted that increasing the time delay period can suppress the viral replication and control the infection. This could be helpful to create new drugs that extend the delay time period.

COVID-19 infection and vaccines: potential triggers of Herpesviridae reactivation

Since the onset of the COVID-19 outbreak, numerous articles have highlighted a possible link between COVID-19 vaccination or infection and Herpesviridae co-infection or reactivation. The authors conducted an exhaustive literature review on this topic, the results of which are presented individually for each member of the Herpesviridae family: Herpes Simplex Virus (HSV) types-1 (HSV-1) and 2 (HSV-2); Varicella-Zoster Virus (VZV); Epstein-Barr Virus (EBV); Cytomegalovirus (CMV); HHV-6; HHV-7; and HHV-8. These human herpesviruses can serve as prognostic markers for the COVID-19 infection and may even underlie some of the clinical manifestations initially attributed to SARS-CoV-2. In addition to SARS-CoV-2 infection, all corresponding vaccines approved to date in Europe appear capable of inducing herpesvirus reactivation. It is important to consider all viruses of the Herpesviridae family when managing patients infected with or recently vaccinated against COVID-19.

Mouse Model of Latent Cryptococcal Infection and Reactivation

AbstractCryptococcus neoformans is an opportunistic fungal pathogen that frequently causes fatal meningoencephalitis in patients with impaired immune responses. This fungus, an intracellularly growing microbe, evades host immunity, leading to a latent infection (latent C. neoformans infection: LCNI), and cryptococcal disease is developed by its reactivation when host immunity is suppressed. Elucidation of the pathophysiology of LCNI is difficult due to the lack of mouse models. Here we show the established methods for LCNI and reactivation.

Antiviral therapy use and related outcomes in patients with cancer and viral infections: results from SWOG S1204

PURPOSE

Information is limited about adherence to practice guidelines in patients with hepatitis B virus (HBV), hepatitis C virus (HCV), or HIV infection receiving anticancer treatment.

METHODS

Newly diagnosed adult cancer patients were enrolled in a multicenter, prospective cohort study (SWOG S1204) during 2013-2017 to evaluate the prevalence of HBV, HCV, or HIV in patients initiating anticancer treatment. At 6 months, records of virus-positive patients were reviewed for antiviral therapy use; anticancer treatment dose reduction; and HBV reactivation (elevated viral load). Categorical variables were compared using chi-square or Fisher's exact test.

RESULTS

Of 3055 enrolled patients with viral testing, 230 had chronic or past HBV, HCV, or HIV with 6-month follow-up data (chronic HBV, 15 patients; past HBV, 158; HCV, 49; HIV, 30). Twenty percent (3/15) of chronic HBV and 11% (17/158) of past HBV patients were co-infected with HCV and/or HIV. Rates of antiviral therapy use by 6 months were as follows: chronic HBV, 85% (11/13); past HBV receiving anti-B cell therapy, 60% (3/5); past HBV receiving systemic anticancer therapy without anti-B cell therapy, 8% (8/105); HCV, 6% (2/35); and HIV, 90% (19/21). Among patients with available data, anticancer treatment dose was reduced in 1 of 145 patients with past HBV and 1 of 42 with HCV. HBV reactivation occurred in 1 of 15 patients with chronic HBV; this patient was not receiving antiviral therapy.

CONCLUSION

Many patients with cancer and viral infections either do not receive guideline-recommended antiviral treatment or receive antiviral treatment that is not recommended in guidelines. Further education is needed to improve adherence to guidelines.

Molecular epidemiology on seasonal variation of yellow mosaic disease incidence in blackgram (Vigna mungo L. Hepper) with its vector Bemisia tabaci

The yellow mosaic disease (YMD) of blackgram caused by Mungbean yellow mosaic virus has emerged as a serious threat to grain legume production, especially in Southeastern Asia. Seasonal incidence of YMD with its vector population was assessed in three different agroclimatic zones of Tamil Nadu in India for three consecutive cropping seasons namely, Rabi 2018 (October-December), Summer 2019 (March-May), and Kharif 2019 (June-August) at three different time intervals viz., 20, 40, and 60 days after sowing (DAS). For all three seasons, disease incidence and whitefly count were recorded for a resistant and susceptible variety of blackgram in fields without any vector control intervention. The highest disease incidence (87%) was observed in the Panpozhi location during the summer season followed by Vamban and Coimbatore locations. The whitefly count was made through both visual count and yellow sticky traps. The whitefly population was highest at 20 DAS and decreased with the increasing age of crop for all the three locations assessed. Molecular epidemiology was analyzed by determining latent infection of mungbean yellow mosaic virus (MYMV) using molecular diagnosis. Latent infection was found to be well pronounced in the Coimbatore location during the Kharif season, where the crop was asymptomatic in both the resistant and susceptible varieties for all the three time periods assessed. The latent infection of MYMV observed in Coimbatore and Vamban ranged from 16.6 to 83.3% in both resistant and susceptible varieties for all three seasons. In Panpozhi, the latent infection of MYMV ranged from 16.6 to 66.6% for the susceptible variety (CO-5) for all three seasons observed. However, in the Panpozhi location, the resistant variety (VBN-8) failed to record any latent infection.

Innate immune regulation in HIV latency models

BACKGROUND

Innate immunity and type 1 interferon (IFN) defenses are critical for early control of HIV infection within CD4 + T cells. Despite these defenses, some acutely infected cells silence viral transcription to become latently infected and form the HIV reservoir in vivo. Latently infected cells persist through antiretroviral therapy (ART) and are a major barrier to HIV cure. Here, we evaluated innate immunity and IFN responses in multiple T cell models of HIV latency, including established latent cell lines, Jurkat cells latently infected with a reporter virus, and a primary CD4 + T cell model of virologic suppression.

RESULTS

We found that while latently infected T cell lines have functional RNA sensing and IFN signaling pathways, they fail to induce specific interferon-stimulated genes (ISGs) in response to innate immune activation or type 1 IFN treatment. Jurkat cells latently infected with a fluorescent reporter HIV similarly demonstrate attenuated responses to type 1 IFN. Using bulk and single-cell RNA sequencing we applied a functional genomics approach and define ISG expression dynamics in latent HIV infection, including HIV-infected ART-suppressed primary CD4 + T cells.

CONCLUSIONS

Our observations indicate that HIV latency and viral suppression each link with cell-intrinsic defects in specific ISG induction. We identify a set of ISGs for consideration as latency restriction factors whose expression and function could possibly mitigate establishing latent HIV infection.

Disseminated Kaposi sarcoma following COVID-19 in a 61-year-old Albanian immunocompetent man: a case report and review of the literature

Background

COVID-19 and its related anti-inflammatory treatment (steroids, immunomodulators) may induce the reactivation of latent bacterial, parasitic, and viral infections. According to our knowledge, no case of disseminated HHV-8-related Kaposi sarcoma (KS) after COVID-19 and its treatment has been described so far. Only one case of cutaneous KS concurrently with COVID-19 has been previously reported.

Case presentation

We describe a case of disseminated KS in a 61-year-old immunocompetent Albanian man after hospitalization for COVID-19.

Methods for literature research

We used PubMed as biomedical database for the literature research. We selected keyword combinations including “Kaposi sarcoma,” “HHV-8,” “immunocompetent,” “COVID-19,” “SARS-CoV-2,” and “steroids.” No time or language limitation was set. Titles and abstracts of selected articles were systematically screened. Articles were included in the examination if they were published under free access through the digital library of the University of Brescia (Italy), and provided full text. Articles were excluded if the topic was beyond the aim of our study. Finally, we selected 15 articles.

Results

We describe a case of KS in COVID-19 patient and postulate that Interleukin-6 (IL-6) activity and steroid-induced immunodeficiency may play a major role in KS emergence. No published case of disseminated KS following COVID-19 in otherwise healthy individuals was found through the systematic literature review, despite the high incidence of COVID-19 in areas with medium–high prevalence of HHV-8 infection. This observation might be explained by the role of individual genetic susceptibility factors.

Conclusions

SARS-CoV-2 infection and its treatment may lead to reactivation of several latent infections, including HHV-8 and its related clinical syndrome, Kaposi sarcoma.

CRISPR-Cas9 Mediated Exonic Disruption for HIV-1 Elimination

BACKGROUND

A barrier to HIV-1 cure rests in the persistence of proviral DNA in infected CD4+ leukocytes. The high HIV-1 mutation rate leads to viral diversity, immune evasion, and consequent antiretroviral drug resistance. While CRISPR-spCas9 can eliminate latent proviral DNA, its efficacy is limited by HIV strain diversity and precision target cell delivery.

METHODS

A library of guide RNAs (gRNAs) designed to disrupt five HIV-1 exons (tat1-2/rev1-2/gp41) was constructed. The gRNAs were derived from a conseensus sequence of the transcriptional regulator tat from 4004 HIV-1 strains. Efficacy was affirmed by gRNA cell entry through transfection, electroporation, or by lentivirus or lipid nanoparticle (LNP) delivery. Treated cells were evaluated for viral excision by monitoring HIV-1 DNA, RNA, protein, and progeny virus levels.

FINDINGS

Virus was reduced in all transmitted founder strains by 82 and 94% after CRISPR TatDE transfection or lentivirus treatments, respectively. No recorded off-target cleavages were detected. Electroporation of TatDE ribonucleoprotein and delivery of LNP TatDE gRNA and spCas9 mRNA to latently infected cells resulted in up to 100% viral excision. Protection against HIV-1-challenge or induction of virus during latent infection, in primary or transformed CD4+ T cells or monocytes was achieved. We propose that multi-exon gRNA TatDE disruption delivered by LNPs enables translation for animal and human testing.

INTERPRETATION

These results provide "proof of concept' for CRISPR gRNA treatments for HIV-1 elimination. The absence of full-length viral DNA by LNP delivery paired with undetectable off-target affirms the importance of payload delivery for effective viral gene editing.

FUNDING

The work was supported by the University of Nebraska Foundation, including donations from the Carol Swarts, M.D. Emerging Neuroscience Research Laboratory, the Margaret R. Larson Professorship, and individual donor support from the Frances and Louie Blumkin Foundation and from Harriet Singer. The research received support from National Institutes of Health grants T32 NS105594, 5R01MH121402, 1R01Al158160, R01 DA054535, PO1 DA028555, R01 NS126089, R01 NS36126, PO1 MH64570, P30 MH062261, and 2R01 NS034239.

Reactivation of latent infections in solid organ transplant recipients from sub-Saharan Africa: What should be remembered?

International migration from Sub-Saharan African countries to the European Union and the United States has significantly increased over the past decades. Although the vast majority of these immigrants are young and healthy people, a minority can be affected by chronic conditions eventually leading to solid organ transplantation (SOT). Importantly, these candidates can bear geographically restricted fungal and parasitic latent infections that can reactivate after the procedure. An appropriate evaluation before transplantation followed by treatment, whenever necessary, is essential to minimize such risk, as covered in the present review. In short, infection due to helminths (Schistosoma spp. and Strongyloides stercoralis) and intestinal protozoa (Entamoeba histolytica, Giardia lamblia or Cyclospora cayetanensis) can be diagnosed by multiple direct stool examination, serological assays and stool antigen testing. Leishmaniasis can be assessed by means of serology, followed by nucleic acid amplification testing (NAAT) if the former test is positive. Submicroscopic malaria should be ruled out by NAAT. Screening for Histoplasma spp. or Cryptococcus spp. is not routinely indicated. Consultation with an Infectious Diseases specialist is recommended in order to adjust preemptive treatment among Sub-Saharan African SOT candidates and recipients.

Intratracheal inoculation of human varicella zoster virus (VZV; MAV strain) vaccine successfully induced VZV IgG antibodies in rhesus monkeys

BACKGROUND

The objective of this study was to investigate whether the use of live attenuated varicella zoster virus (VZV) MAV vaccination can efficiently induce VZV antibody production in naive rhesus monkeys as an approach to prevent simian varicella virus (SVV) reactivation in animals immunosuppressed for transplantation studies.

RESULTS

Clinically available human VZV vaccine was used to induce the production of anti-VZV antibodies in rhesus monkeys. A vial of the vaccine was subcutaneously injected at 0 week, and the second and third vaccination was performed at 5 and 6 weeks by intratracheal inoculation. The titer of anti-VZV IgG was assessed at 0, 2, 4, 6, and 7 weeks. At 2 weeks, 3/16 were seropositive for VZV IgG. At 6 weeks, 9/16 were shown to be seropositive. At 7 weeks, 16/16 were found to be seropositive.

CONCLUSIONS

The VZV vaccine via intratrachael inoculation was shown to induce VZV IgG humoral immunity in rhesus monkeys and may be important immunosuppressed macaques for transplantation studies. Although the humoral immunity produced is an important finding, further studies will be necessary to confirm possible protection and it could protect probably against SVV infection in rhesus monkey.

Efficient Agrobacterium tumefaciens-mediated transformation system of Diaporthe caulivora

This is the first report describing the genetic transformation of Diaporthe caulivora, the soybean stem canker fungus. A simple and 100% efficient protocol of Agrobacterium tumefaciens-mediated transformation used mycelium as starting material and the hygromycin B resistance and green fluorescent protein (GFP) as a selection and reporter agents, respectively. All transgenic isolates were mitotically stable in two independent experiments and polymerase chain reaction with hygromycin B resistance primers confirmed successful T-DNA integration into the fungal genome. Plant-fungus interaction studies, including pathogenicity, latency, and endophytism, as well as further studies of random and targeted mutagenesis will be possible with GFP-expressing isolates of D. caulivora and other species in the Diaporthe / Phomopsis complex.

How Does HIV Persist Under Antiretroviral Therapy: A Review of the Evidence

HIV-1 is a retrovirus capable of establishing viral reservoirs that remain stable for extended periods under suppressive antiretroviral therapy (ART). Immune dysfunction and latency are well known to contribute to this longevity, but the respective roles of viral replication and latently infected (LI) cell proliferation under suppressive antiretroviral therapy (ART) have long been controversial. This historical review critically appraises the body of evidence regarding possible viral replication and proliferation of infected cells under ART. An ever-growing body of genetic and phylogenetic studies has demonstrated that HIV-infected cells are able to proliferate and contribute to the longevity of the reservoir in ART-treated patients. The role of ongoing replication remains controversial: it has been well established that HIV does not undergo evolution during ART or develop drug resistance, but some genetic, phylogenetic, and in vivo imaging studies have suggested that there may be ongoing replication despite this. The respective roles of viral replication and cellular proliferation in maintaining the LI reservoir remains an area of controversy. Elucidating these processes may allow us design interventions to reduce the size of the LI reservoir, increasing the length of treatment interruptions during which the virus will remain adequately suppressed, bringing us closer to a functional cure. Novel experimental techniques such as immuno-PET and digital droplet PCR (ddPCR) are increasingly being employed, and these, along with rapid particle sorting techniques currently in develop-ment, will be necessary to fully answer this question.

Efficient establishment of reactivatable latency by an acyclovir-resistant herpes simplex virus 1 thymidine kinase substitution mutant with reduced neuronal replication

Herpes simplex virus 1 causes recurrent diseases by reactivating from latency, which requires the viral thymidine kinase (TK) gene. An acyclovir-resistant mutation in TK, V204G, was previously repeatedly identified in a patient with recurrent herpetic keratitis. We found that compared with its parental strain KOS, a laboratory-derived V204G mutant virus was impaired in replication in cultured neurons despite little defect in non-neuronal cells. After corneal inoculation of mice, V204G exhibited defects in ocular replication that were modest over the first three days but severe afterward. Acute replication of V204G in trigeminal ganglia was significantly impaired. However, V204G established latency with viral loads as high as KOS and reactivated with high frequency albeit reduced kinetics. Acyclovir treatment that drastically decreased ocular and ganglionic replication of KOS had little effect on V204G. Thus, despite reduced neuronal replication due to impaired TK activity, this clinically relevant drug-resistant mutant can efficiently establish reactivatable latency.

CRISPR based genome editing and removal of human viruses

The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated proteins 9 (Cas9), a gene-editing technology, has been extensively applied as a tool for genetic engineering in basic research. Efficient genome engineering has been performed in viruses, human cells, bacteria, fungi, plants and animals, etc. Currently, it has been employed to edit human viruses for studying viral molecular biology, pathogenesis and oncogenesis, and facilitate the development of antiviral agents and vaccine. The virus is ubiquitous worldwide and elicits global health problems, many human diseases are associated with virus infections. Although traditional drugs can be used to treat or prevent productive viral infections, their efficacy is limited because of toxicity, side effects and other problems. Additionally, no current drugs are approved to be indicated for latent infections. Therefore, the next highlight is to develop antiviral approaches to against both productive and latent infections. Fortunately, CRISPR has been successfully applied in the removal of human viruses ex vivo and/or in vivo, and has the potential to be used to manufacture antiviral agents for clinical application. CRISPR/Cas9 is promising in applications, even though some technical challenges, safety concerns, ethic concerns need to be improved. In this article, the discovery and application of genome editing and removal of human viruses based on CRISPR are explored. Additionally, we evaluate the prospects and limitations of this novel antiviral strategies.

Induction of E. coli-derived endonuclease MazF suppresses HIV-1 production and causes apoptosis in latently infected cells

The current antiretroviral therapy cannot cure the patients infected with human immunodeficiency virus type 1 (HIV-1) due to the existence of latently infected cells capable of virus production from harboring proviral DNA. MazF is an ACA nucleotide sequence-specific endoribonuclease derived from Escherichia coli. The conditional expression of MazF by binding of HIV-1 Tat to the promoter region of a MazF-expression vector has previously been shown to selectively inhibit HIV-1 replication in acutely infected cells. The expression of MazF significantly suppressed tumor necrosis factor (TNF)-α-induced HIV-1 production and viral RNA expression in the HIV-1 latently infected cell line OM-10.1 transduced with the MazF-expression vector (OM-10.1/MFR). Moreover, the viability of OM-10.1/MFR cells decreased with increasing concentrations of TNF-α, whereas such decrease was not observed for HL-60 cells transduced with the MazF-expression vector (HL-60/MFR), the uninfected parental cell line of OM-10.1. TNF-α increased the expression of cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase in OM-10.1/MFR cells, indicating that the cell death was caused by the induction of apoptosis. TNF-α-induced expression of MazF mRNA was detected in OM-10.1/MFR but not HL-60/MFR cells, suggesting that TNF-α-induced apoptosis of latently infected cells was due to the expression of MazF. Thus, the anti-HIV-1 gene therapy using the MazF-expression vector may have potential for the cure of HIV-1 infection in combination with suitable latency reversing agents through reducing the size of latently infected cells without viral reactivation.

What's New in Feline Leukemia Virus Infection

Feline leukemia virus (FeLV) is a retrovirus with global impact on the health of domestic cats that causes tumors (mainly lymphoma), bone marrow disorders, and immunosuppression. The importance of FeLV is underestimated due to complacency associated with previous decline in prevalence. However, with this comes lowered vigilance, which, along with potential for regressively infected cats to reactivate viremia and shed the virus or develop clinical signs, can pose a risk to feline health. This article summarizes knowledge on FeLV pathogenesis, courses of infection, and factors affecting prevalance, infection outcome, and development of FeLV-associated diseases, with special focus on regressive FeLV infection.

MicroRNAs expressed by human cytomegalovirus

Background

MicroRNAs (miRNAs) are small non-coding RNAs about 22 nucleotides in length, which play an important role in gene regulation of both eukaryotes and viruses. They can promote RNA cleavage and repress translation via base-pairing with complementary sequences within mRNA molecules.

Main body

Human cytomegalovirus (HCMV) encodes a large number of miRNAs that regulate transcriptions of both host cells and themselves to favor viral infection and inhibit the host’s immune response. To date, ~ 26 mature HCMV miRNAs have been identified. Nevertheless, their roles in viral infection are ambiguous, and the mechanisms have not been fully revealed. Therefore, we discuss the methods used in HCMV miRNA research and summarize the important roles of HCMV miRNAs and their potential mechanisms in infection.

Conclusions

To study the miRNAs encoded by viruses and their roles in viral replication, expression, and infection will not only contribute to the planning of effective antiviral therapies, but also provide new molecular targets for the development of antiviral drugs.

Examination of the fecal microbiota in dairy cows infected with bovine leukemia virus

Infection of cattle by bovine leukemia virus (BLV) causes significant economic losses in terms of milk and meat production in many countries. Because the gut microbiota may be altered by immunomodulation resulting from viral infections, we hypothesized that latent BLV infection would change the gut (i.e., rumen and hindgut) microbiota of infected cattle. In this study, we compared the gut microbiota of 22 uninfected and 29 BLV-infected Holstein-Friesian cows kept on the same farm, by 16S rRNA amplicon sequence analysis of fecal samples. First, we found that the fecal microbial diversity of BLV-infected cows differed slightly from that of uninfected cows. According to differential abundance analysis, some bacterial taxa associated with ruminal fermentation, such as Lachnospiraceae and Veillonellaceae families, were enriched in the fecal microbiota of uninfected cows. Second, the virus propagation ability of BLV strains was examined in vitro, and the correlation of the fecal microbiota with this virus propagation ability was analyzed. Higher virus propagation was shown to lead to less diversity in the microbiota. Differential abundance analysis showed that one bacterial taxon of genus Sanguibacteroides was negatively correlated with the virus propagation ability of BLV strains. Considering these results, BLV infection was speculated to decrease energy production efficiency in the cows via modification of rumen and hindgut microbiota, which partly relies on the virus propagation ability of BLV strains. This may explain the secondary negative effects of BLV infections such as increased susceptibility to other infections and decreased lifetime milk production and reproductive efficiency.

Heterogeneity in HIV and cellular transcription profiles in cell line models of latent and productive infection: implications for HIV latency

Background

HIV-infected cell lines are widely used to study latent HIV infection, which is considered the main barrier to HIV cure. We hypothesized that these cell lines differ from each other and from cells from HIV-infected individuals in the mechanisms underlying latency.

Results

To quantify the degree to which HIV expression is inhibited by blocks at different stages of HIV transcription, we employed a recently-described panel of RT-ddPCR assays to measure levels of 7 HIV transcripts (“read-through,” initiated, 5′ elongated, mid-transcribed/unspliced [Pol], distal-transcribed [Nef], polyadenylated, and multiply-sliced [Tat-Rev]) in bulk populations of latently-infected (U1, ACH-2, J-Lat) and productively-infected (8E5, activated J-Lat) cell lines. To assess single-cell variation and investigate cellular genes associated with HIV transcriptional blocks, we developed a novel multiplex qPCR panel and quantified single cell levels of 7 HIV targets and 89 cellular transcripts in latently- and productively-infected cell lines. The bulk cell HIV transcription profile differed dramatically between cell lines and cells from ART-suppressed individuals. Compared to cells from ART-suppressed individuals, latent cell lines showed lower levels of HIV transcriptional initiation and higher levels of polyadenylation and splicing. ACH-2 and J-Lat cells showed different forms of transcriptional interference, while U1 cells showed a block to elongation. Single-cell studies revealed marked variation between/within cell lines in expression of HIV transcripts, T cell phenotypic markers, antiviral factors, and genes implicated in latency. Expression of multiply-spliced HIV Tat-Rev was associated with expression of cellular genes involved in activation, tissue retention, T cell transcription, and apoptosis/survival.

Conclusions

HIV-infected cell lines differ from each other and from cells from ART-treated individuals in the mechanisms governing latent HIV infection. These differences in viral and cellular gene expression must be considered when gauging the suitability of a given cell line for future research on HIV. At the same time, some features were shared across cell lines, such as low expression of antiviral defense genes and a relationship between productive infection and genes involved in survival. These features may contribute to HIV latency or persistence in vivo, and deserve further study using novel single cell assays such as those described in this manuscript.

Antigenic relationships between Caprine alphaherpesvirus 1 (CpHV-1) and Bovine alphaherpesvirus 1 (BoHV-1) and experimental CpHV-1 infection of kids and calves

Caprine alphaherpesvirus 1 (CpHV-1) is a worldwide pathogen of goats and is closely related to Bovine alphaherpevirus 1 (BoHV-1). We herein studied the antigenic relationships of CpHV-1 with BoHV-1 and investigated the pathogenesis of CpHV-1 in kids and calves. Monoclonal antibody reactivity revealed that CpHV-1 and BoHV-1 share immunogenic epitopes in the major envelope glycoproteins gB, gC and gD. The antigenic relationship was further demonstrated by virus-neutralizing assays, in which CpHV-1 and BoHV-1 antisera presented varied degrees of cross-neutralization against the respective heterologous viruses. Although cross-neutralization was observed between both viruses and the heterologous antisera, BoHV-1 antisera neutralized CpHV-1 with higher efficiency than CpHV-1 antisera neutralized BoHV-1. Hence, the antigenic cross-reactivity between CpHV-1 and BoHV-1 should be considered upon serologic testing of goats and cattle in regions where the two viruses co-circulate. Intranasal (IN) inoculation of CpHV-1 (WI13-46 isolate) in seven seronegative kids resulted in efficient viral replication in the respiratory tract. Additionally, mild to moderate systemic and respiratory signs were observed, including apathy, hyperthermia, nasal discharge and respiratory distress. Dexamethasone administration to the inoculated kids between days 36 and 40 pi did not result in virus shedding in nasal secretions. However, latent infection had been established, as evidenced by the detection of CpHV-1 DNA in trigeminal ganglia and olfactory bulbs of kids euthanized at day 67 pi. Contrasting with the outcome of infection in kids, IN inoculation of CpHV-1 in calves did not result in productive infection as no virus replication or shedding were detected, and the animals did not develop clinical signs nor seroconverted. The animal experiments demonstrated that CpHV-1 was able to produce respiratory disease in kids, but did not replicate to detectable levels in calves.

Isolation and identification of bubaline herpesvirus 1 (BuHV-1) from latently infected water buffalo (Bubalus bubalis) from Iran

In order to isolate buffaloes herpesvirus 1 (BuHV-1) from latently infected water buffalo (Bubalus bubalis), 16 buffalo heifers were selected from a herd. At first, animals were bled and their sera were tested by virus neutralization (VN) test, using bovine herpesvirus 1 (BoHV-1). According to the results of VN test and dexamethasone injection (0.1 mg/kg BW) for 5 consecutive days, the examined buffaloes were divided into 4 groups. Vaginal and nasal swabs were daily collected from all buffaloes from day 0 to 10 days later. Based on the cytopathic effects in cell culture, a herpesvirus was isolated only from nasal swabs of three seropositive buffaloes which they had received dexamethasone. The nasal swabs of these three buffaloes were also positive in PCR, using primers specific for ruminant herpesviruses gD gene. The identity of the isolated viruses was determined according to partial amino acid sequences of gD, deduced from the nucleotide sequences of the PCR products. On the basis of sequence alignment, phylogenetic analysis, and genetic distances, the three buffalo virus isolates were more closely related to BuHV-1 and BoHV-5 than to BoHV-1.

Pediatric roots of cytomegalovirus recurrence and memory inflation in the elderly

The establishment of a lifelong latent infection after resolution of primary infection is a hallmark of cytomegalovirus (CMV) biology. Primary infection with human CMV is possible any time in life, but most frequently, virus transmission occurs already perinatally or in early childhood. Many years or even decades later, severe clinical problems can result from recurrence of infectious virus by reactivation from latency in individuals who undergo immunocompromising medical treatment, for instance, transplant recipients, but also in septic patients without canonical immunosuppression, and in elderly people with a weakened immune system. The diversity of disease manifestations, such as retinitis, pneumonia, hepatitis, gastrointestinal disease, and others, has remained an enigma. In clinical routine, seropositivity for IgG antibodies against human CMV is taken to indicate latent infection and thus to define a qualitative risk of recurrence, but it is insufficient as a predictor for the quantitative risk of recurrence. Early experimental studies in the mouse model, comparing primary infection of neonatal and adult mice, led to the hypothesis that high load of latent viral genomes is a better predictor for the quantitative risk. A prolonged period of virus multiplication in the immunologically immature neonatally infected host increased the risk of virus recurrence by an enhanced copy number of latent virus genomes from which reactivation can initiate. In extension of this hypothesis, one would predict today that a higher incidence of reactivation events will also fuel the expansion of virus-specific T cells observed in the elderly, a phenomenon known as "memory inflation". Notably, the mouse model also indicated a stochastic nature of reactivation, thus offering an explanation for the diversity and organ selectivity of disease manifestations observed in patients. As the infection history is mostly undefined in humans, such predictions from the mouse model are difficult to verify by clinical investigation, and moreover, such questions were actually rarely addressed. Here, we have surveyed the existing literature for reports that may help to retrospectively relate the individual infection history to the risk of virus recurrence and recrudescent organ disease.

Transcripts expressed in cytomegalovirus latency coding for an antigenic IE/E phase peptide that drives "memory inflation"

Roizman's definition of herpesviral latency, which applies also to cytomegaloviruses (CMVs), demands maintenance of reactivation-competent viral genomes after clearance of productive infection. It is more recent understanding that failure to complete the productive viral cycle for virus assembly and release does not imply viral gene silencing at all genetic loci and all the time. It rather appears that CMV latency is transcriptionally "noisy" in that silenced viral genes get desilenced from time to time in a stochastic manner, leading to "transcripts expressed in latency" (TELs). If a TEL happens to code for a protein that contains a CD8 T cell epitope, protein processing can lead to the presentation of the antigenic peptide and restimulation of cognate CD8 T cells during latency. This mechanism is discussed as a potential driver of epitope-selective accumulation of CD8 T cells over time, a phenomenon linked to CMV latency and known as "memory inflation" (MI). So far, expression of an epitope-encoding TEL was shown only for the major immediate-early (MIE) gene m123/ie1 of murine cytomegalovirus (mCMV), which codes for the prototypic MI-driving antigenic peptide YPHFMPTNL that is presented by the MHC class-I molecule L^d. The only known second MI-driving antigenic peptide of mCMV in the murine MHC haplotype H-2^d is AGPPRYSRI presented by the MHC-I molecule D^d. This peptide is very special in that it is encoded by the early (E) phase gene m164 and by an overlapping immediate-early (IE) transcript governed by a promoter upstream of m164. If MI is driven by presentation of TEL-derived antigenic peptides, as the hypothesis says, one should find corresponding TELs. We show here that E-phase and IE-phase transcripts that code for the MI-driving antigenic peptide AGPPRYSRI are independently and stochastically expressed in latently infected lungs.

Tuberculosis in Children

Mycobacterium tuberculosis is the leading cause of death worldwide from a single bacterial pathogen. The World Health Organization estimates that annually 1 million children have tuberculosis (TB) disease and many more harbor a latent form. Accurate estimates are hindered by under-recognition and challenges in diagnosis. To date, an accurate diagnostic test to confirm TB in children does not exist. Treatment is lengthy but outcomes are generally favorable with timely initiation. With the End TB Strategy, there is an urgent need for improved diagnostics and treatment to prevent the unnecessary morbidity and mortality from TB in children.

Molecular Biology of EBV in Relationship to HIV/AIDS-Associated Oncogenesis

Herpesvirus-induced disease is one of the most lethal factors which leads to high mortality in HIV/AIDS patients. EBV, also known as human herpesvirus 4, can transform naive B cells into immortalized cells in vitro through the regulation of cell cycle, cell proliferation, and apoptosis. EBV infection is associated with several lymphoma and epithelial cancers in humans, which occurs at a much higher rate in immune deficient individuals than in healthy people, demonstrating that the immune system plays a vital role in inhibiting EBV activities. EBV latency infection proteins can mimic suppression cytokines or upregulate PD-1 on B cells to repress the cytotoxic T cells response. Many malignancies, including Hodgkin Lymphoma and non-Hodgkin's lymphomas occur at a much higher frequency in EBV positive individuals than in EBV negative people during the development of HIV infection. Importantly, understanding EBV pathogenesis at the molecular level will aid the development of novel therapies for EBV-induced diseases in HIV/AIDS patients.

Detection of koi herpesvirus in healthy common carps, Cyprinus carpio L

Koi herpesvirus (KHV), a member of Hervesviridae, has been frequently reported to cause mass mortality (80-100%) in common carps (Cyprinus carpio L.). A unique feature of Herverviridae members is latent infection, maintaining their genetic information for an extended period in the absence of productive infection, and reactivate when environmental conditions are favorable for their growth. To prevent this occurs, a monitoring program should be done for early detection. This study aimed at detecting the presence of KHV in healthy common carps reared in West-Nusa Tenggara Province, Indonesia. A total of 80 healthy fish was collected randomly from eight fish farms (Lingsar, Batu Kumbung, Narmada, Tanjung, Lenek, Aik Mel, Brang Rea and Rhee) across West-Nusa Tenggara Province, Indonesia. The presence of KHV genome was detected using a PCR with a commercial kit, IQ 2000TM. The result showed that common carps collected from four farms (Aik Mel, Lenek, Rhee and Brang Rea) were positive KHV. The size of an amplified gene was ~ 550 bp which was the same as positive KHV control. The obtained result suggests that KHV as other member of Hervesviridae shows a latent infection in common carps, and should be anticipated for their reactivation. Based on this result it is highly recommended that common carps cultured in this region should be vaccinated. In addition, transporting common carp out from Lombok and Sumbawa Islands should be carefully regulated to prevent the spread of the disease to other areas.

Lymphatic endothelial cells promote productive and latent HIV infection in resting CD4+ T cells

Background

An HIV cure has not yet been achieved because latent viral reservoirs persist, particularly in resting CD4+ T lymphocytes. In vitro, it is difficult to infect resting CD4+ T cells with HIV-1, but infections readily occur in vivo. Endothelial cells (EC) line the lymphatic vessels in the lymphoid tissues and regularly interact with resting CD4+ T cells in vivo. Others and we have shown that EC promoted productive and latent HIV infection of resting CD4+ T cells. However, the EC used in previous studies were from human umbilical cords (HUVEC), which are macrovascular; whereas EC residing in the lymphoid tissues are microvascular.

Methods

In this study, we investigated the effects of microvascular EC stimulation of resting CD4+ T cells in establishing viral infection and latency. Human resting and activated CD4+ T cells were cultured alone or with endothelial cells and infected with a pseudotyped virus. Infection levels, indicated by green fluorescent protein expression, were measured with flow cytometry and data was analyzed using Flowing Software and Excel.

Results

We confirmed that EC from lymphatic tissue (LEC) were able to promote HIV infection and latency formation in resting CD4+ T cells while keeping them in resting phenotype, and that IL-6 was involved in LEC stimulation of CD4+ T cells. However, there are some differences between stimulation by LEC and HUVEC. Unlike HUVEC stimulation, we demonstrated that LEC stimulation of resting memory T cells does not depend on major histocompatibility complex class II (MHC II) interactions with T cell receptors (TCR) and that CD2-CD58 interactions were not involved in LEC stimulation of resting T cells. LEC also secreted lower levels of IL-6 than HUVEC. We also found that LEC stimulation increases HIV infection rates in activated CD4+ T cells.

Conclusions

While differences in T cell stimulation between lymphatic EC and HUVEC were observed, we confirmed that similar to macrovascular EC stimulation, microvascular EC stimulation promotes direct HIV infection and latency formation in resting CD4+ T cells without T cell activation. LEC stimulation also increased infection rates in activated CD4+ T cells. Additionally, the present study established a physiologically more relevant model of EC interactions with resting CD4+ T cells and further highlighted the importance of investigating the roles of EC in HIV infection and latency in both resting and activated CD4+ T cells.

Environmental stressors may cause equine herpesvirus reactivation in captive Grévy's zebras (Equus grevyi)

Equine Herpesviruses (EHV) are common and often latent pathogens of equids which can cause fatalities when transmitted to non-equids. Stress and elevated glucocorticoids have been associated with EHV reactivation in domestic horses, but little is known about the correlation between stress and viral reactivation in wild equids. We investigated the effect of an environmental stressor (social group restructuring following a translocation event) on EHV reactivation in captive Grévy's zebras (Equus grevyi). A mare was translocated by road transport from Zoo Mulhouse, France, to join a resident group of three mares in Tierpark Berlin, Germany. We used an indirect sampling method to assess the frequency of EHV shedding for 14 days immediately after the translocation event (termed the 'experimental period'). The results were compared with those from two control periods, one preceding and one subsequent to the experimental period. In addition, we measured fecal glucocorticoid metabolite (fGCM) concentrations daily in all individuals from 6 days before, to 14 days after translocation. We found significantly higher EHV shedding frequencies during the experimental period, compared to each of the two control periods. All animals showed significantly elevated fGCM concentrations, compared to fGCM levels before translocation. Finally, we found that an increase in fGCM concentration was significantly associated with an increased likelihood of EHV shedding. Although the small number of animals in the study limits the conclusions that can be drawn from the study, taken together, our results support the hypothesis that environmental stressors induce viral reactivation in wild equids. Our results suggest that potentials stressors such as group restructuring and translocation should be considered in the management of zoological collections to reduce the risk of fatal EHV infections in novel hosts. Moreover, environmental stressors may play an important role in EHV reactivation and spread in wild equid populations.

Selection of biomarkers for HIV-1 latency by integrated analysis

A major obstacle in the treatment of human immunodeficiency virus type 1 (HIV-1) is its ability to establish latent infection. To find novel biomarkers associated with the mechanism of HIV-1 latent infection, we identified 70 candidate genes in HIV-1 latently infected cells through the integrated analysis in a previous study. It is important to select more effective biomarkers among 70 candidates and to verify the possibility of selected biomarkers for HIV-1 latency. We identified the 24 and 25 genes from 70 candidate genes in significantly enriched categories selected by Database for Annotation, Visualization and Integrated Discovery (DAVID) software and Gene Set Enrichment Analysis (GSEA) software, respectively. Also, we investigated genes regulated in both HIV-1 latently infected cell lines and PBMCs from HIV-1 infected patients and found the genes with a common pattern of expression levels in both cell lines and PBMCs. Consequently, we identified nine genes, APBB2, GMPR, IGF2BP3, LRP1, MAD2L2, MX1, OXR1, PTK2B, and TNFSF13B, via integrated analysis. Especially, APBB2 and MAD2L2 were identified in both DAVID and GSEA software. Our findings suggest that nine genes were identified via integrated analysis as potential biomarkers and in particular, APBB2 and MAD2L2 may be considered as more significant biomarkers for HIV-1 latency.

Evaluation of Mycobacterium tuberculosis-specific antibody responses for the discrimination of active and latent tuberculosis infection

OBJECTIVES

The serological antibody detection tests offer several advantages for the rapid diagnosis of tuberculosis (TB). The Mycobacterium tuberculosis-specific antibody responses associated with different stages of TB infection remain to be investigated.

METHODS

The Pathozyme-Myco IgG (Myco G), Pathozyme TB Complex Plus (TB Complex), IBL M. tuberculosis IgG ELISA (IBL), Anda Biologicals TB IgG (Anda-TB), and T-SPOT.TB (T-SPOT) tests were performed for 133 active TB patients (ATB group), 131 controls (CON group), and 95 subjects with latent TB infection (LTBI group).

RESULTS

The four serological tests all showed relatively low sensitivity in the ATB group but high specificity in the LTBI and CON groups. The antibody levels of the four serological tests were significantly higher in the ATB group than in the LTBI group. The same trend was observed between the LTBI and CON groups. The four serological tests demonstrated potential diagnostic value in discriminating ATB from LTBI. A combination of the Anda-TB and TB Complex tests exhibited the best diagnostic potential in discriminating ATB from LTBI, with a sensitivity of 89.4% and a specificity of 94.7%. Further, the diagnostic value of Anda-TB and TB Complex were validated in a prospective cohort including 106 patients with suspected ATB. Combined with the T-SPOT test, the tests showed a sensitivity of 87.2% and a specificity of 92.5% for discriminating ATB patients from all ATB suspected cases in the validation group.

CONCLUSIONS

The antibody responses of the serological tests all showed significant differences between the ATB and LTBI groups. A combination of Anda-TB and the TB Complex test demonstrated high diagnostic potential in discriminating ATB from LTBI and may be an additional diagnostic tool in the diagnosis of M. tuberculosis infection.

Observations on bradyzoite biology

Tachyzoites of the Apicomplexan Toxoplasma gondii cause acute infection, disseminate widely in their host, and eventually differentiate into a latent encysted form called bradyzoites that are found within tissue cysts. During latent infection, whenever transformation to tachyzoites occurs, any tachyzoites that develop are removed by the immune system. In contrast, cysts containing bradyzoites are sequestered from the immune system. In the absence of an effective immune response released organisms that differentiate into tachyzoites cause acute infection. Tissue cysts, therefore, serve as a reservoir for the reactivation of toxoplasmosis when the host becomes immunocompromised by conditions such as HIV infection, organ transplantation, or due to the impaired immune response that occurs when pathogens are acquired in utero. While tachyzoites and bradyzoites are well defined morphologically, there is no clear consensus on how interconversion occurs or what exact signal(s) mediate this transformation. Advances in research methods have facilitated studies on T. gondii bradyzoites providing important new insights into the biology of latent infection.

Gene expression profiling of the TRIM protein family reveals potential biomarkers for indicating tuberculosis status

Tripartite motif (TRIM) family proteins play important regulatory roles in innate immune responses, the dysregulation of which cause several infectious diseases. However, the role and function of TRIM family proteins during tuberculosis (TB) infection remains unclear. In this study, we employed real-time quantitative PCR to profile the transcript levels of 72 TRIM genes from a cohort of 5 active TB patients, 5 latent tuberculosis infection (LTBI) subjects, and 5 healthy controls (HCs) in an initial discovery phase. The notable TRIM genes were assessed by in vitro cell infection experiments and further validated in another independent cohort (36 active TB, 24 LTBI and 28 HCs). The receiver operating characteristic (ROC) was used to analyze the diagnostic power of these TRIM genes. Our results revealed that 20 TRIM genes were decreased in active TB compared to LTBI and HCs. In addition, TRIM4, 16, 27, 32, 35, 46, 47, 65 and 68 were further shown to be downregulated in Mycobacterium smegmatis-infected macrophages and were found to be closely correlated with infection time and initial bacteria loads. Furthermore, the ROC analyses showed that TRIM4, 27 and 65 all exhibited the highest areas under the curve (AUC) values of 1.00 in discriminating active TB from LTBI and HCs. Moreover, TRIM27 combined with TRIM32 for an improved AUC value of 0.81 in discriminating LTBI from HCs. These results suggest that TRIM gene dysregulation might be involved in the pathogenesis of TB and that these genes could serve as potential biomarkers for indicating TB status.

Toxoplasma gondii-positive human sera recognise intracellular tachyzoites and bradyzoites with diverse patterns of immunoreactivity

Antibody detection assays have long been the first line test to confirm infection with the zoonotic parasite Toxoplasma gondii. However, challenges exist with serological diagnosis, especially distinguishing between acute, latent and reactivation disease states. The sensitivity and specificity of serological tests might be improved by testing for antibodies against parasite antigens other than those typically found on the parasite surface during the acute stage. To this end, we analysed the reactivity profile of human sera, identified as positive for anti-Toxoplasma gondii IgG in traditional assays, by indirect immunofluorescence reactivity to acute stage intracellular tachyzoites and in vitro-induced latent stage bradyzoites. The majority of anti-Toxoplasma gondii IgG positive sera recognised both intracellularly replicating tachyzoites and in vitro-induced bradyzoites with varying patterns of immune-reactivity. Furthermore, anti-bradyzoite antibodies were not detected in sera that were IgM-positive/IgG-negative. These results demonstrate that anti-Toxoplasma gondii-positive sera may contain antibodies to a variety of antigens in addition to those traditionally used in serological tests, and suggest the need for further investigations into the utility of anti-bradyzoite-specific antibodies to aid in diagnosis of Toxoplasma gondii infection.

Tuberculosis in Children

Mycobacterium tuberculosis is the leading cause of death worldwide from a single bacterial pathogen. The World Health Organization estimates that annually 1 million children have tuberculosis (TB) disease and many more harbor a latent form. Accurate estimates are hindered by under-recognition and challenges in diagnosis. To date, an accurate diagnostic test to confirm TB in children does not exist. Treatment is lengthy but outcomes are generally favorable with timely initiation. With the End TB Strategy, there is an urgent need for improved diagnostics and treatment to prevent the unnecessary morbidity and mortality from TB in children.

Infected T98G glioblastoma cells support human cytomegalovirus reactivation from latency

T98G cells have been shown to support long-term human cytomegalovirus (HCMV) genome maintenance without infectious virus release. However, it remains unclear whether these viral genomes could be reactivated. To address this question, a recombinant HCMV (rHCMV) containing a GFP gene was used to infect T98G cells, and the infected cells absent of infectious virus production were designated T98G-LrV. Upon dibutyryl cAMP plus IBMX (cAMP/IBMX) treatment, a serial of phenomena were observed, including GFP signal increase, viral genome replication, lytic genes expression and infectious viruses release, indicating the reactivation of HCMV in T98G-LrV cells from a latent status. Mechanistically, HCMV reactivation in the T98G-LrV cells induced by cAMP/IBMX was associated with the PKA-CREB signaling pathway. These results demonstrate that HCMV was latent in T98G-LrV cells and could be reactivated. The T98G-LrV cells represent an effective model for investigating the mechanisms of HCMV reactivation from latency in the context of neural cells.

[Tuberculosis treatment for children: An update]

Tuberculosis (TB) is the most important infectious disease all over the world, with a high morbidity and mortality. Pediatric tuberculosis has been a neglected epidemic, due to the difficulties in assessing its global impact, reduced incidence and lower infectivity compared to adults. In 2015, the WHO reported 1 million cases of paediatric TB and 169,000 deaths. In Europe, the emergence of MDR TB is a major concern, representing 16% of the new diagnosis in Eastern Europe. In 2014, it was estimated that about 219,000 children were infected by MDR-TB-strains in Europe, and 2,120 developed the disease. Spain is the Western European country with more paediatric cases, with an incidence 4.3/100,000 inhabitants in 2014. Paediatric tuberculosis mortality in Spain is rare, but extra-pulmonary disease is associated with significant complications. The prevalence of paediatric drug resistant TB in Spain is over 4%, higher than the estimated incidence in adult population, representing mayor difficulties for therapeutic intervention. These data reveal that paediatric TB is still a Public Health priority in our country. The difficulties in diagnosis and the lack of optimal paediatric drug formulations are the major challenges for controlling the childhood's tuberculosis epidemic. A group of national paeditric TB experts has reviewed the international guidelines and the most recent evidences, and has established new recommendations for the management of paediatric TB contacts, latent infection and active TB disease, especially focused in drug resistant cases. This document replaces the former national guidelines from the Spanish Society for Pediatric Infectios Diseases, although the prior recommendations on the diagnosis remain valid.

One-step reverse transcription loop-mediated isothermal amplification assay for detection of Apple chlorotic leaf spot virus

A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for the detection of Apple chlorotic leaf spot virus (ACLSV). In this method, a set of four primers was designed based on the conserved regions in the coat protein gene of ACLSV, and the primers were synthesized for the RT-LAMP assay using total RNA extracted from ACLSV-infected leaf tissues. The optimal reaction temperature and assay time were determined to be 64°C and 75min, respectively. The sensitivity of RT-LAMP reactions was reliable up to a maximum dilution of 1:3125, which was more sensitive than the RT-PCR assay. The successful application of RT-LAMP to field-collected apple samples demonstrated its potential for broader applications in effectively diagnosing diseases and, consequently, its potential to control ACLSV from spreading further, particularly in many developing countries around the world. To our knowledge, this is the first application of RT-LAMP for the detection of ACLSV.

A Multistage Subunit Vaccine Effectively Protects Mice Against Primary Progressive Tuberculosis, Latency and Reactivation

Adult tuberculosis (TB) is the main cause of TB epidemic and death. The infection results mainly by endogenous reactivation of latent TB infection and secondarily transmitted by exogenous infection. There is no vaccine for adult TB. To this end, we first chose antigens from a potential antigenic reservoir. The antigens strongly recognized T cells from latent and active TB infections that responded to antigens expressed by Mycobacterium tuberculosis cultured under different metabolic states. Fusions of single-stage polyprotein CTT3H, two-stage polyprotein A1D4, and multistage CMFO were constructed. C57BL/6 mice vaccinated with DMT adjuvant ed CMFO (CMFO-DMT) were protected more significantly than by CTT3H-DMT, and efficacy was similar to that of the only licensed vaccine, Bacillus Calmette–Guérin (BCG) and A1D4-DMT in the M. tuberculosis primary infection model. In the setting of BCG priming and latent TB infection, M. tuberculosis in the lung and spleen was eliminated more effectively in mice boosted with CMFO-DMT rather than with BCG, A1D4-DMT, or CTT3H-DMT. In particular, sterile immunity was only conferred by CMFO-DMT, which was associated with expedited homing of interferon-gamma⁺ CD4⁺ T_EM and interleukin-2⁺ T_CM cells from the spleen to the infected lung. CMFO-DMT represents a promising candidate to prevent the occurrence of adult TB through both prophylactic and therapeutic methods, and warrants assessment in preclinical and clinical trials.

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CMFO-DMT provides the comparable protection against primary infection with M. tuberculosis as BCG vaccine does.

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CMFO-DMT boosts an effective protection of BCG primed mice to eliminate latent infection and thwart reactivation.

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CMFO-DMT is a promising vaccine candidate for the prevention of adult TB disease.

Adult pulmonary TB is the main clinical form of the disease and the main component of TB epidemics. There is no effective vaccine to protect adults from primary and secondary TB. Vaccine candidates were constructed using combinations of one-, two- or multi-stage antigens of M. tuberculosis representing different stages of the infection. The antigen combinations directed at different stages of TB may help control adult TB.

Defining nervous system susceptibility during acute and latent herpes simplex virus-1 infection

Herpes simplex viruses are neurotropic human pathogens that infect and establish latency in peripheral sensory neurons of the host. Herpes Simplex Virus-1 (HSV-1) readily infects the facial mucosa that can result in the establishment of a latent infection in the sensory neurons of the trigeminal ganglia (TG). From latency, HSV-1 can reactivate and cause peripheral pathology following anterograde trafficking from sensory neurons. Under rare circumstances, HSV-1 can migrate into the central nervous system (CNS) and cause Herpes Simplex Encephalitis (HSE), a devastating disease of the CNS. It is unclear whether HSE is the result of viral reactivation within the TG, from direct primary infection of the olfactory mucosa, or from other infected CNS neurons. Areas of the brain that are susceptible to HSV-1 during acute infection are ill-defined. Furthermore, whether the CNS is a true reservoir of viral latency following clearance of virus during acute infection is unknown. In this context, this review will identify sites within the brain that are susceptible to acute infection and harbor latent virus. In addition, we will also address findings of HSV-1 lytic gene expression during latency and comment on the pathophysiological consequences HSV-1 infection may have on long-term neurologic performance in animal models and humans.

Current Progress in EBV-Associated B-Cell Lymphomas

Epstein-Barr virus (EBV) was the first human tumor virus discovered more than 50 years ago. EBV-associated lymphomagenesis is still a significant viral-associated disease as it involves a diverse range of pathologies, especially B-cell lymphomas. Recent development of high-throughput next-generation sequencing technologies and in vivo mouse models have significantly promoted our understanding of the fundamental molecular mechanisms which drive these cancers and allowed for the development of therapeutic intervention strategies. This review will highlight the current advances in EBV-associated B-cell lymphomas, focusing on transcriptional regulation, chromosome aberrations, in vivo studies of EBV-mediated lymphomagenesis, as well as the treatment strategies to target viral-associated lymphomas.