Feasibility study to develop a common in vitro D antigen assay for inactivated poliomyelitis vaccines

A feasibility study was organised to determine the possibilities for development of a common in vitro assay for determination of D-antigen content in inactivated poliomyelitis vaccines (IPV). 3 different methods were tested on a selection of non-combined IPV vaccines from the European market. The results of this preliminary study suggest that for vaccines with a similar strain composition similar results would be achieved regardless of which of the three methods was used. Nevertheless, for one vaccine with a slightly different strain composition the results obtained depended on which method was applied. This highlights the need to take into account the strain composition in any future development of a common method. The study also highlighted the importance of standardising the statistical approach to analysis of results, since one laboratory obtained different sets of results by applying different statistical analysis to the same raw data. While no immediate need was seen for a large collaborative study to establish a common method, participants encouraged the idea of further study, in particular with respect to the different strain compositions. Adaptation of a common method will also require further analysis of the needs for combined vaccines, including the steps and conditions for de-sorption.

Validation study to evaluate the reproducibility of a candidate in vitro potency assay of newcastle disease vaccines and to establish the suitability of a candidate biological reference preparation

A quantification assay for the Haemagglutinin-Neuraminidase (HN) protein of Newcastle Disease Virus (NDV) has been developed at CIDC-Lelystad as a candidate in vitro potency test for inactivated Newcastle disease (ND) vaccines. In studies performed at CIDC-Lelystad, a high correlation was demonstrated between the results of this candidate in vitro potency assay and the results of the serological potency assay (European Pharmacopoeia monograph 0870; test A). Furthermore, a high correlation between the serological data (Haemagglutination Inhibition-antibody titres) and clinical protection after challenge was demonstrated. Correlation between in vivo and in vitro potency assays was confirmed in a collaborative pre-validation study. In the pre-validation study three Official Medicines Control Laboratories (OMCLs) determined both the NDV-HN antigen content and the in vivo potency (vaccination-serology and vaccination-challenge) of 6 vaccine batches. The conclusion of the pre-validation study was that a large-scale collaborative study should be organised to validate the in vitro method and the suitability of the reference preparation. This report describes the outcome of this study. In brief, 14 laboratories (8 OMCLs and 6 vaccine manufacturers) determined the NDV-HN antigen content of 9 different vaccines in 3 independent tests. The vaccine batches were produced by 5 different manufacturers and represent a quantitative range of ND antigen content. One vaccine batch with insufficient potency and one poultry vaccine not containing NDV were included. Statistical evaluation of the results indicated that the antigen content could be determined with high precision. A good repeatability as well as reproducibility was found. Furthermore all laboratories found a similar ranking of the vaccines, based on the antigen content. Comparison of the antigen content and the in vivo potency of a series of vaccines with relatively low potencies indicated that a threshold relative antigen level of 7.0 antigen units per dose would discriminate between vaccine batches with sufficient and insufficient potency. An in vitro assay with this threshold level for antigen content did not result in any false positive results and only a limited number of false negative results in the BSP055 study. We conclude that the in vitro measurement of the antigen content of inactivated ND-vaccines with the proposed method is a reliable alternative potency assay that could be included as a new method in monograph 0870 on ND-vaccines.

Establishment of batch 4 of the Biological Reference Preparation (BRP) for rabies vaccine (inactivated) for veterinary use

9 laboratories from 7 countries including both laboratories from the public and private sector participated in a collaborative study organised under the aegis of the European Directorate for the Quality of Medicines Biological Standardisation Programme in order to establish batch 4 of the European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for rabies vaccine (inactivated) for veterinary use. Establishment of Ph. Eur. BRP batch 4 was necessary in order to replace Ph. Eur. BRP batch 3, the stocks of which were dwindling. 8 laboratories provided results. Ph. Eur. BRP batch 4 was calibrated against the 5th International Standard for inactivated rabies vaccine in International Units (IU) using the vaccination challenge method of the Ph. Eur. monograph 0451. The International Standard (IS), Ph. Eur. BRP batch 4 and batch 3 are all freeze-dried vaccines prepared by beta-propiolactone inactivation of the Pitman Moore strain of rabies. Based on the results of the study, a potency of 11 IU/vial was assigned to Ph. Eur. BRP batch 4 for rabies vaccine (inactivated) for veterinary use. Nevertheless, it was noted that the vaccination challenge assay used as the "golden standard" for potency determination of inactivated rabies vaccines for veterinary use is a crude assay requiring the use of a large number of animals. Evidence from this study and from the collaborative study to establish Ph. Eur. BRP batch 3 suggests that the assay is difficult to perform and provides highly variable results. The validation of a suitable in vitro alternative is therefore highly recommended, as is the possible improvement of the in vivo assay, which will most likely remain the "golden" standard.

Establishment of European Pharmacopoeia (Ph. Eur.) Biological Reference Preparations (BRP) batch 2 for rDNA hepatitis B vaccine (method A and B)

A collaborative study was initiated by the European Directorate for the Quality of Medicines (EDQM), to assign a potency value for candidate batch 2 of European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for Hepatitis B (rDNA) antigen in vitro assays, for both method A and method B by calibrating them against the Ph. Eur. BRPs, batch 1 for methods A and B respectively. The study was prompted by the observation that the first batch of BRP for method B appeared to have lost potency over time. BRP 1 for method A showed no loss in potency, however stocks of the material were nearing depletion. Eleven laboratories participated in the study and all reported results. Participants performed 3 independent assays using both method A and method B. Method A was used to assess BRPs for method A and method B was used to assess BRPs for method B. Since BRP 1B was suspected to have lost potency, an additional sample was included in the method B test in an attempt to clarify the situation. BRP 1B was also assayed in method A against BRP 1A in the hope of also attaining further information by comparing the results from this study to those obtained in the original study to establish the first batch of BRP [1]. Although it was not the primary aim of this study to correlate in vitro potency with the immunogenicity assay in mice, a number of interested parties also performed the mouse in vivo assay to obtain data on the behaviour of the candidate BRPs in this assay. For method A, potency estimates were satisfactory in terms of repeatability and reproducibility. The candidate material was therefore assigned a value of 16.6 micrograms/ml. For method B, it appeared that the observation of reduced in vitro potency of BRP1 was confirmed. Despite the attempt to clarify the situation with additional studies, it was not possible to assign a potency value with the results obtained. A small-scale collaborative study will be organised to determine an appropriate value for the candidate BRP for method B. The results from the in vivo study while highly variable showed no evidence of a shift in the in vivo potency for either BRP 1A or BRP 1B. It should be noted that the in vitro method for determination of hepatitis B vaccine potency is under revision due to the discontinuation of the Auszyme kit from Abbott, which is required to perform the current assays. Once an alternative assay has been established, the suitability of the reference preparations or establishment of new reference preparations will be required. The candidate material for method A BRP was adopted by the European Pharmacopoeia Commission at its session in November 2003, as the European Pharmacopoeia Hepatitis B vaccine (rDNA) method A, batch 2.

Reduction in heat-induced gastrointestinal hyperpermeability in rats by bovine colostrum and goat milk powders

Male Sprague-Dawley rats were assigned to one of three dietary groups [standard diet (Cont; n = 8), standard diet plus bovine colostrum powder (BColost 1.7 g/kg; n = 8), or goat milk powder (GMilk 1.7 g/kg; n = 8)] to determine the ability of these supplements to reduce gastrointestinal hyperpermeability induced by heat. Raising core body temperature of rats to 41.5 degrees C increased transfer of (51)Cr-EDTA from gut into blood 34-fold relative to the ambient temperature value (P < 0.05) in the Cont group of rats, indicative of increased gastrointestinal permeability. Significantly less (P < 0.01) (51)Cr-EDTA was transferred into the blood of rats in either the BColost (27% of Cont) or GMilk group (10% of Cont) after heating, showing that prior supplementation with either bovine colostrum or goat milk powder significantly reduced the impact of heat stress on gastrointestinal permeability. The changes in the BColost group were not significantly different than those of the GMilk group. The potential mechanism of the protective effect of bovine colostrum and goat milk powders may involve modulation of tight junction permeability, because both powders were able to maintain transepithelial resistance in Madin Darby canine kidney cells challenged with EGTA compared with cells maintained in media only. The results show that bovine colostrum powder can partially alleviate the effects of hyperthermia on gastrointestinal permeability in the intact animal. Moreover, goat milk powder was equally as effective as bovine colostrum powder, and both may be of benefit in other situations where gastrointestinal barrier function is compromised.

Feasibility study to evaluate the correlation between results of a candidate in vitro assay and established in vivo assays for potency determination of Newcastle disease vaccines

A Newcastle disease virus antigen quantification assay has been developed at CIDC-Lelystad as a candidate in vitro potency test for inactivated Newcastle disease vaccines. In studies performed at CIDC-Lelystad, a high correlation was demonstrated between the results of this candidate in vitro potency assay and the results of the serological potency assay (European Pharmacopoeia monograph 0870; test A). Furthermore, a high correlation between the serological data (Haemagglutination Inhibition-antibody titres) and clinical protection after challenge was demonstrated. The aim of the feasibility study was to confirm the correlation between the results obtained using the candidate in vitro potency assay and the results from both the in vivo potency assays currently prescribed in Ph Eur monograph 0870, in different laboratories and to determine whether a large-scale validation study of the in vitro method should ensue. In the feasibility study three Official Medicines Control Laboratories tested the potency of 5 different inactivated Newcastle disease vaccines and one experimental vaccine, using both of the in vivo methods described in the European Pharmacopoeia and the candidate in vitro method. The 6 vaccine batches represented a quantitative range of Newcastle disease virus antigen content and were produced by different manufacturers. Statistical evaluation of all results indicated that a satisfactory correlation was found in all laboratories between the two types of in vivo tests currently in place, and the candidate in vitro test. An excellent reproducibility of the proposed in vitro method was observed with respect to the ranking of the vaccines included in this study. It is concluded that the results of this feasibility study indicate that a large-scale collaborative study can be organised to validate the in vitro method and the suitability of the reference preparation.

Establishment of European Pharmacopoeia BRP batch 2 for inactivated poliomyelitis vaccine for in vitro D antigen assay

A collaborative study was initiated by the European Directorate for the Quality of Medicines (EDQM) to assign a potency value for the candidate Ph Eur BRP batch 2 against the 2nd International Standard (IS) in order to replace the dwindling stocks of Ph Eur BRP batch 1. The candidate material is a concentrated trivalent bulk (Type 1 (Mahoney), Type 2 (MEF1) and Type 3 (SAUKETT)) from a commercially available IPV vaccine. Nine laboratories participated in the collaborative study. Eight laboratories reported results. Participants performed in-house ELISA assays on the candidate BRP, the 2nd International Standard (IS) and the current BRP (BRP batch 1). An additional sample was included to acquire information on the correlation between the in vitro and in vivo assays based on comparison with a previous study. Results of that comparison are included as an annex. Potency estimates were satisfactory in terms of repeatability and reproducibility, however the estimates for the 2nd IS were significantly lower than those for Ph Eur BRP batch 1. These two reference standards are derived from the same material and were originally assigned the same potency value after a joint study run by EDQM and the WHO in 1994. A reconciliation study was therefore designed to determine if the IS stored at NIBSC and the IS which had been sent from NIBSC to EDQM for use in the initial study were equivalent. 3 of the laboratories from the initial study participated. Results revealed no significant difference between the 2nd IS stocks stored in the two different locations at NIBSC nor between BRP batch 1 and the standards stored at NIBSC for types 1 and 2. For type 3 the 2nd IS standards stored at NIBSC are 13 % less potent than the Ph Eur BRP batch 1. The 2nd IS which had been shipped from NIBSC to EDQM was significantly less potent than BRP batch 1 and the 2nd ISs stored at NIBSC for all three types, confirming the observation of the initial study. Possible explanations for this apparent loss of potency of the 2nd IS used in the study are under investigation. Since Ph Eur BRP batch 1 and the 2nd IS in stock at NIBSC appear no more different than when their original potency assignment was made at their establishment, and since the 2nd IS standard used in the initial part of this study was compromised, a consensus potency value for the candidate BRP was determined using Ph Eur BRP batch 1 as the reference standard. The candidate material was therefore assigned a potency of 320-67-282 D Antigen units/ml (IU) for types 1, 2 and 3 respectively. A stability monitoring program will be initiated. The candidate material was adopted by the European Pharmacopoeia Commission at its session in March 2003 as European Pharmacopoeia IPV vaccine BRP batch 2 for D Ag in vitro assay.

Mitochondrial DNA decrease in subcutaneous adipose tissue of HIV-infected individuals with peripheral lipoatrophy

OBJECTIVE

To determine whether the peripheral fat wasting (lipodystrophy), which is seen in association with highly active antiretroviral therapy (HAART) that includes a nucleoside reverse transcriptase inhibitor (NRTI), is associated with a decrease in subcutaneous adipose tissue mitochondrial DNA (mtDNA) content or with large mtDNA deletions or insertions.

DESIGN

A four cohort cross-sectional study.

METHODS

The mtDNA content of subcutaneous fat tissue from the neck, abdomen and thigh was determined by polymerase chain reaction utilizing the amplification of three different mtDNA fragments. The results from HIV-infected patients with peripheral fat wasting following more than 6 months of NRTI-containing HAART were compared with the results from three different control cohorts: HIV-infected patients with a similar treatment history without lipodystrophy; HIV-infected patients naive to antiretroviral therapy and HIV sero-negative participants.

RESULTS

A decrease in mtDNA content was found in HAART-treated HIV-infected patients with peripheral fat wasting in comparison with subjects in the control cohorts. No large mitochondrial deletions or insertions were found.

CONCLUSIONS

Lipodystrophy with peripheral fat wasting following treatment with NRTI-containing HAART is associated with a decrease in subcutaneous adipose tissue mtDNA content.

Collaborative study for the establishment of erysipelas ELISA coating antigen. European Biological Reference Preparation batch no. 1

The development and validation of suitable alternatives for the replacement of in vivo challenge testing in the evaluation of vaccines is an important goal for national authorities and manufacturers involved in the assessment of quality, safety and efficacy of such products. To that end, 13 laboratories from 9 European countries, including 5 manufacturers, 7 authorities and EDQM, have taken part in a collaborative study to evaluate the suitability of a candidate reference preparation of erysipelas coating antigen for ELISA as a European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP No. 1). The new Ph. Eur. BRP is intended for use in a serological assay, which would significantly reduce the suffering of animals in the potency assays of inactivated erysipelas vaccines. Participants were provided with sufficient study material, including the candidate coating antigen, and a panel of test sera from mice which had been immunised with vaccines representative of products on the European market, in order to evaluate the performance of the coating antigen in an enzyme-linked immunosorbent assay (ELISA) which had previously performed successfully in a prevalidation study [1] and in an international validation study [2]. Results of the collaborative study indicate that the candidate batch of erysipelas ELISA coating antigen is suitable to act as a Ph. Eur. biological reference preparation. The final study report was presented at the 110th session of the Ph. Eur. Commission (June 19-21, 2001) and the material was duly adopted as Erysipelas ELISA Coating Antigen Ph. Eur. BRP No. 1 for use in the enzyme-linked immunosorbent assay in the context of the serological potency assay for inactivated erysipelas vaccines.

Medical issues relating to the Sydney Olympic Games

The Sydney Olympic Games in 2000 represent a significant medical and sporting challenge. Prior planning is the key to optimal performance, and team medical staff should be familiar with major medical and injury concerns of athletes and officials well prior to departure. A comprehensive team medical kit should be organised. Travel will be over great distances for many teams, so particular attention to optimising sleep and hydration is essential. The Olympic village experience can be overwhelming for some athletes, and medical staff should provide informed advice on food, transport and safety issues. Heat is less likely to be an issue than at recent summer Olympic Games, but should not be ignored completely. Major incidents can occur at any major sporting festival, and team medical staff should be appropriately prepared for these. All team medical staff should be aware of the current list of banned substances, and seek to minimise drug use by their athletes. After the event, an appropriate debriefing session should be held with a view to planning improvements for the future.

Problem-solving counseling for caregivers of the cognitively impaired: effective for whom?

BACKGROUND

Individualized problem-solving counseling for caregivers of cognitively impaired relatives is thought to help caregivers cope with the stress and burden of caregiving. Few studies have shown the effectiveness of counseling for these caregivers.

OBJECTIVES

To determine the effectiveness of individualized problem-solving counseling by nurses for caregivers and the expenditures of health care utilization.

METHOD

Caregivers (n = 77) of the cognitively impaired living at home were randomized to receive nurse counseling or not. Psychosocial adjustment to their relative's illness, psychological distress, burden, coping skills, and expenditures were measured after 6 months and 1 year.

RESULTS

Although on average, all caregivers receiving nurse counseling indicated no improvement in psychosocial adjustment to their relative's illness, psychological distress, or caregiver burden, they found counseling very helpful and it was effective for a subgroup of caregivers. Those with poor logical analysis coping skills at baseline had decreased psychological distress (F(1,53) = 9.7, p = .003) and improved psychosocial adjustment (F(1,53) = 4.7, p = .035) after 1 year. Caregivers in control and counseling groups whose relatives entered a nursing home improved their psychosocial adjustment 23% on average whereas those continuing to live in the community decreased by 8%. Almost half as many relatives entered nursing homes in the counseling group (n = 9 vs. n = 5) but these compared to control group relatives had greater annualized per person expenditures for health and social services (Cdn$23,437 vs. Cdn$15,151).

CONCLUSIONS

Caregivers found nurse counseling most helpful. Those indicating infrequent use of logical analysis coping skills showed benefits.