Immune and Oxidative Response against Sonicated Antigen of Mycoplasma capricolum subspecies capripneumonia-A Causative Agent of Contagious Caprine Pleuropneumonia

Vaccines are vital for prevention and control of mycoplasma diseases. The exploration of a vaccine candidate for the development of a vaccine is imperative. The present study envisages the evaluation of immune and oxidative response against an adjuvanted, sonicated antigen of Mycoplasma capricolum subsp. capripneumonia in male Angora rabbits (1 year old, 2 kg) divided in four groups, each having six animals. Group 1 was the healthy control and received 1 mL PBS via subcutaneous route. Group 2 was administered 1 mL of saponin-adjuvanted and -sonicated antigen, Group 3 was given 1 mL of montanide ISA 50-adjuvanted and-sonicated antigen, and Group 4 was given 1 mL of standard vaccine via subcutaneous route. Animals were evaluated for cellular and humoral immune response and oxidative parameters at 0, 7, 14, 21, and 28 days of the study. Total leukocytic, neutrophilic, and basophilic counts showed a significant (p < 0.05) increase in vaccinated groups compared to the healthy group on most of the intervals. TNF-α levels were significantly (p < 0.05) higher in the Group 2 than the Group 1 at all the time intervals and more comparable to Group 4 than Group 3. IL-10 levels were significantly (p < 0.05) higher in vaccinated groups compared to the healthy group on days 14, 21, and 28, but were lower in Group 3 than in Group 2 and Group 4. More hypersensitivity as inflammation and histopathological cellular infiltration in the ear was produced in Group 2 and Group 4 than in Group 3. IgG levels were significantly (p < 0.05) higher in Group 2 and Group 4 than in Group 3 on days 14 and 21. Antibody titers were comparatively higher in Group 4, followed by Group 2 and 3, than Group 1. Significantly (p < 0.05) higher oxidant and lower antioxidant values were noted in Group 2 and 4 compared to Group 3 and Group 1 on most of the intervals. The TLC and antibody titer showed increasing trend throughout the trial, whereas TNF-α, IgG, L, M and E started decreasing from day 14, and IL-10, N and B started decreasing from day 21. This study concludes that the saponin-adjuvanted and-sonicated antigen induces comparatively higher immune response than montanide but is associated with oxidative and inflammatory reactions.

Immunotherapies and immunomodulatory approaches in clinical trials - a mini review

The coronavirus disease (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created havoc worldwide. Due to the non-availability of any vaccine or drugs against COVID-19, immunotherapies involving convalescent plasma, immunoglobulins, antibodies (monoclonal or polyclonal), and the use of immunomodulatory agents to enhance immunity are valuable alternative options. Cell-based therapies including natural killer cells, T cells, stem cells along with cytokines and toll-like receptors (TLRs) based therapies are also being exploited potentially against COVID-19. Future research need to strengthen the field of developing effective immunotherapeutics and immunomodulators with a thrust of providing appropriate, affordable, convenient, and cost-effective prophylactic and treatment regimens to combat global COVID-19 crisis that has led to a state of medical emergency enforcing entire countries of the world to devote their research infrastructure and manpower in tackling this pandemic.

Novel Candidates for Vaccine Development Against Mycoplasma Capricolum Subspecies Capripneumoniae (Mccp)-Current Knowledge and Future Prospects

Exploration of novel candidates for vaccine development against Mycoplasma capricolum subspecies capripneumoniae (Mccp), the causative agent of contagious caprine pleuropneumonia (CCPP), has recently gained immense importance due to both the increased number of outbreaks and the alarming risk of transboundary spread of disease. Treatment by antibiotics as the only therapeutic strategy is not a viable option due to pathogen persistence, economic issues, and concerns of antibiotic resistance. Therefore, prophylactics or vaccines are becoming important under the current scenario. For quite some time inactivated, killed, or attenuated vaccines proved to be beneficial and provided good immunity up to a year. However, their adverse effects and requirement for larger doses led to the need for production of large quantities of Mccp. This is challenging because the required culture medium is costly and Mycoplasma growth is fastidious and slow. Furthermore, quality control is always an issue with such vaccines. Currently, novel candidate antigens including capsular polysaccharides (CPS), proteins, enzymes, and genes are being evaluated for potential use as vaccines. These have shown potential immunogenicity with promising results in eliciting protective immune responses. Being easy to produce, specific, effective and free from side effects, these novel vaccine candidates can revolutionize vaccination against CCPP. Use of novel proteomic approaches, including sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis, immunoblotting, matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry, tandem mass spectroscopy, fast protein liquid chromatography (FPLC), bioinformatics, computerized simulation and genomic approaches, including multilocus sequence analysis, next-generation sequencing, basic local alignment search tool (BLAST), gene expression, and recombinant expression, will further enable recognition of ideal antigenic proteins and virulence genes with vaccination potential.

Comparative evaluation of different therapeutic protocols for contagious caprine pleuropneumonia in Himalayan Pashmina goats

Therapeutic management of contagious caprine pleuroneumonia (CCPP) involves mostly the use of oxytetracycline followed by enrofloxacin and rarely tylosin. In many parts of the world including India, the former antibiotics are commonly available than the latter. Therefore, prolonged use of the same leads to the development of antibiotic resistance and decreased efficacy of drug. Besides, inflammatory and allergic pathogenesis of CCPP envisages combination therapy. In this study, we evaluated the effectiveness of the combination therapy using different antibiotics (oxytetracycyline @ 10: group I, enrofloxacin @ 5 group II, and tylosin: group III, @ 10 mg/kg body weight), along with anti-inflammatory (meloxicam @ 0.5 mg/kg) and anti-allergic (pheneramine maleate @ 1.0 mg/kg) drugs. These drugs were given intramuscularly at the interval of 48 h for four times in three test groups (n = 10) of Pashmina goats, viz. groups I, II, and III, respectively, affected with CCPP. Group IV (n = 10) was kept as healthy control when group V (n = 10) treated with oxytetracycline @ 10 mg/kg alone was used as positive control. Clinical signs, clinical parameters, pro-inflammatory cytokine (tumor necrosis factor alpha (TNF-α)), and oxidative stress indices (total oxidant status (TOS), total antioxidant status (TAS)) were evaluated at hours 0, 48, 96, and 144 of experimental trial. Tylosin-based combination therapy resulted in a rapid and favorable recovery resulting in restoration of normal body temperature (102.46 ± 0.31 °F), respiration rate (16.30 ± 0.79 per minute), and heart rate (89.50 ± 2.63 per minute) compared to the oxytetracycline (102.95 ± 0.13, 21.30 ± 1.12, 86.00 ± 2.33, respectively) and enrofloxacin (102.97 ± 0.19, 21.00 ± 1.25, 90.00 ± 2.58, respectively) treated groups. By hour 144, all the groups showed restoration of clinical parameters of normal health and diminishing signs of CCPP, viz. fever, dyspnea, coughing, nasal discharge, weakness, and pleurodynia. Significant (P ≤ 0.05) decrease in levels of TNF-α and non-significant (P > 0.05) decrease in levels of TOS and an increase in levels of TAS were noted from hour 0 to 144 in all the test groups. Within the groups, no significant (P > 0.05) change was noted in TNF-α, TOS, and TAS levels; however, TNF-α levels were comparatively lower in group III. Hematological parameters did not differ significantly (P > 0.05). From these findings, it can be inferred that tylosin-based combination therapy is relatively better for early, rapid, and safe recovery besides minimizing inflammatory and oxidative cascade in CCPP affected Pashmina goats compared to oxytetracycline- and enrofloxacin-based therapies.

Contagious caprine pleuropneumonia - a comprehensive review

Contagious caprine pleuropneumonia (CCPP) is a serious disease of goats, occasionally sheep and wild ruminants, caused by Mycoplasma capricolum subspecies capripneumoniae (Mccp). The disease is characterized by severe serofibrinous pleuropneumonia, very high morbidity (∼100%), and mortality (80–100%). CCPP affects goats in more than 40 countries of the world thereby posing a serious threat to goat farming around the globe. The characteristic clinical signs of CCPP are severe respiratory distress associated with sero-mucoid nasal discharge, coughing, dyspnea, pyrexia, pleurodynia, and general malaise. In later stages, severe lobar fibrinous pleuropneumonia, profuse fluid accumulation in pleural cavity, severe congestion of lungs and adhesion formation is observed. Mycoplasmal antigen interactions with host immune system and its role in CCPP pathogenesis are not clearly understood. CCPP is not a zoonotic disease. Diagnosis has overcome cumbersome and lengthy conventional tests involving culture, isolation, and identification by advanced serological (LAT, cELISA) or gene-based amplification of DNA (PCR, RFLP, and hybridization) and sequencing. The latex agglutination test (LAT) is rapid, simple, and better test for field and real-time diagnosis applicable to whole blood or serum and is more sensitive than the CFT and easier than the cELISA. Moreover, the studies on antibiotic sensitivity and exploration of novel antibiotics (fluoroquinolones, macrolides) can help in better therapeutic management besides preventing menace of antibiotic resistance. Re-visiting conventional prophylactic measures focussing on developing novel strain-based or recombinant vaccines using specific antigens (capsular or cellular) should be the most important strategy for controlling the disease worldwide.

Anti-inflammatory effect of dikaempferol rhamnopyranoside, a diflavonoid from Eugenia jambolana Lam. Leaves

Traditionally, the Indian Blackberry or locally called Jamun, Eugenia jambolana Lam. (Syn.: Syzygium cumini), is well known for its pharmacological potential, particularly anti-inflammatory. Here, we studied kaempferol-7-O-α-L-rhamnopyranoside]-4'-O-4'- [kaempferol-7-O-α-L-rhamnopyranoside (EJ-01) isolated from the E. jambolana leaves for possible anti-inflammatory activity. EJ-01 (3, 10 and 30 mg/kg, p.o.) was assessed for anti-inflammatory activity using carrageenan-induced paw edema model in mice by determining edema volume, myeloperoxidase (MPO), nitrite plus nitrate (NOx) and cytokine levels in paw edema tissue. EJ-01 significantly attenuated the edema, MPO levels, tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) levels in the edema of paw at the 5th hour after carrageenan injection at all doses. EJ-01 (30 mg/kg) decreased the nitric oxide (NO) levels of the edema of paw at the 5th hour after carrageenan injection. The anti-inflammatory mechanisms of EJ-01 might be related to the decrease in the level of edema paw by reduced activities of NO and MPO. It probably exerts anti-inflammatory effects through the suppression of TNF-α and IL-1β. Therefore, we conclude that EJ-01 could be positively exploited for itspotential benefits against inflammatory diseases and support the pharmacological basis of E. jambolana as traditional herbal medicine for the treatment of inflammatory diseases.

Results of treatment of distal extra: articular femur fractures with locking plates using minimally invasive approach--experience with 25 consecutive geriatric patients

PURPOSE

Fractures involving the femur in older adults are reasonably common. The aim of this study was to evaluate the results of MIPO technique using locking plates in geriatric patients for distal extra-articular femur fractures.

METHODS

About 25 consecutive patients with distal extra-articular femur fractures aged 60 years and above were treated using locking plates and minimally invasive technique. Patients were studied prospectively over a period of 3 years. Parameters studied included patient demographics, fracture type, time taken for the surgery, time to union and any complications.

RESULTS

Mean age of patients was 66.5 years. Nineteen (76%) patients were females. Most of fractures in our study were type 33A2 fractures (64%). Average time to full weight bearing was 14.32 weeks, and fractures united at an average of 16.88 weeks. There were two (8%) patients with superficial infection, two (8%) with implant tenderness. One (4%) patient developed knee stiffness. Five (20%) patients had extension lag of average 5°. One (4%) patient sustained a peri-implant fracture at 2 months. None of the patients developed non-union or delayed union. According to criteria laid by Schatzker's and Lambert, excellent results were achieved in 22 (88%) patients.

CONCLUSIONS

Outcome of minimally invasive fixation of distal extra-articular femur fractures with locking plates in patients of age 60 years and above seems to be good with high union rate despite high prevalence of osteoporosis and comminution.

Grave's disease associated with immunoglobulin A nephropathy: A rare association

Immunoglobulin A (Ig A) nephropathy is the most common form of primary glomerulonephritis. The association of Ig A nephropathy with Grave's disease has not been reported so far. We report a case of 20-year-old female with Grave's disease who presented with edema, facial puffiness, and decreased urine output. She was found to be hypertensive with renal failure and nephrotic range proteinuria. Renal biopsy revealed features of Ig A nephropathy. The patient was treated with oral corticosteroids (1 mg/kg/day). To our knowledge, this is the first case showing association of Grave's disease with Ig A nephropathy.

Emphysematous pyelonephritis: Outcome with conservative management

Emphysematous pyelonephritis is a life-threatening condition characterized by necrotising gas forming infection of the renal parenchyma. We describe eight patients seen over a period of 2 years, 62.5% males and 37.5% females with age range between 21 and 65 years. About 75% patients had diabetes mellitus. Six patients were managed conservatively. One patient required nephrectomy with percutaneous drainage and one patient died without surgical intervention.

A re-look at the duration of human pregnancy

INTRODUCTION

The duration of human pregnancy is arbitrarily taken as 280 days (40 weeks). Foetuses are considered to be at high risk once pregnancy goes beyond the expected date of confinement. This study was carried out with the aim of determining the mean gestation age of low-risk pregnancies that went into spontaneous labour and the incidence of adverse outcomes in relation to gestation.

METHODS

Low-risk singleton pregnancies admitted in spontaneous labour at a single community hospital in the Udupi district of Karnataka in South India, from December 2002 to December 2003, were analysed for mean gestational age at the onset of spontaneous labour and rates of perinatal complications by gestational age.

RESULTS

Among the 1,094 women who went into spontaneous labour, the mean gestational age was 272.1 +/- 9 days. A significantly increased incidence of meconium-stained amniotic fluid beyond 39 weeks of gestation was observed. 783 of 1,094 women (80 percent) had delivered during the period of 261-280 days of pregnancy (period of one standard deviation around the mean gestational age at delivery). There was significant increase in perinatal morbidity indicators and mortality rates once the pregnancy carried beyond 280 days.

CONCLUSION

Mean gestational age at the onset of labour for women native to the area of study was 272 days (standard deviation 9 days). Pregnancies beyond a duration of 280 days showed significantly increased perinatal morbidity. It is suggested that there is a need for determining the length of gestation and to compile gestation-wise incidence of meconium-stained amniotic fluid as an indicator of foetal maturity or the undisclosed risk factor, in addition to other neonatal morbidity indicators for different populations.

Selective and opposing actions of progesterone receptor isoforms in human endometrial stromal cells

Transcriptional regulation by progesterone is mediated primarily through the two progesterone receptor (PR) isoforms, PR-A and PR-B. Primary human endometrial stromal cell cultures, in which endogenous PR expression was lost, were infected with adenovirus expressing PR-A, PR-B, or both. Global gene expression analysis was conducted on vehicle and 30 nM progesterone (P4) treated cells following 12 h treatment. Interestingly, many genes regulated by PR-B alone or upon PR-A and PR-B co-expression, did not overlap with each other or with the PR-A expression group. Although many genes known to be progestin regulated in the uterus in vivo were also regulated in this study, markedly little overlap with published P4 regulated genes from human breast cancer cells was observed. Progesterone dose response curves were generated for several genes demonstrating gene selective potency and efficacy for each PR isoform. Furthermore, the PR isoforms opposed each other in regulation of tissue factor, with PR-B increasing and PR-A decreasing both mRNA and protein levels. Our data provide a view of global gene expression by PR isoforms in human endometrial cells and a comparison with other cell types. The specific genes and regulation patterns found provide groundwork to revealing the mechanism of PR isoform selectivity, and perhaps ultimately to the tissue selective properties these receptors appear to exhibit.

Enhanced immunogenicity of hepatitis B surface antigen by insertion of a helper T cell epitope from tetanus toxoid

The currently marketed hepatitis B vaccines in the U.S. are based on the recombinant major hepatitis B surface antigen (HBsAg) of hepatitis B virus. Although a large majority of individuals develop protective immunity to HBV-induced disease after three immunizations, routinely a small but a significant percentage of the human population does not respond well to these vaccines. In this report, we describe the generation of a novel HBsAg molecule containing a Th epitope derived from tetanus toxoid (TT). Using recombinant DNA technology. the TT Th epitope (TTe) was inserted into the HBsAg coding sequence. Using a recombinant adenovirus expression system, HBsAg TTe chimeric protein was produced in A549 cells and found to be secreted into culture medium as 22 nm particles. The chimeric HBsAg particles were readily purified by immunoaffinity chromatography and their immunogenicity was evaluated relative to native HBsAg produced in an adenovirus expression system. When evaluated in inbred and outbred strains of mice, HBsAg TTe was shown to enhance several-fold the anti-HBs response relative to native HBsAg. Further enhanced responses were observed in mice primed with TT. This highly immunogenic form of HBsAg has promise as an improved HBsAg subunit vaccine.

The hepatitis C virus NS2 protein generated by NS2-3 autocleavage is required for NS5A phosphorylation

Hepatitis C virus (HCV) is dependent on NS2-3 autocleavage and NS5A phosphorylation for its life cycle. We demonstrate that NS5A, when released from the NS2-5 polyprotein of the BK virus strain, is phosphorylated as two distinct forms, pp56 and pp58. Deletion analysis indicates that the appearance of pp58 requires NS2 in cis, while pp56 is NS2 independent. Disruption of NS2-3 autoproteolysis by directed mutagenesis results in loss of pp58. Expression of a construct producing NS2-3 is sufficient to restore pp58 in trans. These data indicate that generation of functional NS2 via autocleavage of the NS2-3 precursor and NS5A phosphorylation are consecutive processes, suggesting coordinate regulation during virus propagation in vivo.

A novel human estrogen receptor beta: identification and functional analysis of additional N-terminal amino acids

A novel human estrogen receptor beta (hERbeta) was cloned from human testis mRNA, ovary and thymus cDNA utilizing PCR and 5' RACE methods. The 5' end of hERbeta contained an additional open reading frame, in-frame and upstream of the published clones. hERbeta encodes a protein of 530 amino acids with an approximate molecular weight of 63 kDa and is larger than the previously reported rat, mouse and human protein. To determine the functional role of additional N-terminal amino acids, we compared the transcription functions of receptor lacking (hERbetaT) and receptor containing (hERbetaL) this N-terminal extension. hERbetaL is more active than hERbetaT in transactivating ERE-based reporter genes. hERbetaL, but not hERbetaT, attenuated cytokine mediated NFkappaB activation. Taken together, the additional N-terminal amino acids appear to play a role in modulating estrogen responsive gene expression in vitro.

Estrogen regulation of the apolipoprotein AI gene promoter through transcription cofactor sharing

Estrogen replacement therapy increases plasma concentrations of high density lipoprotein and its major protein constituent, apolipoprotein AI (apoAI). Studies with animal model systems, however, suggest opposite effects. In HepG2 cells stably expressing estrogen receptor alpha (ERalpha), 17beta-estradiol (E2) potently inhibited apoAI mRNA steady state levels. ApoAI promoter deletion mapping experiments indicated that ERalpha plus E2 inhibited apoAI activity through the liver-specific enhancer. Although the ERalpha DNA binding domain was essential but not sufficient for apoAI enhancer inhibition, ERalpha binding to the apoAI enhancer could not be detected by electrophoretic mobility shift assays. Western blotting and cotransfection assays showed that ERalpha plus E2 did not influence the abundance or the activity of the hepatocyte-enriched factors HNF-3beta and HNF-4, two transcription factors essential for apoAI enhancer function. Expression of the ERalpha coactivator RIP140 dramatically repressed apoAI enhancer function in cotransfection experiments, suggesting that RIP140 may also function as a coactivator on the apoAI enhancer. Moreover, estrogen regulation of apoAI enhancer activity was dependent upon the balance between ERalpha and RIP140 levels. At low ratios of RIP140 to ERalpha, E2 repressed apoAI enhancer activity, whereas at high ratios this repression was reversed. Regulation of the apoAI gene by estrogen may thus vary in direction and magnitude depending not only on the presence of ERalpha and E2 but also upon the intracellular balance of ERalpha and coactivators utilized by ERalpha and the apoAI enhancer.

Functional properties of a conditionally phenotypic, estrogen-responsive, human osteoblast cell line

Osteoblasts are established targets of estrogen action in bone. We screened 66 conditionally immortalized clonal human osteoblast cell lines for estrogen receptors (ERs) using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for ER alpha mRNA and transactivation of adenovirus-estrogen response element (ERE)-tk-luciferase by 17 beta-estradiol (17 beta-E2) for functional ER protein. One of these cell lines, termed HOB-03-CE6, was chosen for further characterization. The cells, which were conditionally immortalized with a temperature-sensitive SV40 large T antigen, proliferated at the permissive temperature (34 degrees C) but stopped dividing at the nonpermissive temperature (> or = 39 degrees C). Alkaline phosphatase activity and osteocalcin secretion were upregulated by 1 alpha, 25-dihydroxyvitamin D3 in a dose-dependent manner. The cells also expressed type I collagen and other bone matrix proteins, secreted a variety of growth factors and cytokines, formed mineralized nodules based on alizarin red-S and von Kossa histochemical staining, and responded to dexamethasone, all-trans retinoic acid, and transforming growth factor-beta 1. This cell line expressed 42-fold less ER message than MCF-7 human breast cancer cells, as determined by quantitative RT-PCR. However, adenovirus-ERE-tk-luciferase activity was upregulated three- to fivefold in these cells by 17 beta-E2 with an EC50 of 64 pM. Furthermore, this upregulation was suppressed by co-treatment with the anti-estrogen ICI-182, 780. Cytosolic extracts of these cells specifically bound [125I]-17 beta-E2 in a concentration-dependent manner with a Bmax of 2.7 fmoles/mg protein (approximately 1,200 ERs/cell) and a Kd of 0.2 nM. DNA gel-shift analysis using a [32P]-ERE demonstrated the presence of ERs in nuclear extracts of these cells. Moreover, binding of the extracts to this ERE was blocked by a monoclonal antibody to the human ER DNA-binding domain. We evaluated these cells for 14 of 20 reported endogenous responses to 17 beta-E2 in osteoblasts. Although most of these responses appeared to be unaffected by the steroid, 17 beta-E2 suppressed parathyroid hormone-induced cAMP production, as well as basal interleukin-6 mRNA expression; conversely, the steroid upregulated the steady-state expression of alkaline phosphatase message in these cells. In summary, we have identified a clonal, conditionally phenotypic, human osteoblast cell line that expresses functional ERs and exhibits endogenous responses to 17 beta-E2. This cell line will be a valuable in vitro model for exploring some of the molecular mechanisms of estrogen action in bone.

Replication and immunogenicity of Ad7-, Ad4-, and Ad5-hepatitis B virus surface antigen recombinants, with or without a portion of E3 region, in chimpanzees

Human adenovirus vectors containing intact or largely deleted E3 region were used to construct adenovirus-hepatitis B recombinant viruses (Ad-HepB) and shown to produce substantial amount of recombinant protein, hepatitis B surface antigen (HBsAg), in tissue culture. Previously we showed that these viruses were able to elicit good anti-HBs antibodies in a dog model. In the present study, the Ad-HepB viruses were evaluated for replication and immunogenicity in chimpanzees which sustain permissive infection by human adenoviruses. Recombinants containing entire E3 region showed better replication pattern than their E3 deleted counterparts as evidenced by longer duration and high titers of virus shedding. The effect of E3 region was also seen in the antibody titers against HBsAg in that the E3 containing viruses showed better response than the E3 deleted viruses. The importance of E3 region for the development of adenovirus vectored vaccines is further discussed.

Regulated processing of hepatitis C virus core protein is linked to subcellular localization

Posttranslational processing and subcellular localization of the HCV core protein are critical steps involved in the assembly of hepatitis C virus (HCV). In this study, both of these events were investigated by in vitro translation and transient COS-1 cell transfection of core protein expression constructs. Mutations at amino acid residues 173 to 174 and 191 to 192 disrupted processing events at the two putative cleavage sites in the C-terminal hydrophobic region of the core protein, indicating that these residues are implicated in the pathway of core protein maturation. As a result, two forms of core protein, C173 and C191, were detected by immunoblotting. Indirect immunofluorescence experiments showed that core proteins C173 and C191, when produced from HCV full-length protein or various polyprotein precursors, displayed a cytoplasmic localization. The C173 species, however, was translocated to the nucleus when expressed in the absence of C191. These findings indicate that preferential cleavage may occur during core protein maturation and that the association of the C191 with the C173 species may contribute to the distinct subcellular distribution of core protein. This may provide a possible mechanism for the control of the diverse biological functions of core protein during HCV replication and assembly.

Substrate specificity of the NS3 serine proteinase of hepatitis C virus as determined by mutagenesis at the NS3/NS4A junction

Hepatitis C virus (HCV) encodes a polyprotein that is processed to produce the structural and nonstructural proteins of the virus. Nonstructural protein 3 (NS3) is a serine proteinase that cleaves the polyprotein to release the NS4A, NS4B, NS5A, and NS5B proteins. To characterize the substrate specificity of NS3, we synthesized by in vitro translation the polyprotein NS2*-NS3-NS4*P that includes 70% of the NS2 protein, the complete NS3 protein, and 25% of the NS4 protein region attached to substance P, an epitope tag. We demonstrated that NS3 cleaves at the NS3/NS4A junction to release the NS4*P protein. Subsequently, we used this reaction to evaluate the importance of conserved amino acids that flank the NS3/NS4A junction. We replaced amino acids in the P6, P1, and P1' positions of the scissile bond of this junction using site-directed mutagenesis. When the P6 aspartic acid was changed to asparagine, lysine, or serine, NS3-mediated cleavage occurred. When threonine in the P1 position was replaced with other polar amino acids or with amino acids having aliphatic side chains, cleavage occurred, although it was not detected when arginine or tyrosine was present. Replacement of serine in the P1' position with other polar amino acids, with amino acids having aliphatic side chains, or with arginine resulted in NS3-mediated cleavage. Thus, since fewer amino acids in the P1 position supported cleavage than in the P6 or P1' positions, the P1 position of the scissile bond may play a more important role in defining the substrate specificity of the HCV NS3 proteinase.

Efficacy of adenovirus-vectored respiratory syncytial virus vaccines in a new ferret model

In the absence of an adequate small animal model for testing the efficacy of adenovirus-vectored respiratory syncytial virus (RSV) vaccines, a ferret model was established for this purpose. Recombinant adenovirus types 4, 5 and 7 expressing the RSV fusion glycoprotein (F), the attachment glycoprotein (G) or both F and G were constructed previously. These recombinants contain a deletion of a large portion of the E3 region of the respective adenovirus vector. In addition, an Ad7(E3+)F recombinant virus which contains an intact E3 region was constructed to assess whether E3 region functions might enhance vaccine immunogenicity. Evaluation of these viruses in the ferret model demonstrated that Ad4 and Ad5 recombinants, administered intranasally to ferrets, induce stronger seroresponses to RSV than do Ad7 recombinant viruses. Ad7(E3+)F did not show enhanced immunogenicity relative to E3-deleted recombinant viruses. However, measurement of RSV infectivity in nasal washes, following intranasal RSV challenge, showed that five different vaccination regimens, Ad7F/Ad4F, Ad7G/Ad4G, Ad7FG/Ad4FG, Ad4F/Ad7(E3+)F and Ad5F/Ad4F, protected ferrets from RSV infection in a dose-dependent manner.

Immunogenicity of recombinant adenovirus-respiratory syncytial virus vaccines with adenovirus types 4, 5, and 7 vectors in dogs and a chimpanzee

Recombinant adenovirus type 4, 5, and 7 expressing the fusion glycoprotein (F) gene, the attachment glycoprotein (G) gene, or both F and G genes of respiratory syncytial virus (RSV) was constructed. Intratracheal immunization of dogs with Ad7F induced moderate titers of RSV-neutralizing antibodies. After booster immunization with Ad4F, the dogs developed high titers of RSV-specific antibody. Subsequently, three two-dose vaccination regimens, Ad4F/Ad5F, Ad7G/Ad4G, and Ad7FG/Ad4FG, were compared with Ad7F/Ad4F for immunogenicity and protective efficacy. The results indicated that Ad4F/Ad5F was equal or greater in immunogenicity to Ad7F/Ad4F, but Ad7G/Ad4G and Ad7FG/Ad4FG were less effective than Ad7F/Ad4F in inducing RSV-neutralizing antibody. All vaccination regimens completely protected the lungs of dogs from RSV infection. A chimpanzee was sequentially immunized orally with Ad7F, Ad4F, and Ad5F. A low-level antibody response to RSV was induced after the primary immunization, but no significant increases were observed after booster immunizations.

Adenovirus vectors for gene expression

Adenoviruses possess a combination of features that make them highly suitable as vectors for expression of heterologous genes. Non-conditional and non-defective adeno-vectors have been constructed to obtain high level expression of a number of foreign genes and some of them have been shown in animal models to exhibit excellent promise as vaccine candidates.

A precore-defective mutant of hepatitis B virus associated with e antigen-negative chronic liver disease

The pathogenesis of chronic liver disease (CLD) due to persistent hepatitis B virus (HBV) infection has not been defined, but the disease activity is believed to correlate with the presence of hepatitis B e-antigen (HBeAg) antigenemia and high viremia. The molecular characterization of an HBV mutant isolated from an HBeAg-negative patient with severe CLD required amplification of the circulating HBV DNA (2 pg/ml) by the polymerase chain reaction (PCR). Direct sequencing of the nucleotides from five independent amplifications of the conserved precore region consistently revealed a G to A mutation in each of the two terminal codons of the precore region. Codon 28 was mutated from tryptophan-encoding TGG to a translational stop codon, TAG; codon 29 preceding the core initiation codon was changed from GGC to GAC. For biologic evaluation of these mutations on HBV replication and expression of HBeAg in vitro, HepG2 cells were transfected with cloned, recircularized mutant HBV DNA. The transfected cells contained subviral core particles in the cytoplasm and secreted mature HBV, without HBeAg, into the medium. The findings present the first evidence that complete HBV genomes can be amplified by PCR and are replication-competent in vitro. The data also indicate that HBeAg is not necessary for replication of HBV and furthermore suggest that HBeAg is not required for the progression of HBV-induced CLD.

Molecular characterization of a new variant of hepatitis B virus in a persistently infected homosexual man

Based on the diversity of nucleotide sequences of cloned hepatitis B virus DNA genomes, we have predicted possible replication of genetic variants of human hepatitis B virus. This prediction is exemplified by studies of a chronic carrier of HBsAg/adw2, who lacked anti-HBc but carried exceedingly high levels of hepatitis B virus DNA in serum. Molecular characterization of a number of clones revealed a restriction map that deviated significantly from the typical pattern of the adw2 subtype, especially around the EcoRI site commonly used as a reference point. Mutations appearing consistently in the precore and core regions included (a) mutation in the precore region resulting in a termination codon after the initiation codon, (b) mutation of the core initiation codon and (c) an inframe insert of 36 nucleotides in the precore region with a new initiation site for the core protein. The 36-nucleotide insertion resulted in a new core protein with 12 extra amino acids at its amino-terminal end. A few scattered point mutations were clustered in the amino-terminal half of the core gene. Although the core protein of this hepatitis B virus variant carried immunologically detectable HBcAg, the absence of a humoral immune response to HBcAg could have been caused by previous infection with human immunodeficiency virus. This naturally occurring human hepatitis B virus variant replicated efficiently without expressing the precore region, confirming previous observations made of the artificial mutants of duck hepatitis B virus.

Functional dissection of adenovirus VAI RNA

During the course of adenovirus infection, the VAI RNA protects the translation apparatus of host cells by preventing the activation of host double-stranded RNA-activated protein kinase, which phosphorylates and thereby inactivates the protein synthesis initiation factor eIF-2. In the absence of VAI RNA, protein synthesis is drastically inhibited at late times in infected cells. The experimentally derived secondary structure of VAI RNA consists of two extended base-paired regions, stems I and III, which are joined by a short base-paired region, stem II, at the center. Stems I and II are joined by a small loop, A, and stem III contains a hairpin loop, B. At the center of the molecule and at the 3' side, stems II and III are connected by a short stem-loop (stem IV and hairpin loop C). A fourth, minor loop, D, exists between stems II and IV. To determine sequences and domains critical for function within this VAI RNA structure, we have constructed adenovirus mutants with linker-scan substitution mutations in defined regions of the molecule. Cells infected with these mutants were analyzed for polypeptide synthesis, virus yield, and eIF-2 alpha kinase activity. Our results showed that disruption of base-paired regions in the distal parts of the longest stems, I and III, did not affect function, whereas mutations causing structural perturbations in the central part of the molecule containing stem II, the proximal part of stem III, and the central short stem-loop led to loss of function. Surprisingly, one substitution mutant, sub742, although dramatically perturbing the integrity of the structure of this central portion, showed a wild-type phenotype, suggesting that an RNA with an alternate secondary structure is functional. On the basis of sensitivity to single-strand-specific RNases, we can derive a novel secondary structure for the mutant RNA in which a portion of the sequences may fold to form a structure that resembles the central part of the wild-type molecule, which suggests that only the short stem-loop located in the center of the molecule and the adjoining base-paired regions may define the functional domain. These results also imply that only a portion of the VAI RNA structure may be recognized by the host factor(s).

Enzymatic amplification of hepatitis B virus DNA in serum compared with infectivity testing in chimpanzees

The in vivo infectivity titration of hepatitis B virus (HBV) has been biologically standardized in terms of chimpanzee infectious dose (CID50). The polymerase chain reaction (PCR) was used for in vitro enzymatic amplification of HBV DNA and comparison with CID50. Serial dilutions of human serum specimens containing HBV adw (CID50 10(-7] and ayw (CID50 10(-7.5] were tested to determine the reproducibility and sensitivity of PCR for the detection of HBV DNA. The detection limit of HBV DNA in serum using PCR was 10(-8) for either amplification of HBV DNA extracted from serum or direct amplification of HBV DNA in proteolyzed serum. The amplification efficiency of PCR in proteolysates was not significantly reduced by using a 0.25% concentration (vol/vol) of nonionic detergents and 2.5% concentration (vol/vol) of digested human serum. Thus, PCR is a specific and rapid method for in vitro detection of HBV DNA that is more sensitive than the in vivo infectivity titration of HBV by chimpanzee inoculation. Therefore, if HBV-related DNA cannot be detected by PCR in specimens or biologic products, they probably do not contain infectious HBV.

Efficient expression of small RNA polymerase III genes from a novel simian virus 40 vector and their effect on viral gene expression

In the past, simian virus 40 (SV40) has been used as a cloning vehicle to clone foreign genes by substituting portions of the viral genome vital for viral replication. Propagation of these defective viruses required a helper virus and the recombinant viruses obtained could be grown only as a mixture. In this study, we describe a novel nondefective SV40 vector to clone small RNA polymerase III genes. Two small RNA polymerase III genes, an amber suppressor human serine tRNA gene and the adenovirus (Ad) VAI RNA gene, were cloned in the intron region of the large-T antigen gene of SV40 after deleting DNA sequences coding for the small-t polypeptide. The recombinant viruses grew to wild type levels and showed no growth defects. When CV-1p cells were infected with these viruses, the cloned RNA polymerase III genes were expressed at high levels at late times. Interestingly, large amounts VAI RNA in CV-1p cells infected with SV40-VA recombinant virus, did not enhance translation of viral mRNAs significantly but did lead to a 3 to 4 fold increase in the steady state levels of large-T mRNA suggesting a novel function for VAI RNA in SV40 infected monkey cells. Furthermore, VAI mutants which fail to function in Ad infected human cells also failed to enhance the levels of large-T mRNAs in monkey cells infected with SV40. The simple SV40 vector described here may be useful to study the structure and function of small RNA polymerase III genes in the context of a eucaryotic chromosome. In addition, the nondefective recombinant SV40 which expresses the suppressor tRNA gene at high levels may provide a useful helper system to propagate animal viruses with amber mutations in essential genes.

Suppression of the translation defect phenotype specific for a virus-associated RNA-deficient adenovirus mutant in monkey cells by simian virus 40

Human cells infected with adenovirus type 2 (Ad2) or Ad5 require VAI RNA for efficient translation of viral mRNAs at late times after infection. The Ad5 mutant dl-sub720 synthesized neither virus-associated I (VAI) nor VAII RNAs, and infection of human cells with this mutant resulted in reduced virion polypeptide synthesis. Infection of monkey cells with this mutant also resulted in drastic reduction of polypeptide synthesis compared with wild-type (WT) adenovirus infections. Steady-state levels of hexon-specific mRNA were found to be comparable in WT- and mutant-infected monkey cells. The in vitro translation experiments showed that double-mutant- and WT-infected cells contained comparable levels of translatable hexon mRNA (and other adenovirus late mRNAs), suggesting that the severe inhibition of hexon protein synthesis in the VA mutant involves a translation block. Preinfection of monkey cells with simian virus 40 fully restored the efficient translation of this mRNA in the VA mutant infections to the level observed in WT-infected cultures. These results raise the possibility that simian virus 40 may encode or induce factors that suppress the translation block that occurs during adenovirus infections in the absence of the VA RNAs.

Construction and analysis of additional adenovirus substitution mutants confirm the complementation of VAI RNA function by two small RNAs encoded by Epstein-Barr virus

Adenovirus VAI RNA is essential for the efficient initiation of translation of viral mRNAs at late times after infection. Recently, by constructing an adenovirus type 5 substitution mutant, we showed that the Epstein-Barr virus encoded two small RNAs complemented for the VAI RNA function in the adenovirus type 5 lytic growth (Bhat and Thimmappaya, Proc. Natl. Acad. Sci. USA 80:4789-4793, 1983). This observation was based on our inability to propagate an adenovirus type 5 mutant lacking functional VAI and VAII genes. Subsequently, it was found that this mutant was viable and able to grow to a low titer. Therefore, we examined the complementation of the VAI RNA function by the Epstein-Barr virus-encoded RNAs by constructing additional adenovirus type 5 substitution mutants containing multiple copies of the Epstein-Barr virus-encoded RNA genes in nonessential early transcriptional region III. The new substitution mutants synthesized viral polypeptides at late times at levels comparable to those observed in wild type-infected cells. Our results convincingly demonstrated that the two Epstein-Barr virus-encoded RNAs can efficiently complement for the VAI RNA-mediated translational defect in adenovirus-infected cells.

Structural requirements of adenovirus VAI RNA for its translation enhancement function

Recently, by genetic and biochemical approaches, it has been shown that adenovirus VAI RNA is required for efficient translation of viral mRNAs at late times after infection. To understand the nucleotide sequences and the domains of the VAI RNA that are responsible for the role of VAI RNA in enhancement of translation, a mutational analysis of the VAI gene was undertaken. Deletion, substitution, and insertion mutations covering most of the nucleotide sequences of VAI RNA were introduced into the VAI gene at the plasmid level. These mutant genes were then reintroduced into the virus, and growth properties of the mutant viruses were studied. The majority of the mutants retained normal or nearly normal levels of biological function. Mutations in the region between +43 and +53 and between +107 and the 3' end of the gene resulted in a considerable loss of activity. These mutants, however, grew significantly better than did an adenovirus type 5 mutant lacking both functional VAI and VAII genes, indicating that they retain a portion of their activity. Because no one mutation was able to completely abolish the function, we suggest that the VAI RNA may have multiple functional sites for its translation modulation function. These multiple sites may be short oligonucleotide sequences that may interact with cellular or viral components or both during translation.

Adenovirus mutants with DNA sequence perturbations in the intragenic promoter of VAI RNA gene allow the enhanced transcription of VAII RNA gene in HeLa cells

Ad2 VAI gene strongly competes for transcription with VAII gene in vitro. It has been suggested that this competition may be a basis for the large excess of VAI gene transcription in virus infected cells at late times. We have studied the effect of the DNA sequence perturbations of the intragenic promoter of the VAI gene on transcription of VAII gene at the level of viral chromosome. Several Ad5 mutants with mutations in the promoter of VAI gene were constructed and transcription of their VAI and VAII genes were analyzed in the infected cells. It was found that transcription of VAII gene increased dramatically when either Box A or Box B promoter sequences of VAI gene were mutated or when the entire VAI gene was replaced by a DNA segment with an unrelated DNA sequence. Thus, at late times, active transcription of VAI gene appears to partially repress transcription of VAII gene. Those mutants which synthesized large quantities of VAII RNA only grew more slowly yielding a titer which was 1/10 of that of their parent but 5 to 6 fold higher than that of an Ad5 mutant lacking both VAI and VAII genes.

Organization of the noncontiguous promoter components of adenovirus VAI RNA gene is strikingly similar to that of eucaryotic tRNA genes

The intragenic transcriptional control region (internal promoter) of the adenovirus type 2 VAI RNA gene was mutated by deletion, insertion, and substitution of DNA sequences at the plasmid level. The mutant plasmids were assayed for in vitro transcriptional activity by using HeLa cell extracts. The mutant clones with substitution or insertion of DNA sequences or both between nucleotides +18 and +53 of the VAI RNA gene were all transcriptionally active, although to various extents. Substitution of unrelated DNA sequences up to +26 or between +54 and +61 abolished the transcriptional activity completely. Based on these results, the intragenic promoter sequences of the VAI RNA gene can be subdivided into two components: element A, +10 to +18; and element B, +54 to +69. The distance between the A and B components could be enlarged from its normal 35 base pairs to 75 base pairs without destroying the transcriptional activity. However, a deletion of 4 or 6 base pairs in the DNA segment separating the A and B components (segment C) reduced the transcriptional activity of the genes to less than 2% of that of the wild type. When the VAI RNA gene with its element A or B was substituted for the corresponding element A or B of the Xenopus laevis tRNAMet gene, the hybrid genes transcribed close to the level of the wild-type VAI RNA gene and about 10- to 20-fold more efficiently than the tRNAMet gene. Thus, the organization of DNA sequences in the internal promoter of the VAI RNA gene appears to be very similar to that of eucaryotic tRNA genes. This similarity suggests an evolutionary relationship of the VAI RNA gene to tRNA genes.

Two small RNAs encoded by Epstein-Barr virus can functionally substitute for the virus-associated RNAs in the lytic growth of adenovirus 5

Adenovirus (Ad) serotypes 2 and 5 synthesize large amounts of two low molecular weight RNAs designated virus-associated (VA) 1 and 2. Recently, genetic and biochemical approaches have been used to show that Ad2 VA1 RNA is required for efficient translation of viral mRNAs produced at late times after infection. Primate cells harboring the Epstein-Barr virus genome (EBV) synthesize large amounts of two low molecular weight RNAs: EBER1 and EBER2. Striking similarities of gene organization have been noted between the genes coding for Ad5 VA RNAs and the EBV EBERs [Rosa, M. D., Gottlieb, E., Lerner, M. R. & Steitz, J. A. (1981) Mol. Cell. Biol. 1, 785-796]. To examine whether the EBRs can functionally substitute for the VA RNAs for the lytic growth of Ad5, we have constructed an Ad5 substitution mutant in which the two VA RNA genes have been deleted and replaced by an EBV DNA segment coding for the two EBERs. The resulting Ad5 mutant synthesizes large amounts of the EBERs and is viable. Thus, two small RNAs of EBV origin, having primary and secondary structures different from those of the VA RNAs, can functionally substitute for the VA RNAs in the lytic growth of Ad5. These results are discussed in the context of mechanism of function of the VA RNAs.