Avian Influenza Antibody Titer Of Laying Hens in Production Phase At District Penebel Tabanan Regency

Background: The virus of Avian Influenza (AI) H5N1 has become endemic in Indonesia since 2003. In 2012, the Avian Influenza outbreak at District Penebel caused chickens mortality in large numbers. One of the efforts to prevention the Avian Influenza outbreak is by vaccination. Therefore, supporting AI vaccination program needs diagnostic methods from post-vaccinated chickens that produce antibody titer by Hemagglutination Inhibition (HI) test. Purpose: The study aims to monitor the antibody of Avian Influenza phase I and phase II production in laying hens at District Penebel, Tabanan Regency. Method: 131 serum samples were collected from hens serums at poultry which has been sampled before. The serum sample is tested by Hemagglutination Inhibition (HI) test to calculate antibody titer. The serum is protective if the titer reacheas 24 or more, and the serum is unprotective if the titer is under 24. Data presented in 2x2 cross-sectional study contingent tabel and analyzed by Chi-Square (X2) non-parametric with the distribution. Results: Protective percentage of immunity level in production phase I in laying hens at District Penebel is 60,3%, whereas on production phase II is 43,6%. Data from the 2x2 contingent table showed an odd ratio of 1,9. The result of the Chi-Square (X2) analysis statistic represents immunity levels between production phase I and II are non-significance (p>0,05). Conclusion: Production phase I in laying hens has an immunity level 1,9x higher than production phase II. There is an association between the production phase and the protective immunity level of Avian Influenza.

Association between hemagglutination inhibition antibody titers and protection against RT-PCR confirmed influenza illness in children 6−35 months of age: statistical evaluation of a correlate of protection

Background Data from a randomized, controlled efficacy trial of an inactivated quadrivalent influenza vaccine in children 6−35 months of age were used to determine whether hemagglutination inhibition (HI) antibody titer against A/H1N1 and A/H3N2 is a statistical correlate of protection (CoP) for the risk of RT-PCR-confirmed influenza associated with the corresponding strain. Methods The Prentice criteria were used to statistically validate strain-specific HI antibody titer as a CoP. The probability of protection was identified using Dunning's model corresponding to a pre-specified probability of protection at an individual level. The group level protective threshold was identified using Siber's approach, leading to unbiased predicted vaccine efficacy (VE). A case-cohort sub-sample was used for this exploratory analysis. Results Prentice criteria confirmed that HI titer is a statistical CoP for RT-PCR-confirmed influenza. Dunning's model predicted a probability of protection of 49.7% against A/H1N1 influenza and 54.7% against A/H3N2 influenza at an HI antibody titer of 1:40 for the corresponding strain. Higher titers of 1:320 were associated with more than 80% probability of protection. Siber's method predicted VE of 61.0% at a threshold of 1:80 for A/H1N1 and 46.6% at 1:113 for A/H3N2. Conclusions The study validated HI antibody titer as a statistical CoP, by demonstrating that HI titer is correlated with clinical protection against RT-PCR-confirmed influenza associated with the corresponding influenza strain and is predictive of VE in children 6−35 months of age.

A competitive hemagglutination inhibition assay for dissecting functional antibody activity to influenza virus

Influenza remains one of the most contagious infectious diseases. Approximately, 25-50 million people suffer from influenza-like illness in the United States annually, leading to almost 1 million hospitalizations. Globally, the World Health Organization (WHO) estimates 250,000-500,000 mortalities associated with secondary respiratory complications due to influenza virus infection every year. Currently, seasonal vaccination represents the best countermeasure to prevent influenza virus spread and transmission in the general population. However, presently licensed influenza vaccines are about 60% effective on average, and their effectiveness varies from season to season and among age groups, as well as between different influenza subtypes within a single season. The hemagglutination inhibition (HAI) assay represents the gold standard method for measuring the functional antibody response elicited following standard-of-care vaccination, along with evaluating the efficacy of under-development influenza vaccines in both animal models and clinical trial settings. However, using the classical HAI approach it is not possible to dissect the complexities of variable epitope recognition within a polyclonal antibody response. In this communication, we describe a straightforward competitive HAI-based method using a combination of influenza virus and recombinant hemagglutinin (HA) proteins to dissect the HAI functional activity of HA-specific antibody populations in a single assay format. Importance: The hemagglutination inhibition (HAI) assay is a well-established and reproducible method that quantifies functional antibody activity against influenza viruses and in particular the capability of an antibody formulation to inhibit the binding of HA to sialic acid. However, the HAI assay does not provide with full insights on the breadth and epitope recognition of the antibody formulation, especially in the context of polyclonal sera where multiple antibody specificities contribute to the overall observed functional activity. In this report we introduce the use of Y98F point-mutated recombinant HA (HAΔSA) proteins, which lack sialic acid binding activity, in the context of the HAI assay as a mean to absorb out certain HA-directed (i.e., strain-specific or cross-reactive) antibody populations. This modification to the classical HAI assay, referred to as the competitive HAI assay, represents a new tool to dissect the magnitude and breadth of polyclonal antibodies elicited through vaccination or natural infection.

Serological Surveillance of Influenza D Virus in Ruminants and Swine in West and East Africa, 2017–2020

Influenza D virus (IDV) was first isolated in 2011 in Oklahoma, USA from pigs presenting with influenza-like symptoms. IDV is known to mainly circulate in ruminants, especially cattle. In Africa, there is limited information on the epidemiology of IDV, although the virus has likely circulated in the region since 2012. In the present study, we investigated the seropositivity of IDV among domestic ruminants and swine in West and East Africa from 2017 to 2020. Serum samples were analyzed using the hemagglutination inhibition (HI) assay. Our study demonstrated that IDV is still circulating in Africa, with variations in seropositivity among countries and species. The highest seropositivity was detected in cattle (3.9 to 20.9%). Our data highlights a need for extensive surveillance of IDV in Africa in order to better understand the epidemiology of the virus in the region.

Assay Harmonization and Use of Biological Standards To Improve the Reproducibility of the Hemagglutination Inhibition Assay: a FLUCOP Collaborative Study

The hemagglutination inhibition (HAI) assay is the most commonly used serology assay to detect antibodies from influenza vaccination or influenza virus infection. This assay has been used for decades but requires improved standardization of procedures to provide meaningful data.

Seroprevalence of mycoplasmosis in broiler, layer, and native chickens in Giza, Egypt

We aimed to investigate Mycoplasma infections among chicken flocks (Ross, Lohmann and native) in Giza, Egypt, using serological tests, including the slide plate agglutination (SPA) test, hemagglutination inhibition (HI) test, and enzyme-linked immunosorbent assay (ELISA). The slide plate agglutination examination, a serological test, indicated the prevalence of Mg and Ms infections of 10.9% and 13.2%, respectively. On 91 SPA test positive serum samples for either Mg or Ms, a passive hemagglutination/hemagglutination inhibition (HI) test was performed. The SPA and HI test findings were found to be comparable. On 90 SPA test positive samples, an ELISA was performed using commercial kits for Mg and Ms serodiagnosis. According to the ELISA data, only 83.33% and 18.88% of SPA test positive samples were confirmed as positive for Ms and Mg infections, respectively. The prevalence increased to 84.44% and 77.77%, respectively, when suspected samples were deemed positive.

Identification and Quantification of Anti-Gp.Mur Antibodies in Human Serum Using an Insect-Cell-Based System

Gp.Mur is a clinically relevant antigen of the MNS blood group system that is highly prevalent in several Asian populations. Its corresponding antibody, anti-Gp.Mur, has been implicated in hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. Currently, identifying and confirming anti-Gp.Mur antibody presence in sera via agglutination of a panel of red blood cells (RBCs) is inefficient and difficult to quantify. Using a baculovirus expression system to express Gp.Mur antigen on insect cell surfaces, we have developed a quantitative cell-based system to confirm the presence of anti-Gp.Mur antibody in human serum. We obtained 10 serum samples preidentified as having anti-Gp.Mur antibody and another 4 samples containing noncorresponding antibodies from hospital patients. Insect cells displaying Gp.Mur antigen successfully adsorbed anti-Gp.Mur antibody in the sera and inhibited the RBC agglutination mediated by this antibody. By varying the concentration of Gp.Mur-displaying cells, we could grade levels of RBC agglutination by anti-Gp.Mur antibody. Densitometric analysis further enabled quantitative determinations of hemagglutination inhibition by Gp.Mur-displaying cells. We believe that this cell-based hemagglutination inhibition system greatly improves or supplements existing technology and is a convenient means for accurately identifying and quantifying anti-Gp.Mur antibody.