KSHV Genome Replication and Maintenance

Kaposi’s sarcoma associated herpesvirus (KSHV) or human herpesvirus 8 (HHV8) is a major etiological agent for multiple severe malignancies in immunocompromised patients. KSHV establishes lifetime persistence in the infected individuals and displays two distinct life cycles, generally a prolonged passive latent, and a short productive or lytic cycle. During latent phase, the viral episome is tethered to the host chromosome and replicates once during every cell division. Latency-associated nuclear antigen (LANA) is a predominant multifunctional nuclear protein expressed during latency, which plays a central role in episome tethering, replication and perpetual segregation of the episomes during cell division. LANA binds cooperatively to LANA binding sites (LBS) within the terminal repeat (TR) region of the viral episome as well as to the cellular nucleosomal proteins to tether viral episome to the host chromosome. LANA has been shown to modulate multiple cellular signaling pathways and recruits various cellular proteins such as chromatin modifying enzymes, replication factors, transcription factors and cellular mitotic framework to maintain a successful latent infection. Although many other regions within the KSHV genome can initiate replication, KSHV TR is important for latent DNA replication and possible segregation of the replicated episomes. Binding of LANA to LBS favors the recruitment of various replication factors to initiate LANA dependent DNA replication. In this review, we discuss the molecular mechanisms relevant to KSHV genome replication, segregation, and maintenance of latency

The Modulation of Apoptotic Pathways by Gammaherpesviruses

Apoptosis or programmed cell death is a tightly regulated process fundamental for cellular development and elimination of damaged or infected cells during the maintenance of cellular homeostasis. It is also an important cellular defense mechanism against viral invasion. In many instances, abnormal regulation of apoptosis has been associated with a number of diseases, including cancer development. Following infection of host cells, persistent and oncogenic viruses such as the members of the Gammaherpesvirus family employ a number of different mechanisms to avoid the host cell’s burglar alarm and to alter the extrinsic and intrinsic apoptotic pathways by either deregulating the expressions of cellular signaling genes or by encoding the viral homologues of cellular genes. In this review, we summarize the recent findings on how gammaherpesviruses inhibit cellular apoptosis via virus-encoded proteins by mediating modification of numerous signal transduction pathways. We also list the key viral anti-apoptotic proteins that could be exploited as effective targets for novel antiviral therapies in order to stimulate apoptosis in different types of cancer cells

Pojava bruceloze na farmi mliječnih krava i mogućnost njenog prijenosa na ljude u Himachal Pradesh, Indija.

Brucellosis is an important disease of livestock species and wild animals, as well as a significant health hazard in contact human beings, causing a variety of reproductive disorders in cattle under intensive farming. This report is about an outbreak of brucellosis in an organized dairy farm, leading to abortions, retained placenta and stillbirths in cows. The Brucella abortus biotype-I was isolated from placentas, uterine discharges, vaginal swabs and foetal stomach contents collected from infected animals. The serological study, employing rose bengal plate test (RBPT) and serum agglutination test (SAT), revealed involvement of both B. abortus and B. melitensis in all affected cows. Seropositive cases for B. melitensis were also found among 10% of contact animal handlers, having a history of human brucellosis-like symptoms. The isolates were found sensitive to streptomycin, chlortetracycline, ciprofloxacin, ampicillin, tetracycline and gentamicin. The haematological study revealed severe monocytosis averaging 33% and lymphocytosis averaging 32.8% in all infected animals.Bruceloza je važna bolest domaćih i divljih životinja, koja predstavlja prijetnju za zdravlje ljudi u dodiru s inficiranim životinjama. Očituje se različitim reprodukcijskim poremećajima. Opisana je pojava bruceloze na farmi mliječnih krava, gdje je uzrokovala pobačaje, zaostajanje posteljice i mrtvorođenja. Brucella abortus biotip I bila je izdvojena iz posteljica, materničnih iscjedaka i vaginalnih obrisaka te sadržaja sirišta pobačenih plodova. Serološkim pretragama pomoću aglutinacijskog i serum aglutinacijskog testa u zaraženih životinja bile su dokazane vrste B. abortus i B. melitensis. Serološki pozitivni nalazi za B. melitensis dokazani su u 10% osoba koje su bile u dodiru sa životinjama, a u anamnezi je bilo ustanovljeno da su imale kliničke znakove slične brucelozi. Izdvojene brucele bile su osjetljive na streptomicin, klortetraciklin, ciprofloksacin, ampicilin, tetraciklin i gentamicin. Hematološkom pretragom dokazana je monocitoza u 33% te limfocitozu u 32,8% svih inficiranih životinja

Development of immunoglobulin diversity at the heavy chain locus of cattle

Immunoglobulins (Ig) are formed by combinatorial recombination of a set of germline genes and undergo mutation in B-lymphocytes as they develop and mature. Combinatorial assortment can result in enormous diversification of the primary Ig repertoire in species where the number and variability within these segments is high (e.g. humans and mice). Many other species are unable to diversify the primary repertoire through rearrangement. In these animals, somatic hypermutation and gene conversion play a major role in driving pre-immune diversity. The bovine humoral immune system is not capable of generating a significant level of heavy chain Ig diversity through combinatorial assortment due to the small size of the IgH gene family and the low diversity apparent within the CDRs of the VH segments of this family. To learn more of the molecular processes responsible for diversification, this study hypothesized that somatic hypermutation would introduce nucleotide substitutions throughout the Ig reading frame including the JH-C intron whereas if gene conversion were the dominant process behind diversification, modifications would be confined to the Ig reading frame. To distinguish these possibilities, Ig heavy chain sequences were recovered from the rearranged locus using lymphoid tissues of cattle of different ages for sequence analysis. This also allowed determination of the timing of Ig diversification and comparison of the extent of diversification. Analysis revealed that single base substitutions predominated, with purines targeted more frequently than pyrimidines and transitions favoured over transversions. Seventeen deletions spanning 1 to 26 nucleotides and 5 insertions in the range of 1 to 3 bases were also observed. As would be expected, mutational hotspots were encountered in CDR1 (complementary determining region) and CDR2 and the sequences downstream of FR4. The modified region extended into unutilized parts of the JH locus and downstream intron and with mutations occurring as frequently as in CDR2. The frequency of mutation decreased over the 579 bases lying 3' to the rearranged VDJ gene. Therefore, the data were consistent with the predicted pattern of somatic hypermutation. (Abstract shortened by ProQuest.)

Regulation of Chitin Oligosaccharides Utilization in Escherichia Coli

The genome of Escherichia coli harbors several catabolic operons involved in the utilization of a wide variety of natural compounds as carbon sources. The chitobiose (chu) operons of E.coli Is involved in the utilization of chitobiose(disaccharide of N-acety1-D-glucosamine) and cellbiose (disaccharide of glucose) derived from the two most abundant naturally occurring carbon sources on earth, chitin and cellulose respectively. The operon consists of the chbBCARFG genes coding for transport, regulation and hydrolysis functions required to utilize these compounds; the chuyBCA genes code for a multi-subuni PTS transporter ; the chuR codes for a dual function repressor/activator of the operon; the chbF codes for a phospho-glucosidase and the chbG codes for a protein of unknown function. The chu operon Is regulated by three transcription factors; NagC, a key regulator of the nag genes involved in amino sugar metabolism; ChbR, a dual function operon-specific regulator; and CRP_cAMP. The operon is repressed by NagC and ChbR in the absence of catabolic substrate. In the presence of chitobiose, expression is induced by the abrogation of NagC-mediated repression by GlcNAc-6-P generated by the hydrolysis of chitobiose-6-P and subsequent activation of transcription by ChbR and CPR-cAMP. Wild type E.coli connot utilize cellbiose due to the inability of cellbiose to induce expression from the operon. The simultaneous presence of a loss of function mutation in nagC and a gain –of-function mutation in chbR is necessary and sufficient to allow cellbiose to induce expression and confer on E.coli the ability to utilize cellbiose. The activation step by ChbR and CPR-cAMP requires an inducer that is recognized by ChbR. The chemical identity of the inducer and the mechanism of transcriptional activation by ChbR and CPR-cAMP are not understood. The studies described in the chapter 2 shows that chbG is essential for the utilization of the acetylated sugars chitobiose and chitotriose while it is dispensable for the sugars lacking the acety1group such as cellobiose and chitosan dimer, a disaccharide of N-glucosamine. ChbG is produced as a cytosolic protein and removes one acety1 group from chitobiose and chitotriose thus shows a mono-decetylase activity. Taken together, the observing suggest that ChbG deacetylates chitobiose-6-P and chitotriose-6-P producing the mono-decetylated from of the sugars. The deacetylateion is necessary for their recognition both as inducers by ChbR to activate transcription along with CRP-cAMP and as substractes by phosop-glucosidase ChbF. Cellobiose positive(Cel+) mutants carrying nagC delection and different gain-of-function mutations in chbR are independent of chbG for induction by chitobiose suggesting that the mutations in ChbR can allow it to recognize the acetylated form of chitobiose-6-P. Despite normal induction, the mutants to grow on chitobiose without chbG are consistant with the requirement of deacetylation for hydrolysis by ChbF. The prediction active site of chbG was validated by demonstrating the loss of chbG function upon alanine substitution of the putative metal binding residues. Vibro cholerace ChbG can complement the function of E.coli ChbG indicating that ChbG is conserved in both the organisms. The studies presented in chapter 3 address the mechanism of transcriptional activation of the chb operon by ChbR and CPR-cAMP. ChbR and CPR-cAMP function in a synergistic manner in response to the induction signal. The synergy is not because of their cooperative binding to the DNA. The role of CRP as a class I activator via the known mechanism involving interaction between the Activation region1 (AR1) and the C-terminal domain of the alpha subunit of RNA polymerase (CTD) was not crucial for the chb operon. A direct interaction between the two activators in virto was observed. Based on these results and the close spacing of the synergy is due to interaction between the two regulators bound to DNA that is enhanced in the presence of the inducer, binding about an optimal confirmation in ChbR required to interact with RNA polymerase. ChbR contacts different residues in the subunit in response to cellbiose and chitobiose; whereas it utilizes the known residues in the presence cellbiose, it appears to require different and unknown residues for induction in the presence of chitobiose. In conclusion, the studies reported in chapter 2 and 3 provide an understanding of the regulation of the chitin oligosaccharides utilization in E.coli at different levels. The broad implications of these studies and possible future directions are discussed in chapter 4. ChbG is an evolutionary conserved protein found in both prokaryotes and enkayotes including humans. ChbG homologs have been implicated in inflammatory bowel disorders in humans and development in metazoans. Therefore, the studies on chbG described in this thesis have been broader significance

A Simple Approach for Black Out Problem

Antennas surrounding by the plasma medium does not radiate for all the frequencies but only for those which are greater than the plasma frequency. Here we have proposed a cylindrical (axial magnetized) antenna system which radiates for all frequencies irrespective of plasma frequency and this is the solution for the black-out situation which occurs for certain frequencies

Adult Necrotising Enterocolitis: a Rare Entity

A case of Adult Necrotising Enterocolitis in an adult female whom diagnosed with intestinal obstruction was reported. On exploratory laparotomy, the mechanical caused was not found although major part of small bowel, caecum and proximal ascending colon were gangrenous along with intervening normal parts. Resection of affected bowel was performed followed by jejunostomy and transverse colostomy. Unfortunately, the patient not survive in the postoperative periods. Adult Necrotising Enterocolitis may mimic intestinal obstruction clinically or radiologically and prompt medical and surgical intervention is indicated in doubtful cases although it carries a poor prognosis. Key words: adult necrotizing Enterocolitis, non-occlusive mesenteric ischemia, gangrenous bowe

Klinički mastitis uzrokovan gljivicom Geotrichum candidum.

Mastitis, which has multiple and complex aetiology, is a common syndrome among bovines and inflicts enormous losses on livestock owners. The mastitis cases are infectious in nature and are usually caused by bacteria, fungi/yeasts and some algae. An interesting case of protracted clinical mastitis in a Holstein-Fresian cow in its third lactation was encountered, with exclusive involvement of Geotrichum candidum, an extremely rare in occurrence. G. candidum, an opportunisitic, keratinophilic yeast-like fungus, was identified by its diagnostic colonial characteristics and microscopic morphology, i.e. rectangular arthrospores (arthroconidia) after staining with lactophenol cotton blue stain (LPCB) in a wet mount, and Gram’s stain after heat fixation of the smear. This fungal isolate was also subjected to in-vitro antifungal sensitivity test against cotrimazole, ketoconazole, miconazole, amphotericin-B and nystatin, but was found sensitive only to amphotericin-B.Mastitis u goveda je kompleksne etiologije i nanosi velike gospodarske štete. Najčešće je uzrokovan bakterijama, gljivicama i rijetko nekim algama. U radu je prikazana zanimljiva i veoma rijetka upala vimena krave holštajn-frizijske pasmine uzrokovana gljivicom Geotrichum candidum. Gljivica G. candidum je keratinofilna gljivica slična kvascima. Identificirana je na osnovi karakterističnih kolonija i morfoloških značajki artrospora vidljivih nakon bojenja. Određena je i osjetljivost izdvojene gljivice prema klotrimazolu, ketokonazolu, mikonazolu, amfotericinu B i nistatinu. Osjetljivost je utvrđena samo za amfotericin B

Role of Viruses in the Pathogenesis of Multiple Sclerosis

Multiple sclerosis (MS) is an immune inflammatory disease, where the underlying etiological cause remains elusive. Multiple triggering factors have been suggested, including environmental, genetic and gender components. However, underlying infectious triggers to the disease are also suspected. There is an increasing abundance of evidence supporting a viral etiology to MS, including the efficacy of interferon therapy and over-detection of viral antibodies and nucleic acids when compared with healthy patients. Several viruses have been proposed as potential triggering agents, including Epstein-Barr virus, human herpesvirus 6, varicella-zoster virus, cytomegalovirus, John Cunningham virus and human endogenous retroviruses. These viruses are all near ubiquitous and have a high prevalence in adult populations (or in the case of the retroviruses are actually part of the genome). They can establish lifelong infections with periods of reactivation, which may be linked to the relapsing nature of MS. In this review, the evidence for a role for viral infection in MS will be discussed with an emphasis on immune system activation related to MS disease pathogenesis