Epidemiology of Newcastle disease in chickens of Ethiopia: a systematic review and meta-analysis.

The objective of this systematic review was to estimate the overall pooled prevalence of Newcastle disease in chickens in Ethiopia and identify the sources of heterogeneity among and within studies. The seroprevalence of Newcastle disease was estimated using a single-group meta-analysis. Attempts were also made to identify study-level variables that could explain the heterogeneity in the apparent seroprevalence of the Newcastle disease. The findings were based on 16 published articles and 33 district-level reports and were limited to studies performed during 2005-2017. Due to the presence of heterogeneity, pooled analysis from different districts was conducted using random-effects meta-analysis. The single-group summary of Newcastle disease seroprevalence in chickens was estimated to be 21.47% (19.54-23.4%) with a 95% confidence interval. Our results indicated high inter-study variability (Cochran's Q statistic = 196.2, true variance (τ2) = 0.36, inverse variance index (I2) = 90.0%, p < 0.001). Of all variables analysed, diagnostic techniques and regions were the most significant predictors (p ˂ 0.05) of heterogeneity. According to the diagnostic technique-based meta-analysis of random pooled prevalence, the haemagglutination inhibition test had the highest prevalence, followed by the enzyme-linked immunosorbent assay. In conclusion, the high-pooled prevalence estimates of the disease, combined with the scarcity of published data for the entire country of Ethiopia, indicate a significant data gap on the distribution of Newcastle disease in the country. While the high pooled prevalence tells the need for intervention to control the disease, there is also a need to assess the disease prevalence in all other parts of the country.

Alternating 3 different influenza vaccines for swine in Europe for a broader antibody response and protection.

Heterologous prime-boost vaccination with experimental or commercial influenza vaccines has been successful in various animal species. In this study, we have examined the efficacy of alternating 3 different European commercial swine influenza A virus (swIAV) vaccines: the trivalent Respiporc® FLU3 (TIV), the bivalent GRIPORK® (BIV) and the monovalent Respiporc® FLUpan H1N1 (MOV). Five groups of 6 pigs each received 3 vaccinations at 4-6 week intervals in a homologous or heterologous prime-boost regimen. A sixth group served as a mock-vaccinated challenge control. Four weeks after the last vaccination, pigs were challenged intranasally with a European avian-like H1N1 (1C.2.1) swIAV, which was antigenically distinct from the vaccine strains. One heterologous prime-boost group (TIV-BIV-MOV) had higher hemagglutination inhibition (HI) and neuraminidase inhibition antibody responses against a panel of antigenically distinct H1N1, H1N2 and H3N2 IAVs than the other heterologous prime-boost group (BIV-TIV-MOV) and the homologous prime-boost groups (3xTIV; 3xBIV; 3xMOV). Group TIV-BIV-MOV had seroprotective HI titers (≥ 40) against 56% of the tested viruses compared to 33% in group BIV-TIV-MOV and 22-39% in the homologous prime-boost groups. Post-challenge, group TIV-BIV-MOV was the single group with significantly reduced virus titers in all respiratory samples compared to the challenge control group. Our results suggest that the use of different commercial swIAV vaccines for successive vaccinations may result in broader antibody responses and protection than the traditional, homologous prime-boost vaccination regimens. In addition, the order in which the different vaccines are administered seems to affect the breadth of the antibody response and protection.

Assessment of the hemagglutinating activity of the Porcine orthorubulavirus.

Blue eye disease (BED) in pigs is caused by Porcine orthorubulavirus (PRV) of the Paramyxoviridae family. It is an endemic disease in swine production in the central region of Mexico and causes nervous signs and high mortality in suckling pigs, pneumonia in growing pigs, orchitis in boars and mummification during gestation. PRV hemagglutinates most red blood cells (RBCs) of domestic species. For serological diagnosis, the hemagglutination inhibition test is used, and in this test, guinea pig, bovine and chicken RBCs have been commonly used. In this investigation, hemagglutination with PRV was evaluated using the RBCs of seven domestic species (chicken, bovine, horse, pig, dog, guinea pig and rabbit). In the hemagglutination test, the following parameters were evaluated: temperature (25 °C and 37 °C), bottoms of the wells (V and U), erythrocyte concentration (0.5%, 0.75%, and 1%), and reading time (15, 30, 45, 60 and 90 min). Significant differences (P < 0.001) were found in most of the evaluated treatments. The best hemagglutination results were obtained with chicken, bovine and horse RBCs. The hemagglutination titer is higher (2 dilutions) when using chicken RBCs than when using bovine or horse RBCs. If chicken RBCs are used in the inhibition of hemagglutination, the test will be more sensitive, while it is more specific when bovine or horse RBCs are used. The hemagglutination readings are imprecise when using RBCs from dogs, pigs, guinea pigs and rabbits. RBCs from these species should not be used for the diagnosis or investigation of PRV.

Pathology of Komarov vaccine in Hitchner B1 vaccinated and unvaccinated broilers.

Newcastle disease (ND) is a major problem of poultry production worldwide. Control is by biosecurity and vaccination. In this project, we studied the pathology of Komarov vaccine which is commonly used in many countries of Africa on the Hitchner B1 (HBI) vaccinated and unvaccinated broilers. Seventy-five Arbor Acres broilers were obtained at 1 day old. Twenty-five of the broilers were given HB1 vaccine at the hatchery and Komarov vaccine at 5 weeks of age (group HK). A second group of 25 broilers were given only Komarov vaccine at 5 weeks of age (group K). The third group remained as unvaccinated (UU). All the groups were observed for clinical signs and lesions. Depression, sneezing, coughing and noisy respiration were observed in group K broilers from day 2 post Komarov vaccination (PKV). Leg paralysis occurred in 6 broilers on day 8 PKV. The clinical signs were milder in the HK broilers. Only one broiler showed leg paralysis in this group on day 18 PKV. No mortality occurred in the three groups. The bursa, spleen and thymus showed mild to moderate enlargement, atrophy and depletion of lymphocytes on days 3, 5, 8 and 14 PKV in HK and K groups. The trachea and lungs were congested. The haemagglutination inhibition (HI) antibody titres in the K group were higher than those of HK and UU groups on days 7, 24 and 21 PKV. The above observations show that Komarov vaccine may cause no mortality in vaccinated and unvaccinated broilers and higher HI antibodies are produced in broilers that have not been vaccinated earlier.

Antibody Response of an H9 Subtype Avian Influenza Poultry Vaccine on Three Kinds of Wild Birds in Shanghai Zoo.

A semiannual immunization with a commercial inactivated H9 subtype avian influenza virus (AIV) vaccine developed for poultry has been used to prevent and control the avian influenza (AI) infections among captured wild birds in Shanghai Zoo. However, the overall safety and effectiveness of the poultry vaccine for housed birds in the zoo remain unclear. To verify the safety and efficacy of the commercial inactivated H9 AI vaccine on zoo birds and to explore a more reasonable and effective immunization procedure, 48 zoo birds, including 11 Oriental white storks, 25 peafowl, and 12 silver pheasants, were administered the AI vaccine developed for poultry use. Then, the clinical signs of the immunized birds were observed for 2 weeks, and the antibodies against H9 AI were determined via the hemagglutination inhibition test. Results showed that no harmful effects related to the vaccination were observed, and the antibody titers of the Oriental white stork, peafowl, and silver pheasants were all higher than 7 log 2 at 21 days, 30 days, 60 days, 120 days, and 180 days postimmunization. For further study, the H9 AIV titers of 11 peafowls and 6 Oriental storks, which were raised in the nursing ground, were continuously monitored for 15 months. All of their antibody titers were above the national standards of China (5 log 2; GB/T18936-2003), even at 12 months and 15 months postimmunization. We concluded that the commercial inactivated H9 AI vaccine used at the present time in Shanghai Zoo can induce high and prolonged immune responses in vaccinated birds.

Artículo regular­Respuesta de anticuerpos de una vacuna contra influenza aviar subtipo H9 en tres tipos de aves silvestres en el zoológico de Shanghai. Se ha utilizado una inmunización semestral con una vacuna comercial inactivada contra el virus de la influenza aviar del subtipo H9 (AIV) desarrollada para la avicultura comercial para prevenir y controlar las infecciones por influenza aviar (IA) entre aves silvestres cautivas en el zoológico de Shanghai. Sin embargo, la seguridad y eficacia generales de la vacuna avícola para las aves alojadas en el zoológico siguen sin estar completamente determinadas. Para verificar la seguridad y eficacia de la vacuna comercial contra la influenza aviar H9 inactivada en las aves de zoológico y para explorar un procedimiento de inmunización más razonable y eficaz, una vacuna contra la influenza desarrollada para su uso en avicultura comercial se administró a 48 aves de zoológico, incluyendo 11 cigüeñas blancas orientales, 25 pavos reales y 12 faisanes plateados. Posteriormente, se observaron los signos clínicos de las aves inmunizadas durante 2 semanas y se determinaron los anticuerpos contra el subtipo H9 del virus de influenza aviar mediante la prueba de inhibición de la hemaglutinación. Los resultados mostraron que no se desarrollaron efectos nocivos relacionados con la vacunación, y los títulos de anticuerpos de la cigüeña blanca oriental, el pavo real y los faisanes plateados fueron todos superiores a 7 log2 a los 21 días, 30 días, 60 días, 120 días y 180 días posinmunización. Para un estudio adicional, los títulos contra el subtipo H9 de 11 pavos reales y 6 cigüeñas orientales que se criaron en el área de recría, se evaluaron continuamente durante 15 meses. Todos sus títulos de anticuerpos estaban por encima de los estándares nacionales de China (5 log2; GB/T18936-2003), incluso a los 12 y 15 meses posteriores a la inmunización. Se concluye que la vacuna comercial de influenza aviar inactivada con el subtipo H9 que se utiliza actualmente en el zoológico de Shanghai puede inducir respuestas inmunitarias elevadas y prolongadas en las aves vacunadas.

Comparison of hemagglutination inhibition tests, immunoperoxidase monolayer assays, and serum neutralizing tests in detecting antibodies against blue eye disease in pigs.

Blue eye disease (BED) of pigs was identified in the early 1980s in La Piedad, Michoacan, Mexico. The causal agent is Porcine orthorubulavirus (PRV), which affects pigs of all ages, producing nervous, respiratory, and reproductive disorders. BED is geographically endemic to the center of Mexico, where 75% of the country's swine industry is concentrated. Due to its adverse effects on the swine industry and the risk of dissemination to other countries, it is essential to have reliable diagnostic methods for BED. The objective of this study was to establish the optimal conditions for three serological tests, hemagglutination inhibition (HI), immunoperoxidase monolayer assay (IPMA), and serum neutralization (SN), and to compare their sensitivity, specificity, kappa coefficient, and predictive values. Twelve different HI protocols (9408 tests), one SN protocol and one IPMA protocol (784 tests, each) were evaluated. Forty-nine sera were analyzed, and thirty-seven sera showed true positive results, while twelve showed true negative results. The kappa coefficient was used to assess the variation in each test. The best HI protocol registered a sensitivity and specificity of 89 and 100%, respectively, the IPMA test showed values of 85 and 100%, and the SN test registered a sensitivity of 91% and a specificity of 96%. One of the disadvantages of the HI test is that when chicken red blood cells (RBCs) are used, elution occurs in a short incubation time, which would decrease the specificity. The use of bovine RBCs increases the specificity of the testy and makes it more stable, but it decreases the sensitivity. The results of HI and SN revealed the importance of eliminating the complement system of the serum and removing other inhibitors to avoid test nonspecificity. The IPMA test does not use an active virus; hence, it is considered safe and does not present any risk of disseminating PRV.

Modified haemagglutination inhibition assay for the detection of canine parvovirus type 2 antibodies in dog sera.

Canine parvovirus type 2 (CPV-2) infection is associated with severe gastroenteritis in puppies. Quantification of CPV-2 specific antibodies before vaccination can reveal the presence of interfering maternal-derived immunity and facilitate timing of effective immunisation. Inhibition of haemagglutination (HI) is commonly used to measure CPV-2-specific antibody levels in serum. However, the presence of nonspecific agglutinins in canine serum and artefactual precipitation of red blood cells (RBC) are both limitations of the assay. In this study, we compared the standard HI protocol with a refined HI protocol, in which canine serum was pre-incubated with porcine RBC for 12 h to remove nonspecific agglutinins and a lower concentration (0.1% vs. 0.8%) of porcine RBC suspensions was used to limit artefactual precipitation of RBC. A panel of canine sera, collected from 80 dogs of different ages and with different neutralising antibody titres, was analysed. Nonspecific agglutinins were identified in most (97%) serum samples from puppies <4 months of age and in only 7% dogs 6 months old. Pre-treatment of serum samples was effective in removing nonspecific agglutinins from all samples and artefactual precipitation of RBCs was not noted when 0.1% RBC suspensions were used. Refinement of the HI protocol has increased the accuracy of interpretation and reduced the interference of nonspecific agglutinins, primarily seen in puppies. This reduces the likelihood of incorrect assessment of passive or active immunity in puppies when deciding whether to administer or defer vaccination, which could potentially leave them susceptible to CPV-2 infection.

Formal estimation of the seropositivity cut-off of the hemagglutination inhibition assay in field diagnosis of influenza D virus in cattle and estimation of the associated true prevalence in Morocco.

The influenza D virus (IDV) was discovered less than ten years ago. Increased interest in this virus is due to its nature (RNA virus with high mutation rate), its worldwide circulation in livestock species, its probable role in bovine respiratory disease and its zoonotic potential. Until currently, the establishment of positivity cut-off of the hemagglutination inhibition (HI) assay was not formalized in field conditions for the detection of antibodies directed against IDV in cattle (i.e. the proposed reservoir). In this study, the positivity cut-off of the HI assays was formally established (titre = 10) using a receiver operating characteristic (ROC) curve. This information was used to estimate the sensitivity (68.04 to 73.20%) and the specificity (94.17 to 96.12%) of two different HI assays (HI1 and HI2 , with two different IDV antigens) relatively to virus micro-neutralization test (VNT) as reference test. Based on the above characteristics, the true prevalence of IDV was then estimated in Morocco using a stochastic approach. Irrespective of the HI assays used, the estimation of the true prevalence was statistically equivalent (between 48.44% and 48.73%). In addition, the Spearman rank correlation between HI titres and VNT titres was statistically good (0.76 and 0.81 for HA1 and HA2 , respectively). The positive (0.82 and 0.79 for HA1 and HA2 , respectively) and the negative (0.86 and 0.85 for HA1 and HA2 , respectively) agreement indices between results of HI assays and VNT were good and similar. This study allowed for a formal establishment of a positivity cut-off in HI assays for the detection of antibodies directed against IDV. This information is of prime importance to estimate the diagnostic sensitivity and specificity of the test relatively to the VNT (i.e. the reference test). Using these characteristics, the true prevalence of IDV should be determined in a country.

Role of the Hemagglutinin Residue 227 in Immunogenicity of H5 and H7 Subtype Avian Influenza Vaccines in Chickens.

Many H5 and H7 subtype avian influenza vaccines are poorly immunogenic in terms of inducing hemagglutination-inhibition (HI) antibody titers. Residue 227 (H3 numbering) in the receptor binding site in the hemagglutinin (HA) is critical for the detectability of HI antibodies induced by H5 influenza vaccines. However, whether the effect of residue 227 on immunogenicity can be generalized in different subtypes is unclear. In this study, the impact of HA residue 227 on immunogenicity of H5N1, H5N6, and H7N9 avian influenza vaccines was evaluated in chickens. Polymorphism analysis revealed that S227 is overwhelmingly dominant in HA of the H5N1 and H7N9 subtypes, whereas this amino acid is present in a small proportion of H5N6 viruses. The H5N1, H5N6, and H7N9 vaccines harboring S227 in HA induced relatively low HI titers at week 2 postimmunization (pi), and antibody titers increased at week 3 pi. S227N substitution in these vaccines consistently enhanced HI titers significantly. Another H5N6 vaccine harboring Q227 in HA elicited a robust HI antibody response, and Q227S substitution led to a significant drop of HI titers. Cross-HI testing against the wild-type and mutant viruses revealed that the amino acid at position 227 was associated with the detectability of HI titers induced by H5 and H7 avian influenza vaccines. The results indicate an important role of residue 227 in HA in immunogenicity of H5 and H7 subtype avian influenza vaccines in chickens. Our findings also provided useful information for vaccine seed virus selection and genetic engineering for immunogenicity enhancement of avian influenza vaccines.

Serological evidence of avian influenza virus subtype H5 and H9 in live bird market, Myanmar.

Avian Influenza (AI), caused by Alphainfluenzaviruses (AIVs), is a contagious respiratory disease in birds and mammals. AIVs have been reported in poultry worldwide and the impact of AIVs on human health is immense. In this study, a serological survey of AIV subtype H5 and H9 was conducted in a live bird market (LBM) in Yangon, Myanmar during February 2016 to September 2016. A total of 621 serum samples were collected from chickens (n = 489) and ducks (n = 132) from 48 vendors in the LBM. The samples were examined for antibodies against influenza viruses by using NP-ELISA and specific antibodies against AIV-H5N1 (Clade 2.3.4) and AIV-H9N2 (Clade 9.4.2) by using Hemagglutination Inhibition (HI) assay. The result of NP-ELISA assay showed that 12.88 % (80/621) of poultry in LBM was positive for AIV antibodies. In detail, 38.06 % (51/134) of layers, 7.08 % (8/113) of backyard chicken, 2.07 % (5/242) of broilers and 12.12 % (16/132) of ducks were AIV positive. The HI test for specific antibodies against AIV-H5N1 and AIV-H9N2 were 1.77 % (11/621) and 4.51 % (28/621), respectively. Our findings revealed the evidence of AIV-H5N1 and AIV-H9N2 exposure in both chicken and ducks in the LBM in Yangon, Myanmar. Risks of influenza infections and transmission among poultry and humans in the LBMs could not be ignored.

Avian Influenza (H9N2 Subtype) in Iranian Broiler Farms: A Cross-sectional Study.

The present study aimed to determine the seroprevalence of H9N2 influenza in broiler farms at the time of slaughter in Iran. A total of 747 birds were sampled from 74 Farms in 13 provinces within 2013-2016. The obtained sera were investigated using the hemagglutination inhibition (HI) test. Out of 74 sampled farms and 747 birds, 57 farms (77%) and 445 (59.57%) birds were reported to be seropositive. In 2013, 10 farms and 110 birds were sampled out of which three farms (29.6%) and 29 birds (30%) were seropositive. In 2014, 24 farms and 220 birds were sampled out of which 22 farms (91.6%) and 220 birds (86.6%) were positive in six provinces. In 2015, 30 farms and 278 birds were sampled out of which 5 farms (16%) and134 birds (48.2%) were positive in four provinces. Finally, in 2016, 7 farms (70%) out of 10 sampled farms and 62 birds (59%) out of 105 sampled birds were positive for H9N2 in eight provinces. The mean titer of units in 2013 was statistically lower, as compared to that in 2014 (p &lt;0.01). In addition, the proportion of positive serum units in 2013 was statistically lower, as compared to that in 2014 (p &lt;0.001). In general, the prevalence of H9N2 was high indicating the continuous circulation of the virus in Iran. Given the importance and impact of this virus on the poultry industry, people&rsquo;s livelihood, and public health, more epidemiological studies are needed to evaluate the effectiveness of the adopted measures and methods in controlling the H9N2 virus.

Evaluation of an in-house indirect enzyme-linked immunosorbent assay of feline panleukopenia VP2 subunit antigen in comparison to hemagglutination inhibition assay to monitor tiger antibody levels by Bayesian approach.

BACKGROUND: Feline panleukopenia virus (FPV) is an etiologic pathogen of feline panleukopenia that infects all members of Felidae including tigers (Panthera tigris). Vaccinations against FPV among wild felid species have long been practiced in zoos worldwide. However, few studies have assessed the tiger immune response post-vaccination due to the absence of a serological diagnostic tool. To address these limitations, this study aimed to develop an in-house indirect enzyme-linked immunosorbent assay (ELISA) for the monitoring of tiger antibody levels against the feline panleukopenia vaccine by employing the synthesized subunit capsid protein VP2. An in-house horseradish peroxidase (HRP) conjugated rabbit anti-tiger immunoglobulin G (IgG) polyclonal antibody (HRP-anti-tiger IgG) was produced in this study and employed in the assay. It was then compared to a commercial HRP-conjugated goat anti-cat IgG (HRP-anti-cat IgG). Sensitivity and specificity were evaluated using the Bayesian model with preferential conditional dependence between HRP-conjugated antibody-based ELISAs and hemagglutination-inhibition (HI) tests. RESULTS: The posterior estimates for sensitivity and specificity of two indirect ELISA HRP-conjugated antibodies were higher than those of the HI test. The sensitivity and specificity of the indirect ELISA for HRP-anti-tiger IgG and HRP-anti-cat IgG were 86.5, 57.2 and 86.7%, 64.6%, respectively, while the results of the HI test were 79.1 and 54.1%. In applications, 89.6% (198/221) and 89.1% (197/221) of the tiger serum samples were determined to be seropositive by indirect ELISA testing against HRP-anti-tiger and HRP-anti-cat, respectively. CONCLUSION: To the best of our knowledge, the specific serology assays for the detection of the tiger IgG antibody have not yet been established. The HRP-anti-tiger IgG has been produced for the purpose of developing the specific immunoassays for tigers. Remarkably, an in-house indirect ELISA based on VP2 subunit antigen has been successfully developed in this study, providing a potentially valuable serological tool for the effective detection of tiger antibodies.

Immunogenicity and protective efficacy of an EB66® cell culture-derived duck Tembusu virus vaccine.

The avian EB66® cell line, derived from duck embryonic stem cells, has been widely used for producing human and animal therapeutic proteins and vaccines. In current study we evaluated the potential use of EB66® cell line in a cell culture-derived duck Tembusu virus (DTMUV) vaccine development. After optimizing the growth conditions of DTMUV HB strain in EB66® cells, we successfully generated three batches of viruses with ELD50 titres of 105.9/0.1 ml, 105.3/0.1 ml and 105.5/0.1 ml, respectively, for using in the preparation of inactivated vaccines. The immunogenicity and protective efficacy of these EB66® cells-derived inactivated vaccines were examined in ducks. Results indicated that all three batches of vaccines induced haemagglutination-inhibition (HI) antibody response in immunized birds at 2 weeks after a single immunization. Immunized ducks and ducklings were protected against a virulent challenge at 4 weeks after a booster immunization. The duration of immunity was for 3-4 months after a booster immunization. These results demonstrated the feasibility of using EB66® cell line to grow up DTMUV for vaccine preparation. RESEARCH HIGHLIGHTS Duck Tembusu virus can be propagated in EB66® cells. EB66® cell-derived inactivated DTMUV vaccines are immunogenic and can provide protection against a virulent challenge. A long-lasting immunity is induced after a booster immunization.

Serologic investigation of influenza A virus infection in dogs in Poland.

The 2 predominant circulating subtypes of influenza A virus in the dog population, equine-origin H3N8 and avian-origin H3N2, constitute a potential zoonotic risk. We determined the prevalence of influenza A antibodies in 496 dogs in Poland and found 2.21% of sera positive by commercial ELISA. Hemagglutination inhibition (HI) assays indicated 7.25% of sera positive using equine H3N8, swine H3N2, and pandemic H1N1 antigens, with the most frequently detected immune response being to H3N2. Considering interspecies transfer, reassortment ability, and close contact between dogs and humans, infections of dogs with influenza A virus should be monitored.

Triple La Sota re-vaccinations can protect laying chickens for 3 months against drop in egg production caused by velogenic viscerotropic Newcastle disease virus infection.

One hundred and ten Isa Brown layers were vaccinated with La Sota, once at point of lay at 18 weeks and three times at peak of lay which occurred at 27-29 weeks of age. Thereafter, they were weekly monitored for haemagglutination inhibition (HI) antibody decline. The first batch A of the layers were challenged with velogenic viscerotropic Newcastle disease (vvND) virus (vvNDV) on day 24 post-vaccination (PV), when the geometric mean titre (GMT) was 84.4, batch B were challenged on day 48 PV at GMT of 42.2, while batch C were challenged on day 97 PV at GMT of 21.1. The individual chicken HI antibody titres of the 10 layers in batch C at the day of challenge were: 7 layers had HI titres of 16, 2 layers had HI titres of 32 and 1 layer had HI titres of 64. Each challenge in the three batches produced no clinical signs including drop in egg production. But there was initial swelling of the spleen followed by atrophy with high antibody responses. The virus was recovered in all the cloacal swabs on days 3-9 post-challenge (PC) at low titres. On days 145 PV and 48, post-Batch C challenge the remaining hyperimmunized unchallenged layers demonstrated a drop in total % egg production (p < .05) and changes in egg quality. The HI GMT was 256. The virus was recovered in all the cloacal swabs on days 3-9 following appearance of clinical signs. There was no mortality in the experiment. Based on the above observations, it is concluded that triple La Sota re-vaccination can protect layers against a drop in egg production in areas where vvNDV infection is enzootic.

A comparative evaluation of serum biochemistry profile and antigenic relatedness among velogenic and mesogenic Avian avulavirus 1 infection in chickens and pigeons.

Newcastle disease (ND), caused by virulent Avian avulavirus 1 (AAvV 1), affects variety of avian species around the globe. Several AAvV 1 viruses of different genotypes have recently emerged with varying clinical impacts on their susceptible hosts. Although experimental infection with velogenic and mesogenic strains in chickens and pigeons is well-studied, nevertheless, there exists a paucity of data for comparative variations in serum biochemistry profile of susceptible hosts upon challenge with isolates of varying pathogenicities. With this background, a comparative assessment of a range of serum biochemical parameters was made following challenge with duck-originated velogenic strain (sub-genotype VIIi; MF437287) and pigeon-originated mesogenic strain (sub-genotype VIm; KU885949) in chickens and pigeons. For each of the isolate, commercial broiler chickens and wild pigeons were challenged (10-6.51 EID50/0.1 mL for sub-genotype VIIi and 10-6.87 EID50/0.1 mL sub-genotype Vim) separately via intranasal and intraocular route. Sera were collected on 0, 3rd, 5th, 7th, and 9th day post-infection (dpi), and processed for quantitative analysis of different biochemical parameters. By day 3 post-infection (pi), a substantial decrease (p < 0.0001) in serum alkaline phosphatase (ALP) was observed in chickens and pigeons challenged with velogenic isolate. On the other hand, from day 5 pi and onward, a significant increase (p < 0.001) in serum ALP and total protein concentration was observed exclusively in pigeons challenged with mesogenic isolate. For serum aspartate aminotransferase (AST), a significant increase (p < 0.05) in concentration was observed on day 3 pi which decreased from day 5 pi and onward in pigeons and chickens challenged with mesogenic isolate. Also, to reveal antigenic differences among homologous and heterologous vaccine and field-prevalent strains, cross-hemagglutination inhibition assay demonstrated antigenically diverse nature (R-value < 0.5) of both strains from vaccine strain (LaSota, genotype II). The study concludes antigenic differences among prevalent genotypes than vaccine strain and, although requires further studies to ascertain study outcomes, the serum biochemical profile may facilitate presumptive diagnosis of disease in their susceptible hosts.

Continuing evolution of H6N2 influenza a virus in South African chickens and the implications for diagnosis and control.

BACKGROUND: The threat of poultry-origin H6 avian influenza viruses to human health emphasizes the importance of monitoring their evolution. South Africa's H6N2 epidemic in chickens began in 2001 and two co-circulating antigenic sub-lineages of H6N2 could be distinguished from the outset. The true incidence and prevalence of H6N2 in the country has been difficult to determine, partly due to the continued use of an inactivated whole virus H6N2 vaccine and the inability to distinguish vaccinated from non-vaccinated birds on serology tests. In the present study, the complete genomes of 12 H6N2 viruses isolated from various farming systems between September 2015 and February 2019 in three major chicken-producing regions were analysed and a serological experiment was used to demonstrate the effects of antigenic mismatch in diagnostic tests. RESULTS: Genetic drift in H6N2 continued and antigenic diversity in sub-lineage I is increasing; no sub-lineage II viruses were detected. Reassortment patterns indicated epidemiological connections between provinces as well as different farming systems, but there was no reassortment with wild bird or ostrich influenza viruses. The sequence mismatch between the official antigens used for routine hemagglutination inhibition (HI) testing and circulating field strains has increased steadily, and we demonstrated that H6N2 field infections are likely to be missed. More concerning, sub-lineage I H6N2 viruses acquired three of the nine HA mutations associated with human receptor-binding preference (A13S, V187D and A193N) since 2002. Most sub-lineage I viruses isolated since 2015 acquired the K702R mutation in PB2 associated with the ability to infect humans, whereas prior to 2015 most viruses in sub-lineages I and II contained the avian lysine marker. All strains had an unusual HA0 motif of PQVETRGIF or PQVGTRGIF. CONCLUSIONS: The H6N2 viruses in South African chickens are mutating and reassorting amongst themselves but have remained a genetically pure lineage since they emerged more than 18 years ago. Greater efforts must be made by government and industry in the continuous isolation and characterization of field strains for use as HI antigens, new vaccine seed strains and to monitor the zoonotic threat of H6N2 viruses.

Ecuadorian mainland industrial poultry production is free of H5/H7 Avian influenza virus: National surveillance program in 2016.

Avian influenza (AI) is a disease caused by influenza viruses type A that belong to the Orthomyxoviridae family. AI induces high economic losses in poultry production worldwide. Due to a possible outbreak, a national surveillance program was needed. From April to July 2016, 152 industrial poultry farms were randomly sampled. All samples were analyzed by competitive ELISA for Influenza type A viruses. Suspicious and positive sera were further analyzed by Hemagglutination Inhibition (HI) in order to serotype H5 or H7 low pathogenic avian influenza virus (LPAIV). The farms sampled showed 94.08%, 3.95% and 1.97% of negative, positive and suspicious results, respectively. However, serotyping revealed all positive and suspicious samples were negative to H5/H7 LPAIV. Our results show the absence of AI in the mainland Ecuadorian industrial poultry production.

A(H9N2) influenza viruses associated with chicken mortality in outbreaks in Algeria 2017.

In late 2017, increased mortality was detected in chicken farms in Algeria undergoing A(H9N2) influenza outbreaks. Analysis of viruses isolated from affected farms showed that they were monophyletic, were of the G1 hemagglutinin (HA) lineage, and were antigenically and genetically similar to viruses detected contemporaneously in other countries in Northern Africa and the Middle East. The virus was able to spread via contact transmission between ferrets but did not cause disease in intravenously inoculated chickens.

Serological evidence of influenza virus infection in captive wild felids, Thailand.

Influenza virus is known to affect wild felids. To explore the prevalence of influenza viruses in these animal species, 196 archival sera from 5 felid species including Panthera tigris (N=147), Prionailurus viverrinus (N=35), Panthera leo (N=5), Pardofelis temminckii (N=8) and Neofelis nebulosa (N=1) collected between 2011 and 2015 in 10 provinces of Thailand were determined for the presence of antibody to avian and human influenza viruses. Blocking enzyme-linked immunosorbent (ELISA) assay and hemagglutination inhibition (HI) assay were employed as the screening tests, which the serum samples with HI antibody titers ≥20 were further confirmed by cytopathic effect/hemagglutination based-microneutralization (CPE/HA-based microNT) test. Based on HI and microNT assays, the seropositive rates of low pathogenic avian influenza (LPAI) H5 virus, highly pathogenic avian influenza (HPAI) H5 virus and human H1 virus were 1.53% (3/196), 2.04% (4/196) and 6.63% (13/196), respectively. In addition, we also found antibody against both LPAI H5 virus and HPAI H5 virus in 2 out of 196 tested sera (1.02%). Evidences of influenza virus infection were found in captive P. tigris in Kanchanaburi, Nakhon Sawan and Ratchaburi provinces of Thailand. The findings of our study highlights the need of a continuous active surveillance program of influenza viruses in wild felid species.