BRIEF COMMUNICATIONS
A comparison of serological tests for detecting antibody to plague JAMES E. WILLIAMS,' MOHAMAD ATAS,2 & DAN C. CAVANAUGH 3
Abstract
' 80
A study was undertaken of the relationship between the passive haemagglutination and haemagglutination inhibition tests used in serum surveys for specific plague antibodies. Both techniques gave similar titres for sera of albino Rattus norvegicus convalescent from plague infection. They appear to be equally suitable for plague surveillance and control programmes. Serum surveys for specific plague antibody utilizing passive haemagglutination (HA) tests have been recommended by the World Health Organization (1) for the surveillance of rodent populations. In some countries, the haemagglutination inhibition (HI) test has also been used. Since the HI test is somewhat simpler, several developing nations have expressed interest in using this procedure in their plague control programmes. Therefore, to establish a basis for comparing results obtained in various plague foci where one or other of these procedures might be employed, a study was undertaken of the relationship between the two techniques. Sera were obtained from albino Rattus norvegicus, including untreated controls and rats previously vaccinated and recovered from challenge plague infection. Sodium azide, 0.1%, was added as preservative, and passive HA titres were determined in tests using aldehyde stabilized erythrocytes sensitized with the specific fraction 1 antigen of Yersinia pestis (2). The coded sera were then sent for HI testing to the Public Health Laboratory, Jogjakarta, Indonesia, where serological investigations using the HI technique had recently been instituted. The HI test procedure (3) employed formalinized erythrocytes sensitized with specific 1 Chief, Plague Section, Department of Hazardous Microorganisms, Division of Communicable Disease and Immunology, Walter Reed Army Institute of Research, Washington, DC 20012, USA. 2Toxicologist/Serologist, Public Health Laboratory, Jogjakarta, Indonesia. 'Chief, Department of Hazardous Microorganisms, Division of Communicable Disease and Immunology, Walter Reed Army Institute of Research, Washington, DC 20012, USA.
3513
-
40
wE
4
20 _
10 _ 5
0
w/ ^8
S
I ~~~I 16 32
I 64
I 2128
RECIPROCAL HA TITRE
Fig. 1. Correlation of two serological tests for antibody to Yersinia pestis. Each point reports titres obtained for a serum from normal or convalescent albino Rattus norvegicus.
plague serum prepared at the WHO Plague Reference Laboratory, Central-Asian Anti-Plague Institute, Alma-Ata, Zavodskaja, USSR. After the tests had been completed, HI titres were compared with the HA titres previously determined in the USA on the same vials of serum. The results (Fig. 1) demonstrated that the HI technique provided approximately the same sensitivity for detecting plague antibody as the HA procedure. A coefficient of correlation equal to 0.88 was obtained for the linear regression of titres. A geometric mean HA titre of 1:36 was obtained for sera, with individual titres ranging from 1:16 to 1:64. These same sera had a geometric mean HI titre of 1:20. The data indicate that the HI and HA techniques, with approved reagents from WHO or national plague laboratories, should provide information on the prevalence of antibody and on serum titres that are directly comparable to data from studies done elsewhere with either procedure. Both tests appear suitable for plague surveillance and control programmes.
232 -
BULL. WORLD HEALTH ORGAN., Vol. 54, 1976
BRIEF COMMUNICATIONS
233
ACKNOWLEDEMENTS
REFERENCES
The authors thank Dr B. Cvjetanovi6, World Health Organization, Geneva, Switzerland for valuable assistance. The formalinized erythrocytes sensitized with specific plague serum used in the HI test were kindly supplied by Dr A. K. Akiev, Deputy Director, Antiplague Research Institute of the Caucasus and Transcaucasia, Stavropol, USSR.
1. WHO Technical Report Series, No. 447, 1970 (Fourth report of the WHO Expert Committee on Plague). 2. WILLIAMS, J. E. ET AL. J. inf. Dis., 129: S72-S77 (1974). 3. PEYSAKHIS, L. A. & SHUMTER, M. F. [Handbook on the use of serological methods for the diagnosis of plague in the natural foci of the USSR.] Alma-Ata, USSR, 1968.
A comparison of serological tests for detecting antibody to plague JAMES E. WILLIAMS,' MOHAMAD ATAS,2 & DAN C. CAVANAUGH 3
Abstract
' 80
A study was undertaken of the relationship between the passive haemagglutination and haemagglutination inhibition tests used in serum surveys for specific plague antibodies. Both techniques gave similar titres for sera of albino Rattus norvegicus convalescent from plague infection. They appear to be equally suitable for plague surveillance and control programmes. Serum surveys for specific plague antibody utilizing passive haemagglutination (HA) tests have been recommended by the World Health Organization (1) for the surveillance of rodent populations. In some countries, the haemagglutination inhibition (HI) test has also been used. Since the HI test is somewhat simpler, several developing nations have expressed interest in using this procedure in their plague control programmes. Therefore, to establish a basis for comparing results obtained in various plague foci where one or other of these procedures might be employed, a study was undertaken of the relationship between the two techniques. Sera were obtained from albino Rattus norvegicus, including untreated controls and rats previously vaccinated and recovered from challenge plague infection. Sodium azide, 0.1%, was added as preservative, and passive HA titres were determined in tests using aldehyde stabilized erythrocytes sensitized with the specific fraction 1 antigen of Yersinia pestis (2). The coded sera were then sent for HI testing to the Public Health Laboratory, Jogjakarta, Indonesia, where serological investigations using the HI technique had recently been instituted. The HI test procedure (3) employed formalinized erythrocytes sensitized with specific 1 Chief, Plague Section, Department of Hazardous Microorganisms, Division of Communicable Disease and Immunology, Walter Reed Army Institute of Research, Washington, DC 20012, USA. 2Toxicologist/Serologist, Public Health Laboratory, Jogjakarta, Indonesia. 'Chief, Department of Hazardous Microorganisms, Division of Communicable Disease and Immunology, Walter Reed Army Institute of Research, Washington, DC 20012, USA.
3513
-
40
wE
4
20 _
10 _ 5
0
w/ ^8
S
I ~~~I 16 32
I 64
I 2128
RECIPROCAL HA TITRE
Fig. 1. Correlation of two serological tests for antibody to Yersinia pestis. Each point reports titres obtained for a serum from normal or convalescent albino Rattus norvegicus.
plague serum prepared at the WHO Plague Reference Laboratory, Central-Asian Anti-Plague Institute, Alma-Ata, Zavodskaja, USSR. After the tests had been completed, HI titres were compared with the HA titres previously determined in the USA on the same vials of serum. The results (Fig. 1) demonstrated that the HI technique provided approximately the same sensitivity for detecting plague antibody as the HA procedure. A coefficient of correlation equal to 0.88 was obtained for the linear regression of titres. A geometric mean HA titre of 1:36 was obtained for sera, with individual titres ranging from 1:16 to 1:64. These same sera had a geometric mean HI titre of 1:20. The data indicate that the HI and HA techniques, with approved reagents from WHO or national plague laboratories, should provide information on the prevalence of antibody and on serum titres that are directly comparable to data from studies done elsewhere with either procedure. Both tests appear suitable for plague surveillance and control programmes.
232 -
BULL. WORLD HEALTH ORGAN., Vol. 54, 1976
BRIEF COMMUNICATIONS
233
ACKNOWLEDEMENTS
REFERENCES
The authors thank Dr B. Cvjetanovi6, World Health Organization, Geneva, Switzerland for valuable assistance. The formalinized erythrocytes sensitized with specific plague serum used in the HI test were kindly supplied by Dr A. K. Akiev, Deputy Director, Antiplague Research Institute of the Caucasus and Transcaucasia, Stavropol, USSR.
1. WHO Technical Report Series, No. 447, 1970 (Fourth report of the WHO Expert Committee on Plague). 2. WILLIAMS, J. E. ET AL. J. inf. Dis., 129: S72-S77 (1974). 3. PEYSAKHIS, L. A. & SHUMTER, M. F. [Handbook on the use of serological methods for the diagnosis of plague in the natural foci of the USSR.] Alma-Ata, USSR, 1968.
