113 Where Did the Ureteric Stent Disappear? – Mystery Solved

38-year-old male presented to A&E with bilateral flank and suprapubic pain associated with mild VH. A CTKUB was suggestive of 10 cm ureteric stent noted in the left distal ureter and a few left sided lower calyceal non-obstructive stones.

Patient denied any previous urological procedures or significant history. He even called up his mother in Hungary to ensure that. He was discharged with an outpatient follow up after his symptoms settled. In the clinic it was decided to carry out a CT Urogram and a flexible cystoscopy. The urine was also sent for cytology and acid-fast bacilli. His Calcium and urate profile was normal.

On a CT Urogram, mysteriously the 10cm distal stent like calcification and the lower calyceal stones were not found, and on flexible cystoscopy the bladder looked pristine. The patient’s symptoms had resolved, and he had not spotted passage of any stone as he was asked to stay vigilant.

Discussion

Flexible cystoscopy along with CT Urogram was likely the best approach in this case- as it provided a holistic approach and excluded any upper tract pathology as well as a FB or abnormality in the urinary bladder.

114 Urology Stent Recall Registry

Aim

To analyse how many stent procedures were recorded (on the stent registry tool in CERNER introduced at our busy DGH) for patients undergoing an insertion of ureteric stent, this ensures patient safety is not compromised by making sure stent(s) are removed or replaced at the right time.

Method

Retrospective Collection of data for 3 months. Which was followed by intervention, and a further collection of data for 3 months after implementation of changes. Parameters collected included age, gender, stent recall registered, comments present in registry, removal date.

Results

In the first loop only 32.6% of the patient had the stent recall registered on the directory. Post Intervention (IT training, Posters, presenting half audit at clinical governance) the registry rate was 59%. The most common reason for insertion was for stone, followed by longstanding hydronephrosis. It was also interesting to note that 2 patients were found who were lost in follow up and an urgent action was taken to review them.

Conclusions

Cerner, which is popular in NHS trusts across UK has the feasibility of having an online stent register where the information recorded gets transferred straight to the Urology office, hence ensuring correct time of removal/ exchange of stents. Trusts across UK can develop this online registration scheme in their IT system. Developing the online registry system and encouraging this audit in all NHS trusts will significantly impact the welfare and safety of patients and reduce the economic burden of NHS in dealing with complications associated with stents.

POS0701 ANIFROLUMAB, AN ANTI-INTERFERON-Α RECEPTOR MONOCLONAL ANTIBODY IN SYSTEMIC LUPUS ERYTHEMATOSUS- A META ANALYSIS

Background:

Type I interferons such as Anifrolumab have been implicated in Systemic lupus erythematosus (SLE) pathogenesis on the basis of increased interferon-stimulated gene expression and genetic susceptibility. Little is known regarding its efficacy and safety profile.

Objectives:

To assess the efficacy and safety of Anifrolumab in patients with SLE.

Methods:

Electronic databases (PubMed, Embase, Scopus, Cochrane) were searched from inception until December 15th, 2020. Unadjusted odds ratios (OR) were calculated from dichotomous data using Mantel Haenszel (M-H) random-effects with statistical significance to be considered if the confidence interval excludes 1 and p<0.05. The primary outcome of interest was British Isles Lupus Assessment Group (BILAG)-based Composite Lupus Assessment (BICLA). Secondary outcomes included the proportion of patients who achieved an SLE responder index of 4 (SRI-4) reduction of 50% or more in the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI), reductions in the glucocorticoid dose and adverse effects.

Results:

A total of three studies1,2,3 with 839 participants (Anifrolumab=372, Placebo=467) were included in our analysis. Follow-up duration was at week 52. A statistically significant different was observed in the Anifrolumab arm in terms of BICLA response (OR 0.44 95%CI 0.34-0.59;p < 0.00001, I2=4), ≥50% reduction in CLASI activity score (OR 0.36 95%CI 0.21-0.60;p=0.0001, I2=0), glucocorticoid reduction (OR 0.41 95%CI 0.28-0.59;p<0.00001; I2=0) and SRI-4 response (OR 0.52 95% CI 0.30-0.90; p=0.02, I2=75). However, Adverse events were less likely in the placebo arm as compared to Anifrolumab (OR 1.54 95%CI 1.05-2.25; p=0.03; I2=0).

Conclusion:

Anifrolumab was found to be more effective than placebo for the management of SLE, but may also cause more severe adverse effects.

References:

[1]Morand EF, Furie R, Tanaka Y, Bruce IN, Askanase AD, Richez C, Bae SC, Brohawn PZ, Pineda L, Berglind A, Tummala R; TULIP-2 Trial Investigators. Trial of Anifrolumab in Active Systemic Lupus Erythematosus. N Engl J Med. 2020 Jan 16;382(3):211-221. doi: 10.1056/NEJMoa1912196. Epub 2019 Dec 18. PMID: 31851795.

[2]Furie R, Khamashta M, Merrill JT, Werth VP, Kalunian K, Brohawn P, Illei GG, Drappa J, Wang L, Yoo S; CD1013 Study Investigators. Anifrolumab, an Anti-Interferon-α Receptor Monoclonal Antibody, in Moderate-to-Severe Systemic Lupus Erythematosus. Arthritis Rheumatol. 2017 Feb;69(2):376-386. doi: 10.1002/art.39962. PMID: 28130918; PMCID: PMC5299497.

[3]Furie RA, Morand EF, Bruce IN, et al. Type I interferon inhibitor anifrolumab in active systemic lupus erythematosus (TULIP-1): a randomised, controlled, phase 3 trial. Lancet Rheumatol 2019; 1(4):e208-e219.

Disclosure of Interests:

None declared

Association of Thyroid Function Test Abnormalities and Thyroid Autoimmunity With Preterm Birth: A Systematic Review and Meta-analysis

Importance

Maternal hypothyroidism and hyperthyroidism are risk factors for preterm birth. Milder thyroid function test abnormalities and thyroid autoimmunity are more prevalent, but it remains controversial if these are associated with preterm birth.

Objective

To study if maternal thyroid function test abnormalities and thyroid autoimmunity are risk factors for preterm birth.

Data Sources and Study Selection

Studies were identified through a search of the Ovid MEDLINE, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, and Google Scholar databases from inception to March 18, 2018, and by publishing open invitations in relevant journals. Data sets from published and unpublished prospective cohort studies with data on thyroid function tests (thyrotropin [often referred to as thyroid-stimulating hormone or TSH] and free thyroxine [FT4] concentrations) or thyroid peroxidase (TPO) antibody measurements and gestational age at birth were screened for eligibility by 2 independent reviewers. Studies in which participants received treatment based on abnormal thyroid function tests were excluded.

Data Extraction and Synthesis

The primary authors provided individual participant data that were analyzed using mixed-effects models.

Main Outcomes and Measures

The primary outcome was preterm birth (<37 weeks' gestational age).

Results

From 2526 published reports, 35 cohorts were invited to participate. After the addition of 5 unpublished data sets, a total of 19 cohorts were included. The study population included 47 045 pregnant women (mean age, 29 years; median gestational age at blood sampling, 12.9 weeks), of whom 1234 (3.1%) had subclinical hypothyroidism (increased thyrotropin concentration with normal FT4 concentration), 904 (2.2%) had isolated hypothyroxinemia (decreased FT4 concentration with normal thyrotropin concentration), and 3043 (7.5%) were TPO antibody positive; 2357 (5.0%) had a preterm birth. The risk of preterm birth was higher for women with subclinical hypothyroidism than euthyroid women (6.1% vs 5.0%, respectively; absolute risk difference, 1.4% [95% CI, 0%-3.2%]; odds ratio [OR], 1.29 [95% CI, 1.01-1.64]). Among women with isolated hypothyroxinemia, the risk of preterm birth was 7.1% vs 5.0% in euthyroid women (absolute risk difference, 2.3% [95% CI, 0.6%-4.5%]; OR, 1.46 [95% CI, 1.12-1.90]). In continuous analyses, each 1-SD higher maternal thyrotropin concentration was associated with a higher risk of preterm birth (absolute risk difference, 0.2% [95% CI, 0%-0.4%] per 1 SD; OR, 1.04 [95% CI, 1.00-1.09] per 1 SD). Thyroid peroxidase antibody-positive women had a higher risk of preterm birth vs TPO antibody-negative women (6.6% vs 4.9%, respectively; absolute risk difference, 1.6% [95% CI, 0.7%-2.8%]; OR, 1.33 [95% CI, 1.15-1.56]).

Conclusions and Relevance

Among pregnant women without overt thyroid disease, subclinical hypothyroidism, isolated hypothyroxinemia, and TPO antibody positivity were significantly associated with higher risk of preterm birth. These results provide insights toward optimizing clinical decision-making strategies that should consider the potential harms and benefits of screening programs and levothyroxine treatment during pregnancy.

Antibiotic susceptibility in Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes in Pakistan: a review of results from the Survey of Antibiotic Resistance (SOAR) 2002-15

OBJECTIVES

To investigate changes in the antibiotic susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes from the Survey of Antibiotic Resistance (SOAR) in community-acquired respiratory tract infections (CA-RTIs) between 2002 and 2015 in Pakistan.

METHODS

This is a review based on previously published studies from 2002-03, 2004-06 and 2007-09 and also new data from 2014-15. Susceptibility was determined by Etest(®) or disc diffusion according to CLSI and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 706 isolates from CA-RTIs comprising 381 S. pneumoniae, 230 H. influenzae and 95 S. pyogenes were collected between 2002 and 2015 and tested against a range of antibiotics. Antibiotic resistance in S. pneumoniae rose steeply from 2002 to 2009, with isolates non-susceptible to penicillin and macrolides increasing from 10% to 34.1% and from 13%-14% to 29.7%, respectively. Susceptibility to amoxicillin/clavulanic acid (and by inference amoxicillin) remained between 99.4% and 100% from 2002 to 2015. Over the years, the prevalence of susceptibility to cefuroxime was 98%-100% among S. pneumoniae. Resistance in S. pneumoniae to some older antibiotics between 2007 and 2009 was high (86.8% for trimethoprim/sulfamethoxazole and 57.2% for tetracycline). Between 2002 and 2015, ampicillin resistance (β-lactamase-positive strains) among H. influenzae has remained low (between 2.6% and 3.2%) and almost unchanged over the years (H. influenzae was not tested during 2004-06). For S. pyogenes isolates, macrolide resistance reached 22%; however, susceptibility to penicillin, amoxicillin/clavulanic acid and cefuroxime remained stable at 100%.

CONCLUSIONS

In S. pneumoniae from Pakistan, there has been a clear reduction in susceptibility to key antibiotics since 2002, but not to amoxicillin/clavulanic acid (amoxicillin) or cefuroxime. However, susceptibility in H. influenzae has remained stable. Local antibiotic susceptibility/resistance data are essential to support informed prescribing for CA-RTIs and other infections.

A survey of reporting of colorectal cancer in Scotland: compliance with guidelines and effect of proforma reporting

AIMS

The main purpose of the study was to present a baseline audit of reporting of colorectal cancers resection specimens in Scotland, audited against the Royal College of Pathologists (RCPath) standards (2007) and NHS Quality Improvement Scotland (NHS QIS) standards.

METHODS

50 consecutive rectal and 50 consecutive colonic cancer cases from 2011 were audited from 10 Scottish health boards involved in colorectal cancer reporting (n=953). The rates of reporting of serosal involvement, extramural venous invasion (EMVI) and the mean numbers of lymph nodes found were audited against RCPath standards and compared between units that routinely used a reporting proforma versus those that did not.

RESULTS

The performance in reporting of rectal cancer was generally worse than for colonic cancer, with only three units meeting the RCPath standards for reporting of rectal cancer. There were significant differences between units that routinely used a proforma, with the non-proforma group failing to meet the minimum standards for both serosal involvement (6%) and EMVI (24%). In the non-proforma group, 56% of rectal cases had a mean lymph node count of 12 or more compared with 81% in the proforma group.

CONCLUSIONS

Significant differences exist in the frequencies with which important adverse prognostic features are reported by pathologists across 10 Scottish health boards. This has potential implications for patient care. Health boards that make routine use of reporting proformas are more likely to meet RCPath guidelines for reporting of these important pathological parameters.

Evaluation of the pressure leak test in increasing the lifespan of flexible ureteroscopes

INTRODUCTION

Flexible ureteroscopes are expensive and delicate instruments that are integral in the offering of a minimally invasive technique of diagnosis and treatment of urolithiasis. Published literature has identified the importance of early damage recognition in preventing frequent use of the scope that would lead to further damage and high repair and replacement costs. Our study was designed to examine the outcome of the pressure leak test on the condition of flexible ureteroscopes after every use and analysing the damage and costs of maintenance.

PATIENTS AND METHODS

A prospective study was designed with two treatment groups. Group 1, 95 consecutive procedures (n = 95) of flexible ureterorenoscopy and laser fragmentation of renal calculi were performed with ACMI DUR 8, (a scope with no in-built leak test facility). This was compared against group 2, where 98 procedures of laser fragmentation of renal calculi (n = 98) were performed using Storz Flex X(2) Ureteroscopes (with a in-built leak test facility). All scopes in Group 2 were tested for pressure leak after every procedure and the outcome of the tests recorded.

RESULTS

Both groups were comparable for grade of surgeon; stone location, size & number; access sheath usage and duration of lasering. In Group 1, there were seven scope damages resulting in repairs/replacement amounting to costs $46264.40 (7.1% damage). In Group 2, three scopes revealed a positive pressure leak test, implying damage with repair costs of $9952.80 (3.1% damage) (p < 0.05). Significant cost savings and reduction in downtime were made in Group 2.

CONCLUSIONS

Pressure leak testing following flexible ureterorenoscopy helped to significantly control costs of maintenance and repair. Newer scopes should have a leak testing mechanism as it prevents further detrimental damage to the scope, build-up of repair costs are avoided and there is an increase in the longevity of these delicate instruments.

Challenging boundaries: an enhanced recovery programme for radical cystectomy

INTRODUCTION

The implementation of enhanced recovery programmes (ERPs) in colorectal surgery has seen improvements in the length of inpatient stay with no increase in complications. We investigated the role of ERP in radical cystectomy at our institution.

METHODS

Prospective data were collected from 26 consecutive patients prior to the introduction of the ERP and 51 patients who underwent open radical cystectomy within an ERP. Individuals in the ERP cohort did not receive bowel preparation or nasogastric drainage but received preoperative carbohydrate drinks, perioperative epidural analgesia and immediate mobilisation on day 1. Primary outcome measures included duration of intensive care unit (ICU) stay and length of hospital stay. Secondary outcome measures included the time to the passage of flatus and faeces, and time to mobilisation. Other measures that were analysed included operation time and complications.

RESULTS

Baseline characteristics for both groups were similar. The median length of hospital stay fell from 11.5 days to 10.4 days and the mean ICU stay dropped from 2.4 days to 1.0 days (p=0.01). Time to removal of nasogastric tube, and time to passage of flatus and faeces were significantly shorter in the ERP group, as was the time to full oral diet. Clavien complication rates and 30-day mortality rates were similar in both groups. There were no readmissions.

CONCLUSIONS

ERP in radical cystectomy is safe and not associated with any increase in complications or readmissions. It is associated with reductions in ICU stay, and could also reduce length of hospital stay and duration of postoperative ileus.

Comparison of seasonal phenol and p-cresol emissions from ground-level area sources in a dairy operation in central Texas

Although there are more than 200 odor-causing volatile organic compounds (VOCs), phenol and p-cresol are two prominent odor-causing VOCs found downwind from concentrated animal feeding operations (CAFOs). The VOC emissions from cattle and dairy production are difficult to quantify accurately because of their low concentrations, spatial variability, and limitations of available instruments. To quantify VOCs, a protocol following US. Environmental Protection Agency (EPA) Method TO-14A has been established based on the isolation flux chamber method and a portable gas chromatograph (GC) coupled with a purge-and-trap system. The general objective of this research was to quantify phenol and p-cresol emission rates (ERs) from different ground-level area sources (GLASs) in a free-stall dairy during summer and winter seasons using this protocol. Two-week-long sampling campaigns were conducted in a dairy operation in central Texas. Twenty-nine air samples were collected during winter and 37 samples were collected during summer from six specifically delineated GLASs (barn, loafing pen, lagoon, settling basin, silage pile, and walkway) at the free-stall dairy. Thirteen VOCs were identified during the sampling period and the GC was calibrated for phenol and p-cresol, the primary odorous VOCs identified. The overall calculated ERs for phenol and p-cresol were 2656 +/- 728 and 763 +/- 212 mg hd(-1) day(-1), respectively, during winter. Overall phenol and p-cresol ERs were calculated to be 1183 +/- 361 and 551 +/- 214 mg hd(-1) day(-1), respectively, during summer. In general, overall phenol and p-cresol ERs during winter were about 2.3 and 1.4 times, respectively, higher than those during summer.

Germ cell tumour: late recurrence after 43 years

We report the late relapse of a patient following 43 years of surveillance of a germ cell tumour, thought to be a pure seminoma, having undergone yolk sac differentiation. The longest previous recorded time to relapse was 32 years (malignant teratoma with adenocarcinoma de-differentiation).(1) This case report demonstrates a late relapse of a testicular germ cell tumour is possible whatever the initial stage. European Association of Urology guidelines state close and active follow-up is mandatory for at least five years' surveillance due to the high and often late rate of relapse. Furthermore, they also suggest continuing follow-up although it is unclear as to how long this should last.(7)

Wnt and SHH in prostate cancer: trouble mongers occupy the TRAIL towards apoptosis

Prostate cancer is a serious molecular disorder that arises because of reduction in tumour suppressors and overexpression of oncogenes. The malignant cells survive within the context of a three-dimensional microenvironment in which they are exposed to mechanical and physical cues. These signals are, nonetheless, deregulated through perturbations to mechanotransduction, from the nanoscale level to the tissue level. Increasingly sophisticated interpretations have uncovered significant contributions of signal transduction cascades in governing prostate cancer progression. To dismantle the major determinants that lie beneath disruption of spatiotemporal patterns of activity, crosstalk between various signalling cascades and their opposing and promoting effects on TRAIL-mediated activities cannot be ruled out. It is important to focus on that molecular multiplicity of cancer cells, various phenotypes reflecting expression of a variety of target oncogenes, reversible to irreversible, exclusive, overlapping or linked, coexist and compete with each other. Comprehensive investigations into TRAIL-mediated mitochondrial dynamics will remain a worthwhile area for underlining causes of tumourigenesis and for unravelling interference options.

Acidic and alkaline bottom ash and composted manure blends as a soil amendment

Potential water quality impacts associated with using bottom ash (BA) and composted dairy manure (CM) as a soil amendment were evaluated in this study. Two column studies were conducted to evaluate three blends of acidic BA and CM (BA:CM, v/v) namely, B1ac (95:5), B2ac (90:10), and B3ac (80:20) and three blends of alkaline BA and CM (BA:CM, v/v), namely, B1al (95:5), B2al (90:10), and B3al (80:20) under constant head water table conditions. Samples from standing water (top) and leachate (bottom) were collected at weekly intervals until day 49 to evaluate the effects of different blend ratios and elapsed time on standing water and leachate chemical and physical properties. A higher CM content in both acidic and alkaline blends resulted in higher leachate concentrations for solids and nutrients tested in this study. Alkaline blends had higher standing water and leachate nutrients concentration compared to acidic blends. After day 28, standing water total dissolved solids (TDS) concentrations for all acidic blends was below the USEPA drinking water standard however, TDS value for alkaline blend was always below the standard. Similar trends were also observed for NO3-N and phosphorus (P) concentrations for both blends. Based on these findings, it was concluded that acidic and alkaline blends B1ac, B1al, B2ac and B2al may be considered as a soil amendment material.

Impact of dairy housing practices on lagoon effluent characteristics: implications for nitrogen dynamics and salt accumulation

Increasing emphasis on maintaining environmental integrity by dairy operations warrants examination of management influence on waste characteristics. Complete profiles of anaerobic dairy lagoons for eleven operations in central Texas, distinguished by use of dry-lot and hybrid (i.e., facilities comprised of free stalls with smaller dry-lot areas) management systems, were analyzed for 15 physicochemical parameters. Although solids, pH and TKN values were similar between housing type, statistical differences in NH4-N, P, K, Mg, Na, Mn, Cu and electrical conductivity (EC) were observed. The discrepancies were attributed to dissimilar cattle activity, where cows spend more time near flush alleys in hybrid systems than dry-lot systems, which facilitates waste transport to anaerobic lagoons. These results suggest a possible difference in N dynamics between lagoon types, which in turn would have implications for NH3 volatilization. Potential salt-stress impact on both lagoon effectiveness and pastures receiving land-applied lagoon effluent may also be enhanced by hybrid systems. This study not only contributes data on anaerobic lagoon characteristics, but also provides additional considerations for dairy producers striving to meet more rigorous regulations while attempting to protect soil resources for crop production.

Evaluation of bottom ash and composted manure blends as a soil amendment material

The long-term goal of this project was to find alternative uses for bottom ash (BA) and composted dairy manure (CM), by-products of coal combustion and livestock production, respectively. The study discussed in this paper focused on potential water quality impacts associated with using blended BA and CM as a soil amendment. The constituents of BA and CM include heavy metals and other chemicals that, while essential nutrients for plant growth, also pose a potential threat to water quality. Four blends (BA:CM, v/v) namely, B1 (100%:0%), B2 (70%:30%), B3 (50%:50%) and B4 (0%:100%), were subjected to flow-through water table management and two blends, B2 (70%:30%) and B3 (50%:50%), were subjected to constant head water table management using de-ionized water. Leachate and standing water from saturated and flooded blends of BA and CM were examined for total solids (TS), volatile solids (VS), COD, pH, total Kjeldahl nitrogen (TKN), NO(3)-N, total P, total K as well as selected metals over a 5 and 7 week period for flow-through and constant head watertables, respectively. The results showed that higher CM content resulted in higher TS, VS, TKN, P and K concentrations in the leachate and standing water. Concentrations of these constituents were higher in leachate than in the standing water. Even though, marked reductions of most chemicals in the leachate and standing water were realized within one to three weeks, initially high concentrations of chemicals in leachate and standing water from these particular blends made them unsuitable as soil amendment material. Based upon these results, it was concluded that additional column studies of BA and CM blends with reduced CM content (5%, 10% and 20%) should be performed to further assess the feasibility of BA and CM blends as an environmentally safe soil amendment material.

Widespread Occurrence of Cotton leaf curl virus on Radish in Pakistan

The current epidemic of cotton leaf curl disease (CLCuD) in Pakistan started in 1988 with the natural host range limited to a few plant species in the family Malvaceae. However, we have observed expansion in the host range of the virus, and several non-Malvaceous plants were found to be infected with the virus. Characteristic symptoms of CLCuD such as leaf curl and enations have been observed on radish plants, primarily in kitchen gardens. However, in 1999, levels of infection of 10 to 90% were observed both in commercial fields and kitchen gardens in the Punjab province of Pakistan. Both symptomatic and nonsymptomatic samples were collected from five different locations. Total DNA was isolated, dot-blotted on nylon membrane, and a full-length clone corresponding to DNA A of cotton leaf curl virus was labeled with ³²P dCTP and used as a probe for the detection of a begomovirus. Strong signals were observed in symptomatic plants while no signals were observed in nonsymptomatic plants. Infection with a begomovirus was further confirmed by polymerase chain reaction (PCR) using degenerate primers for DNA A (1). Primers specific for the two distinct begomoviruses associated with CLCuD were also used in PCR reactions (2), and products of the expected size were obtained from all symptomatic samples, confirming infection with begomoviruses similar to those associated with CLCuD. A full-length probe of a nanovirus-like molecule associated with cotton leaf disease (3), called DNA 1 was labeled with ³²P dCTP and detected the virus only in symptomatic plants. Similarly, primers specific for DNA 1 (3) amplified a product of expected size when used in PCR. On the basis of symptomatology and the detection of specific viral components associated with the disease, we confirmed that radish plants are infected with Cotton leaf curl virus (CLCuV). Since radish is a short duration crop, infection of CLCuV in radish may not serve as a direct source of infection for the next cotton crop. However, it is a potential threat to tomato crops which overlap with radish in the Punjab province. The detection of CLCuD in radish is another example of the mobilization of begomoviruses to previously unknown hosts. References: (1) M. R. Rojas et al. Plant Dis. 77:340, 1993. (2) S. Mansoor et al. Pak. J. Bot. 31:115, 1999. (3) Mansoor et al. Virology 259:190, 1999.