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R L Thompson

Publications and source records attributed to R L Thompson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Novel quantitative assays for estimating the antimicrobial activity of fresh garlic juice.

Novel agar diffusion and broth dilution assays were developed for quantitatively estimating the antimicrobial activity of fresh garlic juice. Bacteria found to be inhibited by garlic juice in agar diffusion assay included two gram-positive and five gram-negative species. Leuconostoc mesenteroides was not inhibited. Escherichia coli B-103 (HB101, with pJH101, ampicillin resistant, 100 microg ml(-1)) was inhibited and chosen as the standard culture for quantitative assays. The agar diffusion assay was based on the slope ratio method, where the slope of dose response for garlic juice was divided by the slope of dose response for methylmethane thiosulfonate (MMTSO2). Juice from fresh garlic varied in activity between 1.76 and 2.31 microg of MMTSO2 per mg of garlic juice. The activity of juice decreased during 11 months of storage of garlic cloves at 5 degrees C from 2.31 to less than 0.1 microg of MMTSO2 per mg of juice. The broth dilution assay also used the E. coli B-103 culture, which permitted selective enumeration of this bacterium when 100 microg ml(-1) of ampicillin was incorporated into the enumerating agar. Selective enumeration was essential since the garlic juice was not sterile and, thus, contained natural flora. Growth of E. coli was unaffected by 0.1%, delayed by 0.25%, and completely inhibited at 0.5 and 2% garlic juice in broth during 24 h of incubation at 37 micro C. The minimum inhibition concentration of garlic juice by broth dilution assay was, thus, estimated to be 0.5%, which is equivalent to 3.46 microg of MMTSO2 per mg of garlic juice by the agar diffusion assay.

Bacteria↗
PubMed2000

Reduced or modified dietary fat for prevention of cardiovascular disease.

BACKGROUND: Reduction or modification of dietary fat can improve total cholesterol levels, but may also have a variety of effects, both positive and negative, on other cardiovascular risk factors. OBJECTIVES: The aim of this systematic review was to assess the effect of reduction or modification of dietary fats on total and cardiovascular mortality and cardiovascular morbidity over at least 6 months, using all available randomized clinical trials. SEARCH STRATEGY: The Cochrane Library, MEDLINE, EMBASE, CAB Abstracts, CVRCT registry and related Cochrane Groups' trial registers were searched through spring 1998, SIGLE to January 1999. Trials known to experts in the field and biographies were included through May 1999. SELECTION CRITERIA: Trials fulfilled the following criteria: 1) randomized with appropriate control group, 2) intention to reduce or modify fat or cholesterol intake (excluding exclusively omega-3 fat interventions), 3) not multi factorial, 4) healthy adult humans, 5) intervention at least six months, 6) mortality or cardiovascular morbidity data available. Inclusion decisions were duplicated, disagreement resolved by discussion or a third party. DATA COLLECTION AND ANALYSIS: Rate data were extracted by two independent reviewers and meta-analysis performed using random effects methodology. Meta-regression and funnel plots were used. MAIN RESULTS: Twenty seven studies were included (40 intervention arms, 30,901 person-years). There was no significant effect on total mortality (rate ratio 0.98, 95% CI 0.86 to 1.12), a trend towards protection form cardiovascular mortality (rate ratio 0.91, 95% CI 0. 77 to 1.07), and significant protection from cardiovascular events (rate ratio 0.84, 95% CI 0.72 to 0.99). The latter became non-significant on sensitivity analysis. Trials where participants were involved for more than 2 years showed significant reductions in the rate of cardiovascular events and a suggestion of protection from total mortality. The degree of protection from cardiovascular events appeared similar in high and low risk groups, but was statistically significant only in the former. REVIEWER'S CONCLUSIONS: The findings are suggestive of a small but potentially important reduction in cardiovascular risk in trials longer than two years. Lifestyle advice to all those at high risk of cardiovascular disease (especially where statins are unavailable or rationed), and to lower risk population groups, should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturates.

Cardiovascular Diseases↗
PubMed2000

A cross-sectional survey of the opinions on weight loss treatments of adult obese patients attending a dietetic clinic.

OBJECTIVE: To investigate the views and opinions on weight loss treatments of adult obese patients attending a dietetic clinic. DESIGN: Cross-sectional survey. SUBJECTS: 161 adults attending dietetic outpatients clinics in Portsmouth for obesity with a body mass index of at least 30 kg/m2. MEASUREMENTS: Self-administered questionnaire developed from a series of focus groups with obese adults. Key topics were previous attempts to lose weight, methods used, the role of physical activity and patients' views about treatment from health professionals. RESULTS: The preferences and usefulness of different methods to lose weight varied according to the number of attempts to lose weight, gender, age, body mass index and medical condition of the patient. Men were less likely to use special slimming products, attend slimming groups and swimming than women (odds ratios (95% confidence interval), 0.1 (0.03-0.6) for slimming groups other than Weight Watchers, 0.3 (0.1-0.80) for special slimming products and 0.3 (0.1-0.6) for swimming). Men were more likely to use physical activity (2.6 (1.1-6.2)) and in particular walking (3.7 (1.0-13.6)) and cycling (2.8 (1.0-7.6)) and were more likely to see the dietitian (3.8 (1.4-9.9)) than women. Those with more than 10 attempts to lose weight were more likely to see the dietitian (3.6(1.6-8.2)), use Weight Watchers (2.5 (1.1-5. 6)) and newspapers and magazines (4.4 (1.8-10.9)) than those with fewer attempts. The younger age group were more likely to use more vigorous forms of exercise (4.2 (1.6-11.2) for keep fit and 3.7 (1. 5-9.6) for cycling) than the older subjects. The most obese were more likely to have negative views on their treatment by health professionals (4.4 (1.9-9.8) 'chairs are never big enough' and 4.0 (1.8-8.8) 'I am regarded as a second class citizen') than those who were less obese. Those without a medical condition were more likely to exercise (2.8 (1.3-6.3)) and use books (4.8 (2.0-11.2)) than those with a medical condition. CONCLUSION: The views of obese people should be considered when planning services for the treatment of obesity and a variety of options should be available. International Journal of Obesity (2000) 24, 164-170

Adolescent↗
PubMed2000

Comparison of protein A gene sequencing with pulsed-field gel electrophoresis and epidemiologic data for molecular typing of methicillin-resistant Staphylococcus aureus.

The epidemiologic relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates is currently determined by analysis of chromosomal DNA restriction patterns by pulsed-field gel electrophoresis (PFGE). We have evaluated an alternative typing system (MicroSeq StaphTrack Kit; Perkin-Elmer Biosystems) based on the sequence analysis of the chromosomally encoded polymorphic repeat X region of the S. aureus protein A (spa) gene. A total of 69 clinical MRSA isolates were divided into 18 groups according to the number and nucleotide sequences of the spa repeats. Molecular typing results obtained both by spa sequencing and from the PFGE patterns were concordant except for one group, which contained 20 isolates recovered over a 2-year period from hospitalized patients at the Mayo Clinic. Although the spa typing patterns were indistinguishable for those isolates, PFGE analysis yielded seven related but distinguishable patterns. Further coagulase gene sequence analysis subtyped those 20 strains into four groups which followed distinct temporal and geographic distributions. During a 2-year epidemic period there were up to 7 fragment changes in PFGE patterns among epidemiologically related isolates, suggesting that PFGE may be unsuitable for long-term typing of strains involved in epidemics. Although more limited than PFGE in discriminatory power, spa sequencing analysis could be used as a screening method for typing of MRSA strains because of the shorter turnaround time, ease of use, and the inherent advantages of sequence analysis, storage, and sharing of information.

Animals↗
PubMed2000

Replication of herpes simplex virus type 1 within trigeminal ganglia is required for high frequency but not high viral genome copy number latency.

The replication properties of a thymidine kinase-negative (TK(-)) mutant of herpes simplex virus type 1 (HSV-1) were exploited to examine the relative contributions of replication at the body surface and within trigeminal ganglia (TG) on the establishment of latent infections. The replication of a TK(-) mutant, 17/tBTK(-), was reduced by approximately 12-fold on the mouse cornea compared to the rescued isolate 17/tBRTK(+), and no replication of 17/tBTK(-) in the TG of these mice was detected. About 1.8% of the TG neurons of mice infected with 17/tBTK(-) harbored the latent viral genome compared to 23% of those infected with 17/tBRTK(+). In addition, the latent sites established by the TK(-) mutant contained fewer copies of the HSV-1 genome (average, 2.3/neuron versus 28/neuron). On the snout, sustained robust replication of 17tBTK(-) in the absence of significant replication within the TG resulted in a modest increase in the number of latent sites. Importantly, these latently infected neurons displayed a wild-type latent-genome copy number profile, with some neurons containing hundreds of copies of the TK(-) mutant genome. As expected, the replication of the TK(-) mutant appeared to be blocked prior to DNA replication in most ganglionic neurons in that (i) virus replication was severely restricted in ganglia, (ii) the number of neurons expressing HSV proteins was reduced 30-fold compared to the rescued isolate, (iii) cell-to-cell spread of virus was not detected within ganglia, and (iv) the proportion of infected neurons expressing late proteins was reduced by 89% compared to the rescued strain. These results demonstrate that the viral TK gene is required for the efficient establishment of latency. This requirement appears to be primarily for efficient replication within the ganglion, which leads to a sixfold increase in the number of latent sites established. Further, latent sites with high genome copy number can be established in the absence of significant virus genome replication in neurons. This suggests that neurons can be infected by many HSV virions and still enter the latent state.

Animals↗
PubMed2000

Effects of 4 hand-drying methods for removing bacteria from washed hands: a randomized trial.

OBJECTIVE: To evaluate the effects of 4 different drying methods to remove bacteria from washed hands. SUBJECTS AND METHODS: One hundred adult volunteers participated in this randomized prospective study. All bacterial counts were determined using a modified glove-juice sampling procedure. The difference was determined between the amounts of bacteria on hands artificially contaminated with the bacterium Micrococcus luteus before washing with a nonantibacterial soap and after drying by 4 different methods (cloth towels accessed by a rotary dispenser, paper towels from a stack on the hand-washing sink, warm forced air from a mechanical hand-activated dryer, and spontaneous room air evaporation). The results were analyzed using a nonparametric analysis (the Friedman test). By this method, changes in bacterial colony-forming unit values for each drying method were ranked for each subject. RESULTS: The results for 99 subjects were evaluable. No statistically significant differences were noted in the numbers of colony-forming units for each drying method (P = .72). CONCLUSION: These data demonstrate no statistically significant differences in the efficiency of 4 different hand-drying methods for removing bacteria from washed hands.

Adult↗
PubMed1999

Novel inhibitors of glutamyl-tRNA(Glu) reductase identified through cell-based screening of the heme/chlorophyll biosynthetic pathway.

The metabolite 5-aminolevulinic acid (ALA) is an early committed intermediate in the biosynthetic pathway of heme and chlorophyll formation. In plants, 5-aminolevulinic acid is synthesized via a two-step pathway in which glutamyl-tRNA(Glu) is reduced by glutamyl-tRNA(Glu) reductase (GluTR) to glutamate 1-semialdehyde, followed by transformation to 5-aminolevulinic acid catalyzed by glutamate 1-semialdehyde aminotransferase. Using an Escherichia coli cell-based high-throughput assay to screen small molecule libraries, we identified several chemical classes that specifically inhibit heme/chlorophyll biosynthesis at this point by demonstrating that the observed cell growth inhibition is reversed by supplementing the medium with 5-aminolevulinic acid. These compounds were further tested in vitro for inhibition of the purified enzymes GluTR and glutamate 1-semialdehyde aminotransferase as confirmation of the specificity and site of action. Several promising compounds were identified from the high-throughput screen that inhibit GluTR with an I(0.5) of less than 10 microM. Our results demonstrate the efficacy of cell-based high-throughput screening for identifying inhibitors of 5-aminolevulinic acid biosynthesis, thus representing the first report of exogenous inhibitors of this enzyme.

Aldehyde Oxidoreductases↗
PubMed1999

The Health Education Authority's health and lifestyle survey 1993: who are the low fruit and vegetable consumers?

STUDY OBJECTIVE: Firstly, to determine the demographic and behavioural characteristics of low fruit and vegetable consumers. Secondly, to investigate whether knowledge and attitudes are barriers to consumption of fruit and vegetables. DESIGN: Cross sectional survey: an interviewer administrated questionnaire was used to assess the demographic, knowledge, attitude, and behavioural characteristics of the respondents. SETTING: England. PARTICIPANTS: Random sample of 5553 men and women aged between 16 and 74 years. Response rate 70%. MAIN RESULTS: The main demographic characteristics of the respondents identified as low consumers of fruit and vegetables (less than daily consumption of either fruit or vegetables) were age, sex, and smoking status. The adjusted odds ratios were 2.59 for those aged 16-24 years compared with those aged 45-74 years, 2.17 for men compared with women, and 1.77 for current smokers compared with never smokers. The most important knowledge and attitude statements after adjusting for the demographic variables were disagreeing with the statement "healthy foods are enjoyable" (odds ratio 1.90) and agreeing with the statement "I don't really care what I eat" (odds ratio 1.76). The impact of knowledge seemed less important than attitudes about a healthy diet in characterising a low fruit and vegetable consumer. CONCLUSIONS: These findings are relevant to future strategies for improving intake of fruit and vegetables, but demonstrate the complexity of interventions required, and the dangers inherent in assuming simplistic relations between psychosocial factors and behaviour.

Adolescent↗
PubMed1998

Factors which influence 'healthy' eating patterns: results from the 1993 Health Education Authority health and lifestyle survey in England.

OBJECTIVES: This study explores the factors that influence eating patterns in a nationally representative sample of the English population. DESIGN: Subjects were interviewed in 1993; questions covered basic demographic details, attitudes about nutrition, and they completed a short food frequency questionnaire that had previously been validated. Cluster analysis was used to summarize dietary intake into more or less healthy clusters. SETTING: A random sample of the English population. SUBJECTS: A cross-sectional survey of 5553 men and women (response rate 70%) aged between 16 and 74 years. RESULTS: As defined from the cluster analysis about half the sample were currently reporting a more healthy diet; respondents in the better educated middle-aged demographic cluster were more likely to report eating a more healthy diet than respondents in the younger lower-income family cluster. About three-quarters of all respondents believed that they either already ate a healthy diet or had changed to a healthy diet in the last 3 years. For those respondents who said they were eating a healthy diet about half of them were eating a more healthy diet. Respondents who had not changed their diet were more likely than those who had to believe that healthy foods were just another fashion (men 34% v. 13%; women 30% v. 12%), or expensive (men 50% v. 35%; women 53% v. 40%); they were less likely to care about what they ate (men 45% v. 13%; women 27% v. 7%). Nearly three-quarters of all respondents agreed that experts never agree about what foods are good for you. Younger, low-income families, and those who smoked, were the group least likely to be eating a more healthy diet. CONCLUSIONS: The results of this study suggest that about half of the population has reported a change to a healthier diet over the last 3 years and that overall about half of the population report eating a healthy diet. Those who had not made any change and were currently reporting a less healthy diet were more likely to smoke and come from the 'worse off group in the survey; they were also more likely to hold negative attitudes about healthy eating. A more focused and integrated approach to promoting healthy lifestyle in general is required, while at the same time ensuring that there is continued support for the majority of the population who have made healthy dietary changes.

Adolescent↗
PubMed1998

Molecular, serological, and clinical features of 16 consecutive cases of invasive streptococcal disease. Southeastern Minnesota Streptococcal Working Group.

We performed a comprehensive analysis of the molecular, serological, and clinical features of 16 consecutive cases of invasive streptococcal disease (ISD). The majority of cases were linked to two group A streptococcus (GAS) clones closely related by pulsed-field gel electrophoresis (PFGE) and designated as PFGE-1 and PFGE-1.1. These clones, serotyped as M-3, T-3/B3264, carried an allelic variant of the gene that encodes pyrogenic exotoxin A (speA3) and the gene that encodes streptococcal superantigen (SSA) but different emm alleles that encode M-protein. The characteristics and clinical features of patients were similar to those described in previous reports, regardless of the responsible GAS clone. However, worse clinical outcomes (shock and death) were more frequent when patients infected with PFGE1/1.1 clones were considered as a group and compared with all other patients as a group. One striking feature in some patients with deep tissue infection was a lack of inflammatory cells despite the presence of numerous streptococci. An evaluation of PFGE profiles of GAS isolated elsewhere demonstrated that the PFGE-1 clone has caused invasive disease in other locations in the United States and in Japan.

Adult↗
PubMed1998

The latent herpes simplex virus type 1 genome copy number in individual neurons is virus strain specific and correlates with reactivation.

The viral genetic elements that determine the in vivo reactivation efficiencies of fully replication competent wild-type herpes simplex virus (HSV) strains have not been identified. Among the common laboratory strains, KOS reactivates in vivo at a lower efficiency than either strain 17syn+ or strain McKrae. An important first step in understanding the molecular basis for this observation is to distinguish between viral genetic factors that regulate the establishment of latency from those that directly regulate reactivation. Reported here are experiments performed to determine whether the reduced reactivation of KOS was associated with a reduced ability to establish or maintain latent infections. For comparative purposes, latent infections were quantified by (i) quantitative PCR on DNA extracted from whole ganglia, (ii) the number of latency-associated transcript (LAT) promoter-positive neurons, using KOS and 17syn+ LAT promoter-beta-galactosidase reporter mutants, and (iii) contextual analysis of DNA. Mice latently infected with 17syn+-based strains contained more HSV type 1 (HSV-1) DNA in their ganglia than those infected with KOS strains, but this difference was not statistically significant. The number of latently infected neurons also did not differ significantly between ganglia latently infected with either the low- or high-reactivator strains. In addition to the number of latent sites, the number of viral genome copies within the individual latently infected neurons has recently been demonstrated to be variable. Interestingly, neurons latently infected with KOS contained significantly fewer viral genome copies than those infected with either 17syn+ or McKrae. Thus, the HSV-1 genome copy number profile is viral strain specific and positively correlates with the ability to reactivate in vivo. This is the first demonstration that the number of HSV genome copies within individual latently infected neurons is regulated by viral genetic factors. These findings suggest that the latent genome copy number may be an important parameter for subsequent induced reactivation in vivo.

3T3 Cells↗
PubMed1998

General principles of antimicrobial therapy.

Antimicrobial agents are appropriate treatment for acute, severe, persistent, or progressive infectious diseases. The efficacy of treatment depends on the accuracy of the diagnosis of infection and the appropriateness of the antimicrobial agent for the causative microorganism. In this symposium, the antimicrobial agents reviewed correspond with the bacterial, fungal, viral, mycobacterial, parasitic, chlamydial, and other microorganisms that cause disease in humans. Usually, the etiologic possibilities can be limited on the basis of the history and physical examination, laboratory tests, or results of treatment trials. Many of the same findings, however, can result from noninfectious, other inflammatory, or unknown mechanisms. Manifestations such as fever and organ dysfunction are nonspecific and often not caused by an infectious process. Even when infection is clinically apparent, the causative microorganism may not be identified, and empiric treatment with broad-spectrum agents is appropriate in many cases of serious disease.

Ambulatory Care↗
PubMed1997

An outbreak of invasive group A streptococcal disease associated with high carriage rates of the invasive clone among school-aged children.

OBJECTIVES: To determine if a common strain of group A streptococcus was responsible for an outbreak of invasive streptococcal disease in southeastern Minnesota and to determine whether this strain was prevalent among residents of this area during the outbreak who either had streptococcal pharyngitis or were asymptomatic streptococcal carriers. DESIGN: Pharyngeal culture survey and case-contact evaluation. SETTING: Three adjacent counties in southeastern Minnesota defined as the outbreak area. Outbreak period, January 1 through March 31, 1995. PATIENTS: Seven patients with invasive streptococcal infection, 1249 patients (adults and children) with sore throat who resided in the outbreak area, children from an elementary school located in 1 community where the majority of invasive cases occurred, and 896 students from 3 schools located in Minnesota counties outside the outbreak area. MEASUREMENTS: Pulsed-field gel electrophoresis (DNA fingerprinting) of group A streptococcal isolates obtained from patients with invasive disease, throat swabs of patients with sore throat, and throat swabs of asymptomatic school-aged children. RESULTS: All patients with outbreak-associated invasive disease had group A streptococcal isolates that were indistinguishable by pulsed-field gel electrophoresis. Additional testing showed that these isolates carried significant virulence factors including pyrogenic exotoxin A and streptococcal superantigen. Five of these 7 patients with invasive disease had underlying medical conditions; 4 developed toxic shock syndrome and died (case fatality, 57%). The outbreak-associated group A streptococcal clone was found in 69 (26.5%) of the 260 patients with sore throat from whom group A streptococcus was isolated. The frequency of the outbreak clone among pharyngeal carriers from the 3 schools outside the outbreak area was significantly less (range, 0%-10%) than in children from the school in the outbreak area (78%; relative risk, 29; 95% confidence interval, 11.1-78.1; P<.001). Four of the 7 patients with outbreak-associated disease had contact with children who attended the school in the outbreak area. CONCLUSIONS: A single clone of group A streptococcus was responsible for 7 cases of invasive streptococcal disease during an outbreak in Minnesota and for a significant number of pharyngitis cases that also occurred during the outbreak. Invasive disease occurred most frequently in persons with underlying medical conditions. This outbreak was also associated with increased carriage rates of the invasive streptococcal clone among community school-aged children. Cases of invasive group A streptococcal infection may therefore reflect the tip of the iceberg with regard to the burden of colonization of a specific invasive streptococcal clone in a community.

Adult↗
PubMed1997

The herpes simplex virus type 1 latency-associated transcript gene regulates the establishment of latency.

Herpes simplex virus type 1 establishes latent infections in sensory neurons. During latency only one locus, the latency-associated transcript (LAT), is abundantly transcribed. Several lines of evidence suggest that this locus is required for the efficient reactivation from latency in experimental models. However, it is not yet clear whether this is a direct effect on the reactivation process per se or, as we have suggested, an indirect effect resulting from a decreased efficiency of establishment of latent infections. In this report wild-type and genetically engineered viral mutants were analyzed in a mouse model using a recently developed approach to precisely quantify latently infected neurons. It was found that strain KOS/M established latent infections, as defined by the presence of the viral genome, in about 30% of the neurons. Thirty-three percent of the mice with this latent viral burden reactivated in vivo following hyperthermic stress. In contrast, mutants in which either the basal LAT promoter or the 5' end of the LAT gene was deleted established latency in only 10% of trigeminal neurons (P < 0.00001), and these mice were impaired for reactivation. Repair of the locus resulted in wild-type levels of establishment and reactivation, mapping this function to the LAT region. Finer mapping demonstrated that a 2.3-kb fragment that contains the major LAT transcripts was sufficient to promote efficient establishment and subsequent reactivation when expressed in the context of a foreign gene. Hyperthermic stress applied during the first 3 days postinfection resulted in greatly increased numbers of neurons harboring the latent viral genome. This approach was found to increase the level of establishment of LAT-null mutants to that normally achieved by wild-type KOS/M. These establishment-repaired mice reactivated with wild-type efficiency. Thus, the LAT gene serves to increase the number of neurons in which latency is established, and no direct role for the LAT locus in reactivation could be demonstrated.

Animals↗
PubMed1996

A novel 'piggyback' packaging system for herpes simplex virus amplicon vectors.

Recombinant and amplicon vectors derived from herpes simplex virus type 1 (HSV-1) have proven to be an efficient means of gene delivery to cells in culture and in vivo. In this study, a system was developed to make propagation of the amplicon vector and helper virus mutually dependent on each other, in a "piggyback' fashion. This combined system supports maintenance and enrichment of the amplicon vector when propagating stocks, while allowing the helper virus to serve as a recombinant vector in its own right. Amplicons bearing a gene essential for HSV-1 replication, IE3, as well as the Escherichia coli lacZ marker gene, were propagated using a mutant virus (d120) deleted in the same essential gene. Vector stocks could be propagated in Vero cells and other cultured cells not transfected with the IE3 gene with markedly delayed cytopathic effects, as compared to wild-type virus. Relatively high titers of amplicon vectors (6 x 10(7) infectious units/ml) were achieved with this piggyback system in Vero cells, with an apparent ratio of amplicon vector: helper virus of up of 5:1 under some conditions; however, recombinant wild-type virus was also generated. Injection of these stocks into experimental gliomas in rodent brain revealed gene delivery to tumor cells mediated by both amplicon vectors (lacZ) and helper virus (HSV-thymidine kinase), with no apparent neuropathology of normal brain. This basic piggyback vector model is amenable to modifications to promote conditional propagation of vectors in vivo and to allow incorporation of multiple transgene elements into both the amplicon and recombinant helper virus vectors.

Animals↗