Structural basis of host protein hijacking in human T-cell leukemia virus integration

Integration of the reverse-transcribed viral DNA into host chromosomes is a critical step in the life-cycle of retroviruses, including an oncogenic delta(δ)-retrovirus human T-cell leukemia virus type-1 (HTLV-1). Retroviral integrase forms a higher order nucleoprotein assembly (intasome) to catalyze the integration reaction, in which the roles of host factors remain poorly understood. Here, we use cryo-electron microscopy to visualize the HTLV-1 intasome at 3.7-Å resolution. The structure together with functional analyses reveal that the B56γ (B'γ) subunit of an essential host enzyme, protein phosphatase 2 A (PP2A), is repurposed as an integral component of the intasome to mediate HTLV-1 integration. Our studies reveal a key host-virus interaction underlying the replication of an important human pathogen and highlight divergent integration strategies of retroviruses.

In silico screening of natural compounds against COVID-19 by targeting Mpro and ACE2 using molecular docking

OBJECTIVE

Currently, Coronavirus COVID-19 is spreading worldwide very rapidly and its control is very difficult because there is no effective vaccine or drugs available in markets. This virus can infect both animals and people and cause illnesses of the respiratory tract. WHO has declared Coronavirus as pandemic and the whole world is fighting against Coronavirus. Globally, more than 199,478 people have been diagnosed with COVID-19. As of March 18, 2020, more than 167 countries have been affected and more than 8000 deaths have been reported. The main country being affected is China followed by Italy, Iran, Spain, France, and the USA.

MATERIALS AND METHODS

Since there are no effective drugs available against Coronavirus, we conducted virtual screening of phytochemicals to find novel compounds against this virus. Hence, we created a phytochemical library of 318 phytochemicals from 11 plants which have been reported as antiviral, antibacterial and antifungal activity. The phytochemical library was subjected to virtual screening against molecular targets; Main protease (Mpro) and Angiotensin-Converting Enzyme 2 (ACE2).

RESULTS

Top 10 compounds were selected from each target which had better and significantly low binding energy as compared to the reference molecule.

CONCLUSIONS

Based on the binding energy score, we suggest that these compounds can be tested against Coronavirus and used to develop effective antiviral drugs.

Efinaconazole topical solution, 10%: formulation development program of a new topical treatment of toenail onychomycosis

Transungual drug delivery of antifungals is considered highly desirable to treat common nail disorders such as onychomycosis, due to localized effects, and improved adherence resulting from minimal systemic adverse events. However, the development of effective topical therapies has been hampered by poor nail penetration. An effective topical antifungal must permeate through, and under the dense keratinized nail plate to the site of infection in the nail bed and nail matrix. We present here the formulation development program to provide effective transungual and subungual delivery of efinaconazole, the first topical broad spectrum triazole specifically developed for onychomycosis treatment. We discuss the important aspects encompassing the formulation development program for efinaconazole topical solution, 10%, focusing on its solubility in a number of solvents, in vitro penetration through the nail, and in vivo efficacy. Efinaconazole topical solution, 10% is a stable, non-lacquer, antifungal with a unique combination of ingredients added to an alcohol-based formulation to provide low surface tension and good wetting properties. This low surface tension is believed to affect effective transungual delivery of efinaconazole and believed to provide a dual mode of delivery by accessing the nail bed by wicking into the space between the nail and nail plate.

Multiple approaches towards understanding the type II secretion system

Transport of folded proteins across membranes is a feat accomplished by few biomacromolecular machines. One of the machineries able to do so is the sophisticated type II secretion system (T2SS). It can translocate key virulence factors from the bacterial periplasm into the lumen of the gut of the human host. A prime example is the secretion of cholera toxin by Vibrio cholerae. The T2SS consists of ~12 different proteins, most of these present in multiple copies, organized into three subassemblies: (i) the Inner Membrane Platform; (ii) the Pseudopilus in the periplasm, which acts most likely as a piston pushing exoproteins through the outer membrane pore; (iii) the Outer Membrane Complex, allowing passage of ~100 kDa folded proteins. We have determined crystal structures from more than a dozen T2SS domains, yet, a full understanding of the architecture and mechanism of action of the T2SS remains a formidable challenge. Our approaches include the use of "assistant-multimers" to promote recalcitrant multimer formation and of nanobodies to overcome reluctant crystal formation. The Inner Membrane Platform is interacting with the secretion ATPase GspE which most likely needs to be hexameric for full activity. Full-length GspE co-crystallized with its major partner, the cytoplasmic domain of GspL, revealed a tremendous flexibility of this ATPase, and, most unexpectedly, also the organization of the same linear arrangement of cyto-GspL domains throughout three entirely different crystal forms. Two very different hexamers of GspE were elucidated by linking the GspE subunit to the subunit of Hcp1, which successfully acted as an "assistant hexamer", inducing hexamer formation by GspE. The dodecameric nature of the ~ 850 kDa GspD, the major component of the Outer Membrane Complex, evident in earlier electron microscopy studies, was observed in the dodecameric ring-like helix in crystals of its N-terminal domain. The contacts between GspD and the inner-membrane protein GspC will be discussed as well as the remarkably frequent occurrence of dimers of Inner Membrane Platform domains. How dimers are co-assembled with an ATPase hexamer with C6 symmetry and the Outer Membrane Complex dodecamer with C12 symmetry remains one of the many fascinating outstanding questions of the T2SS.

The contemporary management of midface and craniofacial trauma

The successful management of midface and craniofacial trauma requires a thorough understanding of the anatomy and functional demands of this complex region. To achieve optimal outcomes, it is necessary that these injuries are accurately diagnosed and managed in a multi-disciplinary environment at the appropriate time. This review article discusses an overview of these injuries and highlights some of the key principles of management.

In vitro reconstitution of Escherichia coli O86 O antigen repeating unit

Polysaccharides constitute a major component of the bacterial cell surface. They play critical roles in the interactions between bacteria and the host environments, and consequently contribute to the virulence of pathogens. The lipopolysaccharide (LPS) found on the surface of gram-negative bacteria consists of three parts: lipid A, a core oligosaccharide, and the O antigen. The O antigen is the outermost part of LPS and contains multiple oligosaccharide repeating units. Biosynthesis of the O-repeating unit is the first committed step in LPS biosynthesis. We sequenced and characterized the O-antigen biosynthetic gene cluster of Escherichia coli serotype O86. Four glycosyltransferases encoded by the genes within the cluster were cloned and overexpressed. In vitro reconstitution of the O-repeating unit of E. coli 086 was achieved via using these enzymes.

Giardiasis--clinical and diagnostic perspective

Fifty patients of chronic diarrhoea in the pediatric age group admitted in Kalawati Saran Children's Hospital were studied. Thirty cases were diagnosed to be suffering from giardiasis based on microscopy of fecal and/or duodenal fluid specimens. Fecal specimen microscopy missed two cases which were diagnosed by duodenal aspirate microscopy and vice-versa. All fecal specimens were negative on culture, while duodenal aspirate culture gave large number of false negative results. Serum immunoglobulin levels did not show significant changes. Thus, routine microscopic testing is presently the best means for early diagnosis of giardiasis.

Carabelli's trait in Indian students at Manipal, Karnataka

Occurrence of the various forms of Carabelli's trait on maxillary first permanent molars was studied in 376 Indian students at Manipal, Karnataka, a state in south India. The trait was found absent in 64.4% of the teeth studied. Slight tubercles were found more often than pronounced tubercles and more tubercles were found in males than females; conversely the absence of the trait was observed more often in girls than boys. The sample was divided into two groups. Group I consisted of North Indians and Group II consisted of South Indians. Variations in occurrence of the trait between North Indian and South Indian students were studied and it was found to occur almost equally in both groups. The study was extended to observe variations in occurrence of the trait between Indian students of Indian and Foreign nationality but no significant variation was observed.

Aqueous kinetics of sisomicin sulphate

Sisomicin sulphate is a new-generation aminoglycoside with a broad spectrum of antimicrobial activity that includes Pseudomonas aeruginosa. It is superior to gentamicin against indole-negative Proteus and some resistant strains of Pseudomonas. The ocular pharmacokinetics of sisomicin have not been explored. We used the agar diffusion technique of microbial assay to determine the aqueous penetration and bioavailability of a subconjunctivally placed standard dose of 20 mg/0.4 ml of sisomicin sulphate in 20 human volunteers undergoing elective cataract surgery. A peak concentration of 16.4 mg/l was found in the aqueous humour 78 minutes after injection, which is 65 times the minimum inhibitory concentration for Pseudomonas. The antibiotic was bioavailable up to 1203 minutes after injection in a concentration of 0.9 mg/l, which easily covers the minimum inhibitory concentration of Staphylococcus aureus and Pseudomonas. The antibiotic disappears from the aqueous humour at the 1434 minute interval (approximately 24 hours). The elimination half-life (t1/2 of sisomicin was determined to be 5.16 hours (K = 0.134/hour) and the aqueous clearance was 2.87 microliters/min.

Pharmacologic management of patent ductus arteriosus

The incidence, pathophysiology, and clinical findings of symptomatic patent ductus arteriosus (PDA) are reviewed, and the pharmacologic management of symptomatic PDA is discussed. Spontaneous closure of the ductus arteriosus (DA) usually occurs within four days after birth in most premature and full-term infants. The incidence of PDA is related to birth weight in premature infants and has been shown to decrease with an increase in birth weight. Clinical findings are reviewed. Prophylactic treatment in the first few hours after birth may not be needed in most premature infants. Treatment should be considered only if the ductus becomes symptomatic. Medical management consists of respiratory support, fluid restriction, diuretics, digoxin, and indomethacin. Respiratory support, fluid restriction, and diuretics are used as first-line treatment of symptomatic PDA. Digoxin cannot be recommended as part of first-line therapy, since its risks seem to outweigh the benefits in preterm infants. Indomethacin should be used only if other standard measures including fluid restriction and diuretic treatment fail. The mechanism of action, pharmacokinetics, adverse effects, and drug interactions of indomethacin are discussed. Symptomatic PDA can increase morbidity and mortality, especially in very low birth weight infants. Treatment of symptomatic PDA may decrease the morbidity associated with this condition.