Passive hemagglutination test for measles immunity and serodiagnosis

Sero-epidemiology and Risk Factor Analysis of Measles Among Children in Pakistan

Comparative cross sectional study was conducted on blood samples (n = 231) collected from children of 1 to 10 years of age in Punjab Pakistan through convenient sampling method. Indirect haemagglutination assay (IHA) was standardized and used for serodiagnosis and evaluation of humoral immunity against measles. Associated risk factors including age, gender, locale, and vaccination status were analyzed. Geometric mean titre (GMT) of vaccinated individuals was significantly higher (p < 0.001) than that of non-vaccinated individuals showing that IHA titre of vaccinated individuals was a measure of humoral immune response; whereas, in case of non-vaccinated individuals an indicative of exposure to the measles infection.

Kinetics of measles antibody by hemagglutination inhibition assay in children in south-west and north-central Nigeria

OBJECTIVES

We investigated the antibody level of children against wild measles virus in view of recurrent measles epidemics, in order to provide information on immunization status for health policies and for the global measles mortality reduction initiative.

METHODS

Two hundred and seventy-three children between the ages of 10 months and 13 years were recruited for this study from three hospital facilities in south-west and north-central Nigeria. Serum samples were collected from February to July 2009, and laboratory examination commenced in August of the same year. Measles hemagglutinin (HA) antigen was prepared by culturing the measles vaccine virus strain (Edmonston-Zagreb) in a vero/hSLAM cell line. Serum samples were treated to get rid of potentiating factors, non-specific inhibitors, and agglutinins before the HA/hemagglutination inhibition (HI) procedure.

RESULTS

Out of the 175 children vaccinated in Ibadan, 60 (34.3%) had an antibody level not sufficient to protect against measles infection. Likewise, 12 (25.0%) vaccinated children from Ilorin had an antibody level not sufficient to protect against measles infection. There was no significant difference in the level of protection between the children in Ibadan and Ilorin (p>0.05). The geometric mean titer (GMT) was 53.83 for males and 48.64 for females. There was no significant difference between the GMTs of females and males in both locations (p>0.05). Also, no significant difference was observed in the GMTs of children in both locations (p>0.05).

CONCLUSIONS

Of the vaccinated children, 157 (57.5%) developed protective measles virus HI antibody, which is not enough to maintain protective herd immunity. Hence there is a need for catch-up and follow-up vaccination programs, especially in rural areas and places with difficult terrains, in order to reduce measles mortality.

Vaccine-induced measles virus antibodies after two doses of combined measles, mumps and rubella vaccine: a 12-year follow-up in two cohorts

In Finland, a two-dose vaccination programme against measles, mumps and rubella (MMR) was begun in 1982. The programme with high coverage (97-98%) has eliminated these three diseases from Finland. The aim of the present study was to follow up the kinetics of measles virus antibodies in MMR vaccinated cohorts. We have followed the kinetics of measles virus antibody levels induced by vaccination in the same individuals immunized with their first MMR vaccine in 1982. After 12 years 80% of the original children remained available for sampling. Antibodies to measles virus were measured by haemagglutination inhibition (HI) and plaque reduction neutralization (NT) techniques. The primary dose induced 99.4% seroconversion for measles with a geometric mean HI antibody titre (GMT) of 1/269 (+/- 219), equivalent to 4304 mIU (milli-International Units) ml-1 in group A. The 12-year follow-up specimens showed a measles seropositivity rate of 100% as assayed with the HI and NT tests with a mean HI antibody titre of 1/39 (+/- 54), equivalent to 624 mIU ml-1. The vaccination-induced measles virus antibodies decline in the absence of natural booster infections. It is important to follow how long the protection achieved by the present vaccine programme will last after elimination of indigenous measles.

Modified seroneutralization assay for measles virus antibody detection

We describe a simple, inexpensive, sensitive and specific modified seroneutralization assay for use on a wide scale to screen for the presence of measles antibodies. After only one reaction (1 h) and a 3-day incubation period at 37 degrees C, the test can be easily read using a rapid, inexpensive methylene blue/phenol staining procedure. The determination of protective antibody titres by modified and standard seroneutralization methods was strongly correlated (corr. coff. = 0.98).

Protective role of human antibody to the fusion protein of measles virus

Absorption of a pooled human gamma globulin preparation with acetone-treated measles virus-infected cells removed all antibodies to measles virus antigens except a portion of the antibody to the fusion (F) protein. The residual anti-F antibody had hemolysis-inhibiting and virus-neutralizing activities, inhibited spread of infection through cell fusion, and was effective in protection of passively immunized mice from fatal measles encephalitis, providing evidence for the protective role of human antibody to the F protein of measles virus.