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Biomedical subjects

T Lin

Publications and source records attributed to T Lin.

At least 19 recordsLinked to original sources

Prognostic significance of osteopontin in hepatitis B virus-related hepatocellular carcinoma.

BACKGROUND AND AIMS: Osteopontin (OPN) is known to be associated with metastasis in many types of cancers. Since OPN is a highly phosphorylated and glycosylated protein, the modification after transcription is very important to its function. In hepatocellular carcinoma (HCC), the elevated expression of OPN at mRNA levels and its relationship with metastasis and poorer prognosis of the patients have been reported. However, the prognostic impact of OPN at protein levels on the patients with hepatitis B virus (HBV)-related HCC after hepatectomy is still limited. PATIENTS AND METHODS: The expression of OPN was examined at protein level by using immunohistochemistry in 72 patients who underwent hepatectomy for HBV-related HCC, and its prognostic significance in disease-free and overall survival of the patients was also analyzed by log-rank test and multivariate Cox regression analyses. RESULTS: Thirty-nine of 72 (54.17%) HBV-related HCC specimens were positive for OPN with cytoplasmic staining. OPN was highly expressed in the specimens with capsular infiltration compared to those without (P<0.05), and also was significantly related with portal vein invasion (P<0.01) and lymph node invasion (P<0.01). The mean disease-free survival (DFS) was only 13.55+/-14.77 months when the HBV-related HCC specimens highly expressed OPN compared to 36.00+/-18.68 months for those with low expression (P<0.001). The overall survival (OS) of the patients was 18.63+/-17.28 months when the HCC over-expressed OPN compared to 42.59+/-16.85 months for HCC with the low expressed OPN (P<0.001). Multivariate analysis showed that OPN over-expression was the strongest independent adverse prognostic factor for both DFS (P=0.01) and OS (P=0.014). CONCLUSIONS: OPN over-expression was closely related to capsular infiltration, venous invasion, lymph node metastasis, and also with worse prognosis, suggesting that OPN might be deemed as a useful molecular marker for predicting the prognosis of HCC.

Adult↗

High frequency occurrence of 1-OPRD variant of PRNP gene in gastric cancer cell lines and Chinese population with gastric cancer.

The prion protein gene PRNP encodes PrPc and PrPsc, causing a number of neurological disorders. Approximately 10-15% of human prion disease is inherited and more than 20 pathogenic mutations have been found. Most of the genetic alterations are point mutations, with the exception of genetic insertions of one to nine extra octapeptide repeats occurring in the important octapeptide-coding region. Our previous work showed that PrPc was overexpressed in gastric cancer. We wondered whether mutations of PrPc existed in human gastric cancer. DNA sequencing and gel electrophoresis were used to determine the possible mutation of PrPc in patients and cell lines of gastric cancer. We found that 1-OPRD (one octapeptide-repeat deletion) homozygosity or heterozygosity exists in several gastric cancer cell lines, e.g. MKN28 and KatoIII are homozygous for 1-OPRD, and SGC7901 and BGC-823 are heterozygous for 1-OPRD. The mutation frequency in tissues of gastric cancer cases is significantly higher than that in the common population (p<0.05). All positive cases in gastric cancer were found to be heterozygous for 1-OPRD. Further study of the variant may be helpful in understanding the mechanisms of occurrence and development of clinical gastric carcinoma as well as the biology of the mysterious gene PRNP.

Adolescent↗

Alemtuzumab induces caspase-independent cell death in human chronic lymphocytic leukemia cells through a lipid raft-dependent mechanism.

Alemtuzumab is a humanized IgG1 kappa antibody directed against CD52, a glycosyl-phosphatidylinositol linked cell-membrane protein of unknown function. Herein, we demonstrate that alemtuzumab promotes rapid death of chronic lymphocytic leukemia (CLL) cells in vitro, in a complement and accessory cell free system. Using minimal detergent solubilization of CLL membranes, we found that CD52 colocalizes with ganglioside GM-1, a marker of membrane rafts. Fluorescence microscopy revealed that upon crosslinking CD52 with alemtuzumab+anti-Fc IgG, large patches, and in many cases caps, enriched in CD52 and GM-1 formed upon the CLL cell plasma membrane. Depletion of membrane cholesterol or inhibition of actin polymerization significantly diminished the formation of alemtuzumab-induced caps and reduced alemtuzumab-mediated CLL cell death. We compared alemtuzumab-induced direct cytotoxicity, effector cell-mediated toxicity and complement-mediated cytotoxicity of CLL cells to normal T cells. The direct cytotoxicity and observed capping was significantly greater for CLL cells as compared to normal T cells. Cell-mediated and complement-mediated cytotoxicity did not significantly differ between the two cell types. In summary, our data support the hypothesis that alemtuzumab can initiate CLL cell death by crosslinking CD52-enriched lipid rafts. Furthermore, the differential direct cytotoxic effect suggests that CD52 directed antibodies could possibly be engineered to more specifically target CLL cells.

Actins↗

Skin colonization by Staphylococcus aureus in patients with eczema and atopic dermatitis and relevant combined topical therapy: a double-blind multicentre randomized controlled trial.

BACKGROUND: Staphylococcus aureus has a peculiar ability to colonize the skin of patients with eczema and atopic dermatitis (AD), and is consistently found in eczematous skin lesions in these patients. A correlation between the severity of the eczema and colonization with S. aureus has been demonstrated, and it has been determined that bacterial colonization is an important factor aggravating skin lesions. Patients colonized with S. aureus have been treated with antibiotics in several open and double-blind placebo-controlled studies, with conflicting results. OBJECTIVES: To investigate the colonizing features of S. aureus in the lesional and nonlesional skin of patients with eczema and AD in China and to compare the therapeutic effect of mupirocin plus hydrocortisone butyrate with vehicle ointment plus hydrocortisone butyrate. METHODS: A multicentre, double-blind randomized trial was conducted. Eczema Area and Severity Index (EASI) scores were evaluated before the start of the trial and on the 7th, 14th and 28th day of treatment. Swabs for bacterial isolation were taken from lesional skin before the start of the trial and on the 7th, 14th and 28th day of treatment, and from nonlesional skin only before the start of the trial. A combination topical therapy with mupirocin plus hydrocortisone butyrate ointment was used in the experimental group, with vehicle ointment plus hydrocortisone butyrate ointment as a control. RESULTS: Of 327 patients enrolled in the study, 208 had eczema and 119 had AD. Bacteria were isolated from 70.2% of lesional and 32.7% of nonlesional skin samples from patients with eczema, of which S. aureus accounted for 47.3% and 27.9%, respectively. Bacteria were isolated from 74.8% of lesional and 34.5% of nonlesional skin samples from patients with AD, of which S. aureus accounted for 79.8% and 80.5%, respectively. The colonization density of S. aureus was markedly higher in lesional than in nonlesional skin, both in patients with eczema and with AD (P < 0.01, P < 0.05), and was positively correlated with lesion severity. Considering the EASI scores before and after treatment and the final effective rate, good therapeutic effects were obtained in both the combination experimental groups and the control groups (P < 0.01), and there were no differences in the global therapeutic effect between the two groups in patients with eczema and with AD (P > 0.05). However, in patients with eczema with a clinical score of > 8 or in patients with AD with a clinical score of > 7, the therapeutic effect in the experimental groups was superior to that in the control groups (P < 0.05) on the 7th day of treatment. There were no differences between the two groups on the 14th and 28th days of treatment (P > 0.05). Following the improvement of symptoms and signs of eczema and AD, the positive rates of bacteria and S. aureus were reduced on the 7th day of treatment. CONCLUSIONS: This study confirmed that lesional skin of patients with eczema and AD was more frequently colonized with S. aureus than was nonlesional skin. The more severe the eczema, the higher the colonization rate of S. aureus, and S. aureus was also more often present in lesional and nonlesional skin in patients with AD than in those with eczema. Staphylococcus aureus infection is related to the pathogenesis of eczema and AD. An antibiotic-corticosteroid combination and corticosteroid alone both gave good therapeutic effect in eczema and in AD, and both reduced colonization by S. aureus. Early combined topical therapy is beneficial to patients with moderate to severe eczema and AD, and it is unnecessary to use antibiotics at later stages of disease or in mild eczema or AD.

Adolescent↗

Enhanced immunogenicity and antitumour effects with heterologous prime-boost regime using vaccines based on MG7-Ag mimotope of gastric cancer.

MG7-Ag, gastric cancer-associated antigen, has been shown to be immunogenic and has been used as marker molecule for prognosis. In a previous study, we developed an oral DNA vaccine based on MG7-Ag mimotope. However, we failed to detect cellular immune response using the oral MG7-Ag mimotope DNA vaccine. To induce significant T cell response, we developed a recombinant adenovirus vaccine based on MG7-Ag mimotope and evaluated the efficacy and protective effects of heterologous prime-boost immunization protocol with an oral DNA vaccine previously developed. We found that both vaccines were able to elicit a significant humoral response against MG7-Ag, while the highest serum titre MG7 antibody was detected in mice immunized with the heterologous prime-boost immunization protocol. Enzyme-linked immunospot (ELISPOT) assay demonstrated that the heterologous prime-boost immunization strategy was more efficient in inducing T cell response than the homologous prime-boost strategy. In the tumour challenge assay, 2 of 5 mice immunized with the heterologous prime-boost protocol were tumour free, while none of the mice in homologous prime-boost groups or control groups was tumour free. Those tumour-bearing mice in the heterologous prime-boost regime had smaller tumour masses than their counterparts in the homologous prime-boost groups or control groups. Therefore, our study suggests that vaccines against MG7-Ag induce significant immune response against gastric cancer, and that the heterologous prime-boost protocol using different types of vaccines could achieve better protective effect than the homologous prime-boost protocol.

Adenoviridae↗

Influence of condensed sweet cream buttermilk on the manufacture, yield, and functionality of pizza cheese.

Compositional changes in raw and pasteurized cream and unconcentrated sweet cream buttermilk (SCB) obtained from a local dairy were investigated over 1 yr. Total phospholipid (PL) composition in SCB ranged from 0.113 to 0.153%. Whey protein denaturation in pasteurized cream over 1 yr ranged from 18 to 59%. Pizza cheese was manufactured from milk standardized with condensed SCB (approximately 34.0% total solids, 9.0% casein, 17.8% lactose). Effects of using condensed SCB on composition, yield, PL recovery, and functional properties of pizza cheese were investigated. Cheesemilks were prepared by adding 0, 2, 4, and 6% (wt/wt) condensed SCB to part-skim milk, and cream was added to obtain cheesemilks with approximately 11.2 to 12.7% total solids and casein:fat ratio of approximately 1. Use of condensed SCB resulted in a significant increase in cheese moisture. Cheese-making procedures were modified to obtain similar cheese moisture contents. Fat and nitrogen recoveries in SCB cheeses were slightly lower and higher, respectively, than in control cheeses. Phospholipid recovery in cheeses was below 40%. Values of pH and 12% trichloro-acetic acid-soluble nitrogen were similar among all treatments. Cheeses made from milk standardized with SCB showed less melt and stretch than control cheese, especially at the 4 and 6% SCB levels. Addition of SCB significantly lowered free oil at wk 1 but there were no significant differences at wk 2 and 4. Use of SCB did not result in oxidized flavor in unmelted cheeses. At low levels (e.g., 2% SCB), addition of condensed SCB improved cheese yield without affecting compositional, rheological, and sensory properties of cheese.

Caseins↗

Use of transoesophageal echocardiography during cardiac arrest in patients undergoing elective non-cardiac surgery.

BACKGROUND: Sudden unexpected intraoperative cardiac arrests in patients undergoing elective non-cardiac operations are rare but catastrophic complications. The efficacy and utility of transoesophageal echocardiography (TOE) in the diagnosis and management of these events have not been reported earlier. METHODS: Unexpected intraoperative cardiac arrests in patients undergoing elective non-cardiac operations were prospectively studied during a 6 yr period. In these patients, TOE was performed within 5 min after initiation of external chest compression to identify the causes of the cardiac arrests. RESULTS: Among a total of 125 965 surgical operations, 10 patients who suffered intraoperative cardiac arrests were studied. The causes of the cardiac arrests including myocardial infarction in five, pulmonary embolism in two, and severe hypovolaemia and ventricular arrhythmia without specific pathology in the other two patients were correctly identified using TOE. Seven patients survived. CONCLUSION: We conclude that TOE was useful in cardiac arrest during non-cardiac surgery for identifying or excluding pulmonary embolism and for directing investigations and treatment in those patients who had suffered myocardial infarction.

Adult↗

High-dose busulfan, cyclophosphamide, and etoposide does not improve outcome of allogeneic stem cell transplantation compared to BuCy2 in patients with acute myeloid leukemia.

SUMMARY: To reduce relapse following allogeneic transplantation for AML, intensification of high-dose busulfan/cyclophosphamide using additional agents has been investigated but with few reported comparisons. We compared an intensified regimen of etoposide (60 mg/kg), busulphan (14 mg/kg), and cyclophosphamide (120 mg/kg) (BuCyVP) with BuCy2 in 237 AML patients. No significant difference in overall outcome was observed following BuCyVP (n=127) or BuCy2 (n=110). The 5-year survival was 27.3 and 30.1% following BuCyVP and BuCy2, respectively (P=0.48). Similarly, the 5-year cumulative incidence of relapse (CIR) was 28.3 and 34.8% with BuCyVP and BuCy2 (P=0.45), respectively. On multivariable analysis, patients transplanted in CR1 (P=0.002) and from related donors (P=0.013) had longer survival, while disease status at transplant was the only factor predicting CIR (P=0.002). In a separate analysis of CR1 patients (n=56), there was no significant difference in survival (P=0.37) or CIR (P=0.87) between the two regimens. However, for more advanced disease, there was a trend towards less relapse with BuCyVP (P=0.08), which was balanced by a higher cumulative incidence of transplant-related deaths (P=0.03) compared to BuCy2, resulting in similar survival. Overall, our results do not support the use of the more intensive BuCyVP regimen over BuCy2 in either early or more advanced disease AML patients.

Acute Disease↗

Excess propagation and biological control of zooplanktonic Cyclops in drinking water sources.

Starting with the occurrence of Cyclops in drinking water sources and its danger to drinking water safety, we extensively investigated the nature of its excess propagation by analyzing the effect of living space and predator pressure in the food chain on its survival. Then we developed an ecological project using fish biomanipulation, different to the conventional fishery culture technique, to control excess propagation of Cyclops. The control effects on Cyclops of four species of fish were investigated experimentally at a stocking density of 30 g/m3 of water. Results showed that the food habit of the fish had a significant influence on the biological control of Cyclops. The propagation of Cyclops could be controlled effectively and also the water quality improved simultaneously by stocking filter-feeding fish, such as silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). However, herbivorous Ctenopharyngodon idellus and omnivorous Cyprinus carpio had no obvious biological effects on controlling the growth of Cyclops and restoring water quality. The results further proved that under conditions of proper poly-culture densities of silver carp and bighead carp, the number of Cyclops might be controlled at very low levels and eutrophication might be abated by removing nutrients from the water body.

Animals↗

Therapy-related myelodysplasia and leukemia occur infrequently following VP-16 priming and autotransplantation without total body irradiation.

The use of VP-16 for stem cell mobilization has been cited as a significant risk factor for the development of therapy-related myelodysplasia/leukemia (tMDS/tAML) following autologous transplantation. The present study analyzed a large cohort of patients who underwent autotransplantation following stem cell mobilization with VP-16 and radiation-free preparation in order to determine the risk of tMDS/tAML. The estimated incidence of 9.9% at 7 years suggests that in the absence of TBI, VP-16 priming is not associated with an increased incidence of tMDS/tAML.

Adolescent↗

Impact of the high-risk and mass strategies on hypertension control and stroke mortality in primary health care.

Stroke has been the second leading cause of death in Taiwan in recent years. Following a 6-month pilot study in Yu-Chi in 1993, a 3.5-year hypertension control programme was performed to examine the effectiveness of combined high-risk and mass strategies in a rural community with limited medical resources. All Yu-Chi residents aged 40 years and older were invited to participate in the programme. The high-risk strategies included hypertension screening, home visits, and follow-up for the hypertensives. The mass strategies included health education and village-based campaigns. Changes over time in the participants' hypertension knowledge, behaviour, and blood pressure control status were evaluated. A comparison of the stroke mortality between the intervention community and a neighbourhood reference community before and after the intervention programme was performed. A total of 4977 residents were screened and 3761 completed the first and second rescreening. The hypertension knowledge and behaviour scores in the hypertensives significantly improved, systolic and diastolic blood pressure and waist-to-hip ratio significantly reduced, and the rates of hypertension treatment and control increased significantly at 1 and 3.5 years after intervention. In contrast, blood pressure levels increased significantly in the normotensives. Between 1994 and 1997, stroke mortality rate decreased by 39.9 and 4.8% in the intervention and reference communities, respectively. The results indicated that the community-based hypertension control programme was effective. The immediate decline in stroke mortality appeared to be mostly related to the high-risk strategies.

Adult↗

An enzootic transmission cycle of Lyme borreliosis spirochetes in the southeastern United States.

Lyme borreliosis, or Lyme disease (LD), is a tick-borne zoonotic infection of biomedical significance, caused by Borrelia burgdorferi sensu lato (s.l.) spirochetes and transmitted by Ixodes species ticks. It usually circulates among wildlife vertebrate reservoirs and vector ticks but may infect humans, causing multisystem problems. In far western and northern North America, the host reservoirs, tick vectors, and genospecies of Borrelia are well known but not so in the southern U.S., where there is controversy as to the presence of "true" LD. Here we report the presence of the LD spirochete B. burgdorferi sensu stricto (s.s.) and Borrelia bissettii, three main reservoir hosts, and two enzootic tick vectors in the southeastern U.S. The two enzootic tick vectors, Ixodes affinis and Ixodes minor, rarely bite humans but are more important than the human biting "bridge" vector, Ixodes scapularis, in maintaining the enzootic spirochete cycle in nature. We also report extraordinary longevities and infections in the reservoir rodents Peromyscus gossypinus, Sigmodon hispidus, and Neotoma floridana.

Animals↗

Radiation-free regimens result in similar outcomes of allogeneic hematopoietic progenitor cell transplantation in patients aged >or=50 years compared to younger adults with low-risk disease.

Age >or=50 years has been reported to be an adverse risk factor for allogeneic BMT, and consequently many of these patients are either not transplanted or treated on nonmyeloablative protocols. To study if older patients perform poorly relative to younger adults following myeloablative allogeneic transplants, we compared the outcomes of consecutive adults aged >or=50 years (n=51) to those <50 years (n=262) who received BU, CY+/-etoposide and allogeneic transplantation for AML, CML, MDS and NHL from 1984 to 2000. Median ages were 53 (range 50-66) and 35 (range 18-49) years for older and younger patients, respectively. Patients were low-risk if they had AML in CR1, CML in first chronic phase, refractory anemia, or NHL in remission or sensitive relapse at the time of transplantation. All others were high-risk. In patients with low-risk disease, there was no significant difference in overall survival (OS) between older and younger adults (P=0.64), while older patients tended to have a shorter OS among high-risk patients (P=0.06). The 3-year OS was 53% (95% CI, 29-77%) compared to 60% (95% CI, 50-69%) for older and younger patients with low-risk disease, respectively. The corresponding 3-year OS were 27% (95% CI, 11-43%) and 37% (95% CI, 25-45%) for high-risk patients. In low-risk patients, the incidence of acute and chronic graft-versus-host disease, and treatment-related mortality were similar in older and younger patients, while older patients experienced more treatment-related deaths by day 100. On multivariable analysis, age >or=50 years was a significant adverse factor only when high-risk patients were considered. We conclude that when radiation-free conditioning is used, age >or=50 years is not a significant adverse risk factor for allogeneic BMT in patients with low-risk disease, and that such patients should not be excluded from conventional myeloablative approaches until the efficacy of nonmyeloablative transplantation is better established.

Adolescent↗

Effects of antioxidative agents on apoptosis induced by ischaemia-reperfusion in rat intestinal mucosa.

BACKGROUND AND AIM: We have previously demonstrated that ischaemia-reperfusion induces apoptosis in the intestinal mucosa. To evaluate that reactive oxygen species enhanced intestinal apoptosis after ischaemia-reperfusion, we examined whether antioxidants reduced apoptosis. METHODS: Rats were infused through a duodenal tube with antioxidative agents, glutathione, rebamipide and dymethylsulfoxide during 2 h before an ischaemic insult. The superior mesenteric artery was occluded for 60 min, followed by 60 min reperfusion. Apoptosis was evaluated by percentage fragmented DNA (fragmented DNA/total DNA) and immunochemical staining. RESULTS: Increase in apoptosis in the intestinal mucosa after ischaemia-reperfusion was attenuated by intraduodenal infusion of antioxidative agents, but was not completely abolished. CONCLUSION: Scavenging effects of the antioxidative agents attenuated increases in intestinal apoptosis, indicating that oxidative stress after ischaemia-reperfusion plays an important role in induction of apoptosis in the intestinal mucosa.

Alanine↗

The role of the cytoskeleton in capacitative calcium entry in myenteric glia.

Capacitative calcium entry (CCE) is the process by which intracellular calcium is replenished from the external milieu upon depletion of intracellular stores. CCE is thought to participate in chemotaxis, proliferation and cell signalling. A physical interaction between intracellular stores and the plasma membrane is postulated to regulate CCE. We hypothesized that cytoskeletal disruption alters this interaction, inhibiting CCE in enteric glia. Cultured myenteric glia from neonatal guinea-pigs were treated with cytochalasin D (10 micro mol L-1), a microfilament disrupting agent, nocodazole (20 micro mol L-1), a microtubule disrupting agent, or vehicle (dimethyl sulphoxide). Intracellular calcium changes were measured using fura-2 microfluorimetry. To evaluate the rate of cation re-entry, barium was substituted for calcium because barium is not sequestered internally. Cytochalasin D-treated glia had diminished CCE responses (57 +/- 3 nmol L-1) compared with controls (97 +/- 7 nmol L-1) as did nocodazole-treated glia (30 +/- 2 nmol L-1) vs controls (77 +/- 6 nmol L-1). The proportion of cells demonstrating CCE abolition was greater in the cytochalasin (50 +/- 8%) and nocodazole-treated (89 +/- 2%) groups compared with controls (21 +/- 2%, 40 +/- 9%, respectively). Cytochalasin D and nocodazole treatment diminished the rate of cation re-entry based on diminished barium entry in treated vs control cells. From this study, we conclude that disruption of cytoskeletal elements diminishes calcium influx essential to calcium store repletion in myenteric glia.

Animals↗

Expression and regulation of glucose transporter 8 in rat Leydig cells.

Basal and LH/human chorionic gonadotropin (hCG)-stimulated testosterone formation by Leydig cells is dependent on ambient glucose levels. Inhibition of glucose uptake is associated with decreased testosterone formation. Recently, glucose transporter 8 (GLUT8) has been shown to be highly expressed in the testis. In the present study, we have investigated the expression and regulation of the GLUT8 gene in rat Leydig cells. Primers were designed by using sequences that are not conserved in GLUT1 to GLUT5 and that contain the glycosylation region of GLUT8. This yielded an amplicon of 186 bp. The tIssue-specific expression experiments in adult rat (55- to 65-day-old) tIssues revealed that GLUT8 is expressed predominantly in the testis, in smaller amounts in heart and kidney, and in negligible amounts in liver and spleen. Furthermore, GLUT8 mRNA was found to be highly expressed in crude interstitial cells, Leydig cells and testicular and epididymal germ cells. In prepubertal rat (20-day-old) tIssues, GLUT8 expression was comparatively much lower than in the adult rat tIssues. By comparative RT-PCR, hCG caused dose- and time-dependent increases of GLUT8 mRNA levels. hCG and IGF-I had synergistic effects on GLUT8 mRNA and protein expression. GLUT1 and GLUT3 were also found to be expressed in Leydig cells. However, neither GLUT1 nor GLUT3 were affected by treatments with hCG, IGF-I or hCG and IGF-I combined. The addition of murine interleukin-1alpha (mIL-1alpha; 10 ng/ml), murine tumor necrosis factor-alpha (mTNF-alpha; 10 ng/ml), murine interferon-gamma (mIFN-gamma; 500 U/ml) separately or in combination decreased hCG-induced GLUT8 mRNA levels significantly. In conclusion, GLUT8 mRNA in Leydig cells was positively regulated by hCG and IGF-I and down-regulated by cytokines, mIL-1alpha, mTNF-alpha and mIFN-gamma. These results indicate that hCG, growth factors and cytokines affect Leydig cell steroidogenesis by modulating GLUT8 expression.

Animals↗

Evolutionary and taxonomic implications of conserved structural motifs between picornaviruses and insect picorna-like viruses.

A comparison of the recently determined structure of an insect picorna-like virus, Cricket paralysis virus (CrPV), with that of the mammalian picornaviruses shows that several structural features are highly conserved between these viruses. These conserved features include the topology of the coat proteins, the conformation of most loops, and the general arrangement of the internally located N-terminal arms of the coat proteins. The conformational conservation of the N-termini of the three major coat proteins between CrPV and the picornaviruses suggests a putative ancestral T = 3 virus. Comparisons of the genome structure and amino-acid sequence of the coat proteins of CrPV with a number of other insect picorna-like viruses show that most of them belong to a novel group, recently given the interim name Cricket paralysis-like viruses. Two other insect picorna-like viruses, Infectious flacherie virus (IFV) and Sacbrood virus (SBV), for which the genome sequences have recently been determined, have very different coat protein sequences and a genome organization more like the picornaviruses. However, the position of the small VP4 protein in the structural protein polyprotein as well as the mechanism for its cleavage from VP3 upon assembly strongly suggests an evolutionary link to the "Cricket paralysis-like viruses". We propose that the picornaviruses, Cricket paralysis-like viruses and IFV/SBV group are a natural assemblage. The ancestor for this assemblage had a structure based upon the CrPV/picornavirus paradigm and a genome encoding a single major coat protein; gene duplication and rearrangements have subsequently produced the viruses that we observe today. We also discuss the possible relatives of the proposed assemblage and the likely implications of future structural studies that may be carried out on the putative relatives.

Amino Acid Motifs↗