The enteric pathogen Cryptosporidium parvum exports proteins into the cytosol of the infected host cell

The parasite Cryptosporidium is responsible for diarrheal disease in young children causing death, malnutrition, and growth delay. Cryptosporidium invades enterocytes where it develops in a unique intracellular niche. Infected cells exhibit profound changes in morphology, physiology and transcriptional activity. How the parasite effects these changes is poorly understood. We explored the localization of highly polymorphic proteins and found members of the C. parvum MEDLE protein family to be translocated into the cytosol of infected cells. All intracellular life stages engage in this export, which occurs after completion of invasion. Mutational studies defined an N-terminal host-targeting motif and demonstrated proteolytic processing at a specific leucine residue. Direct expression of MEDLE2 in mammalian cells triggered an ER stress response, which was also observed during infection. Taken together, our studies reveal the presence of a Cryptosporidium secretion system capable of delivering parasite proteins into the infected enterocyte.

Nucleus

In our application of AuNPs on the leaf surface, we were pushing the Barley Yellow Dwarf Virus (BYDV-PAV) source and Gold nanoparticles (AuNPs) into the plant cell system up on the events of systemic plant defense response. In the infected host cell, the viral coat protein is the first obvious in the cytoplasm. When nanoparticles are applied on leaf surfaces, a large surface area relative to their volume happens. AuNPs solutions are more active and dispersed ooplasm. The correlation between Zeta potential value and Zeta sizer is inverse proportion. Filaments are visible in the nucleopores, the nuclear outline is distorted, and massive clumping of heterochromatin begins as declared. It was mostly found in or around regions of ribosome-associated filaments. Our present study combines TEM and nucleus content in the presence of AuNPS to explore the level of repair mechanism illustrating in TEM micrographs, showing Polyploidy nucleus and segregated chromatin. Multi membranous structure, imaging the AuNPs inside and around the nucleus and Pseudo crystal array is enveloped in an endoplasmic reticulum cisterna (ER).

VIRUSBreakend: Viral Integration Recognition Using Single Breakends

Integration of viruses into infected host cell DNA can causes DNA damage and can disrupt genes. Recent cost reductions and growth of whole genome sequencing has produced a wealth of data in which viral presence and integration detection is possible. While key research and clinically relevant insights can be uncovered, existing software has not achieved widespread adoption, limited in part due to high computational costs, the inability to detect a wide range of viruses, as well as precision and sensitivity. Here, we describe VIRUSBreakend, a high-speed tool that identifies viral DNA presence and genomic integration recognition tool using single breakend variant calling. Single breakends are breakpoints in which only one side has been unambiguously placed. We show that by using a novel virus-centric single breakend variant calling and assembly approach, viral integrations can be identified with high sensitivity and a near-zero false discovery rate, even when integrated in regions of the host genome with low mappability, such as centromeres and telomeres that cannot be reliably called by existing tools. Applying VIRUSBreakend to a large metastatic cancer cohort, we demonstrate that it can reliably detect clinically relevant viral presence and integration including HPV, HBV, MCPyV, EBV, and HHV-8.

Analisis Kestabilan Model Matematika Ko-infeksi Virus Influenza A dan Pneumokokus pada Sel Inang

Co-infection of influenza A virus and pneumococcus is caused by influenza A virus and pneumococcus bacteria which infected host cell at the same time. The purpose of this thesis is to analyze stability of equilibrium point on mathematical model within-host co-infection of influenza A and pneumococcus. Based on anlytical result of the model there are four quilibrium points, non endemic co-infection equilibrium (E0), endemic influenza A virus equilibrium (E1), endemic pneumococcus equilbrium (E2) and endemic co-infection equilibrium (E3). By Next Generation Matrix (NGM), we obtain two basic reproduction number, which are basic reproduction number for influenza A virus (R0v) and basic reproduction number for pneumococcus (R0b). Existence of equilibrium point and local stability of equilibrium point dependent on basic reproduction number. Non endemic co-infection equilibrium is locally asymtotically stable if R0v < 1 and R0b < 1; influenza A virus endemic equilibrium is locally asymtotically stable if R0v > 1 and R0b > 1; pneumococcus endemic equilibrium is locally asymtotically stable if R0v < 1 and R0b > 1. Meanwhile, the co-infection endemic equilibrium is locally asymtotically stable if R0v > 1 and R0b > 1. From the numerical simulation result, it was shown that increasing the number of influenza A virus and pneumococcus made the number of population cell infected by influenza A virus and pneumococcus (co-infection) also increased.

Ultrastructure of intracytoplasmic Rickettsia-like infection of the gills of the teleost Archosargus probatocephalus (Sparidae) in northeastern Brazil

A histopathological survey was conducted to investigate the presence of microparasites in fish Archosargus probatocephalus in a river near Maceió, Brazil. Light microscope observations of fragments of gill showed the presence of small cysts containing numerous myxospores that were morphologically identified as Henneguya. Transmission electron microscopy observations further revealed several gill cells containing groups of prokaryotic cells within large cytoplasmic vacuoles. Each infected host cell displayed a single vacuole containing a variable number of Rickettsia-like cells (up to 11), some of which presented the dumbbell shape characteristic of binary fission. The Rickettsia-like cells were pleomorphic, without a nucleus and with chromatin dispersed in the cytoplasm. They had a thin electron-dense wall of Gram-negative type. The morphology of these prokaryotic was similar to those of the order Rickettsiales and was described as a Rickettsia-like organism. Histopathological evaluation showed that several vacuole membranes had a lysed appearance. Some had ruptured, thus allowing direct contact between the Rickettsia-like organism and the cytoplasm of the host cell. The rupturing of the branchial epithelium may have contributed towards reduction of the surface area of the gills, but it is not possible to say that this was the cause of the host’s death.

First Days in the Life of Naive Human B Lymphocytes Infected with Epstein-Barr Virus

ABSTRACT Epstein-Barr virus (EBV) infects and activates resting human B lymphocytes, reprograms them, induces their proliferation, and establishes a latent infection in them. In established EBV-infected cell lines, many viral latent genes are expressed. Their roles in supporting the continuous proliferation of EBV-infected B cells in vitro are known, but their functions in the early, prelatent phase of infection have not been investigated systematically. In studies during the first 8 days of infection using derivatives of EBV with mutations in single genes of EBVs, we found only Epstein-Barr nuclear antigen 2 (EBNA2) to be essential for activating naive human B lymphocytes, inducing their growth in cell volume, driving them into rapid cell divisions, and preventing cell death in a subset of infected cells. EBNA-LP, latent membrane protein 2A (LMP2A), and the viral microRNAs have supportive, auxiliary functions, but mutants of LMP1, EBNA3A, EBNA3C, and the noncoding Epstein-Barr virus with small RNA (EBERs) had no discernible phenotype compared with wild-type EBV. B cells infected with a double mutant of EBNA3A and 3C had an unexpected proliferative advantage and did not regulate the DNA damage response (DDR) of the infected host cell in the prelatent phase. Even EBNA1, which has very critical long-term functions in maintaining and replicating the viral genomic DNA in established cell lines, was dispensable for the early activation of infected cells. Our findings document that the virus dose is a decisive parameter and indicate that EBNA2 governs the infected cells initially and implements a strictly controlled temporal program independent of other viral latent genes. It thus appears that EBNA2 is sufficient to control all requirements for clonal cellular expansion and to reprogram human B lymphocytes from energetically quiescent to activated cells. IMPORTANCE The preferred target of Epstein-Barr virus (EBV) is human resting B lymphocytes. We found that their infection induces a well-coordinated, time-driven program that starts with a substantial increase in cell volume, followed by cellular DNA synthesis after 3 days and subsequent rapid rounds of cell divisions on the next day accompanied by some DNA replication stress (DRS). Two to 3 days later, the cells decelerate and turn into stably proliferating lymphoblast cell lines. With the aid of 16 different recombinant EBV strains, we investigated the individual contributions of EBV’s multiple latent genes during early B-cell infection and found that many do not exert a detectable phenotype or contribute little to EBV’s prelatent phase. The exception is EBNA2 that is essential in governing all aspects of B-cell reprogramming. EBV relies on EBNA2 to turn the infected B lymphocytes into proliferating lymphoblasts preparing the infected host cell for the ensuing stable, latent phase of viral infection. In the early steps of B-cell reprogramming, viral latent genes other than EBNA2 are dispensable, but some, EBNA-LP, for example, support the viral program and presumably stabilize the infected cells once viral latency is established.

A Novel Series of Sialic Acid-Based Influenza Virus Inhibitors that Target Influenza Virus Neuraminidase

Influenza virus continues to be a clinically-significant human pathogen that causes bothepidemics and pandemics. Successful inhibition of the viral neuraminidase hinders the release ofvirion progeny from the infected host cell and significantly reduces further virus spread [...]

The first days in the life of naïve human B-lymphocytes infected with Epstein-Barr virus

Epstein-Barr virus (EBV) infects and activates resting human B-lymphocytes, reprograms them, induces their proliferation, and establishes a latent infection in them. In established EBV-infected cell lines many viral latent genes are expressed. Their roles in supporting the continuous proliferation of EBV-infected B cellsin vitroare known, but their functions in the early, pre-latent phase of infection have not been investigated systematically. In studies during the first eight days of infection using derivatives of EBV with mutations in single genes of EBVs we found only EBNA2 to be essential for activating naïve human B-lymphocytes, inducing their growth in cell volume, driving them into rapid cell divisions, and preventing cell death in a subset of infected cells. EBNA-LP, LMP2A and the viral microRNAs have supportive, auxiliary functions, but mutants of LMP1, EBNA3A, EBNA3C, and the noncoding EBER RNAs had no discernable phenotype compared with wild-type EBV. B cells infected with a double mutant of EBNA3A and 3C had an unexpected proliferative advantage and did not regulate the DNA damage response (DDR) of the infected host cell in the pre-latent phase. Even EBNA1 which has very critical long-term functions in maintaining and replicating the viral genomic DNA in established cell lines, was dispensable for the early activation of infected cells. Our findings document that the virus dose is a critical parameter and indicate that EBNA2 governs the infected cells initially and implements a strictly controlled temporal program independent of other viral latent genes. It thus appears that EBNA2 is sufficient to control all requirements for clonal cellular expansion and to reprogram human B-lymphocytes from energetically quiescent to activated cells.Author summaryThe preferred target of Epstein-Barr virus (EBV) are human resting B-lymphocytes. We found that their infection induces a well-coordinated, time-driven program that starts with a substantial increase in cell volume followed by cellular DNA synthesis after three days and subsequent rapid rounds of cell divisions on the next day accompanied by some DNA replication stress (DRS). Two to three days later the cells decelerate and turn into stably proliferating lymphoblast cell lines. With the aid of 16 different recombinant EBV strains we investigated the individual contributions of EBV’s multiple latent genes during early B-cell infection and found that many do not exert a detectable phenotype or contribute little to EBV’s pre-latent phase. The exception is EBNA2 that is essential in governing all aspects of B-cell reprogramming. EBV relies on EBNA2 to turn the infected B-lymphocytes into proliferating lymphoblasts preparing the infected host cell for the ensuing stable, latent phase of viral infection. In the early steps of B-cell reprogramming viral latent genes other than EBNA2 are dispensable but some, EBNA-LP for example, support the viral program and presumably stabilize the infected cells once viral latency is established.