Intravenous Pathogenicity Index Test Research Articles

Isolation and Biological Characterization of Newcastle Disease Virus (NDV) Field Isolate Pigeon (Columba livia) from Live Bird Market, East Java in 2019

Background: Avian Paramyxovirus (APMV) type-1 is the leading cause of Newcastle Disease (ND) and taxonomically belongs to the family Paramyxoviridae, genus Avulavirus. Due to its high transmission rate, Newcastle Disease (ND) is included in the A list by the OIE. Purpose: To determine the biological characterize the Newcastle Disease Virus (NDV) field isolate of pigeons (Columba livia) using Mean Death Time (MDT), Intracerebral Pathogenicity Index (ICPI), and Intravenous Pathogenicity Index (IVPI). Methods: Twenty pigeon organ samples were obtained from bird markets in East Java, and one was used as a positive control (LaSota). Organs were isolated from embryonated chicken eggs, identified by the HA test, and then confirmed by the HI test. Furthermore, positive samples were tested for MDT with a 10-1-10-18 dilution (0.1 ml and observed for eight days. The ICPI test used a fresh NDV suspension (0.05 ml and was observed for eight days. The IVPI test used a dose of 0.1 ml and was observed for ten days. Result: The MDT values of isolates MB1/NDV/19, MB2/NDV/19, MB3/NDV/19, and MG1/NDV/19 were 91.2 hours, 112.8 hours, 110.4 hours, and 124,8 hours. The ICPI values of isolate MB1/NDV/19 was 0.2375, MB2/NDV/19 was 0.375, MB3/NDV/19 was 0.5375, and MG1/NDV/19 was 0.3. The IVPI value of isolate MB1/NDV/19 was 0, MB2/NDV/19 was 0, MB3/NDV/19 was 0, and MG1/NDV/19 was 0. Conclusion: All four field samples were positive for NDV as a lentogenic strain based on the MDT, ICPI, and IVPI tests.

Tissue tropism and pathology of highly pathogenic avian influenza H5N6 virus in chickens and Pekin ducks

The highly pathogenic avian influenza (HPAI) H5N6 virus caused outbreaks on commercial poultry farms in the Netherlands in 2017–2018, holding chickens and Pekin ducks. Intravenous pathogenicity index (IVPI) tests confirmed the high pathogenicity of the virus. Tissues derived from birds from infected farms (natural infection) and IVPI tests (experimental infection) were used to compare histopathology and virus distribution in both poultry species. After natural infection in chickens, histopathologic changes were present in the respiratory tract and several internal organs in both chickens and Pekin ducks. Viral antigen expression in the tissues of chickens varied from that in ducks. Virus expression was found in epithelial, mononuclear and endothelial cells in chickens. In contrast to the major role infected endothelial cells seem to play in systemic infections of chickens, in ducks the number of infected endothelial cells was very limited. Therefore, endothelial cell infection likely does not play a major role in systemic infection and disease progression in HPAI H5N6 virus infected Pekin ducks.

Assessment of experimental pathogenicity of avian influenza virus H9N2 isolates by intravenous pathogenicity index (IVPI) test and histopathology

A total of 1,423 number of tissue samples received from various parts of India were processed for virus isolation in chicken embryos of 9-11 d old as a part of programme to monitor Avian Influenza Virus (AIV) infection in Indian poultry population and a total number of three samples were positive by HA test and the titre of the virus isolates ranged from 1:8 to 1:64. The virus isolates had been subjected to HI test with the reference positive serum imported from NVSL, USA for various subtypes. The virus isolates gave a HI titre of 1:32 with H9 subtype specific reference positive serum indicating that the virus isolates were influenza A H9 subtype. One of the isolates (accession no. 3722/04) was subjected to neuraminidase assay and the virus was found by N2 subtype and also virus sub typing was done by RT-PCR for further confirmation. The influenza H9N2 virus isolates (accession no. 2543/04, 2544/04, 2317/04, 2424/04, and 3722/04) were used in the intravenous pathogenicity index test. In the present study no, clinical signs and/or gross lesions in experimentally inoculated chickens were observed. All the five isolates studied were found to be non-pathogenic according to the European Union definition. The organs collected from the experimental chickens did not show significant lesions, on histopathological examination, except for some minor changes in some of the organs. Immunofluorescence test was used to study the tissue tropism of avian influenza viruses’ isolates experimentally infected in chickens. The antigen was detected only in the brain and trachea of the chickens experimentally infected with the isolates having accession no. 2543/04 and intestine of chickens experimentally infected with the isolate having accession number 2544/04. Avian influenza virus re-isolation from experimentally infected chickens was attempted in 9-11 d old embryonated chicken eggs. Virus could be re-isolated from some organs, three groups infected with the isolates with accession numbers 2543/04, 2544/04 and 2317/04. Thus, the present work was envisaged to fill in the gap formed by this lack of information on avian influenza in India.

Genetic and biological characteristics of avian influenza virus subtype H1N8 in environments related to live poultry markets in China

BackgroundSince 2008, avian influenza surveillance in poultry-related environments has been conducted annually in China. Samples have been collected from environments including live poultry markets, wild bird habitats, slaughterhouses, and poultry farms. Multiple subtypes of avian influenza virus have been identified based on environmental surveillance, and an H1N8 virus was isolated from the drinking water of a live poultry market.MethodsVirus isolation was performed by inoculating influenza A-positive specimens into embryonated chicken eggs. Next-generation sequencing was used for whole-genome sequencing. A solid-phase binding assay was performed to test the virus receptor binding specificity. Trypsin dependence plaque formation assays and intravenous pathogenicity index tests were used to evaluate virus pathogenicity in vitro and in vivo, respectively. Different cell lines were chosen for comparison of virus replication capacity.ResultsAccording to the phylogenetic trees, the whole gene segments of the virus named A/Environment/Fujian/85144/2014(H1N8) were of Eurasian lineage. The HA, NA, PB1, and M genes showed the highest homology with those of H1N8 or H1N2 subtype viruses isolated from local domestic ducks, while the PB2, PA, NP and NS genes showed high similarity with the genes of H7N9 viruses detected in 2017 and 2018 in the same province. This virus presented an avian receptor binding preference. The plaque formation assay showed that it was a trypsin-dependent virus. The intravenous pathogenicity index (IVPI) in chickens was 0.02. The growth kinetics of the A/Environment/Fujian/85144/2014(H1N8) virus in different cell lines were similar to those of a human-origin virus, A/Brisbane/59/2007(H1N1), but lower than those of the control avian-origin and swine-origin viruses.ConclusionsThe H1N8 virus was identified in avian influenza-related environments in China for the first time and may have served as a gene carrier involved in the evolution of the H7N9 virus in poultry. This work further emphasizes the importance of avian influenza virus surveillance, especially in live poultry markets (LPMs). Active surveillance of avian influenza in LPMs is a major pillar supporting avian influenza control and response.

Detection of reassortant avian influenza A (H11N9) virus in environmental samples from live poultry markets in China.

BackgroundAvian influenza viruses have caused human infection and posed the pandemic potential. Live poultry markets are considered as a source of human infection with avian influenza viruses. Avian influenza routine surveillance of live poultry markets is taken annually in China. We isolated the 2 H11N9 influenza virus from the surveillance program. To better understand the risk caused by these new viruses, we characterize the genetic and pathogenicity of the two viruses.MethodsViral isolation was conducted with specific pathogen-free (SPF) embryonated chicken eggs. Whole genome was sequenced, and phylogenetic analysis was conducted.ResultsTwo H11N9 viruses were identified, with all 8 segments belonging to the Eurasian lineage. The HA, NA, M, NS and PA genes were similar to virus isolates from ducks, and the NP, PB2 and PB1 gene segments were most similar to those viruses from wild birds, indicating that the H11N9 viruses might represent reassortant viruses from poultry and wild birds. The HA receptor binding preference was avian-like, and the cleavage site sequence of HA showed low pathogenic. The NA gene showed 94.6 % identity with the novel H7N9 virus that emerged in 2013. There was no drug resistance mutation in the M2 protein. The Asn30Asp and Thr215Ala substitutions in the M1 protein implied a potentially increased pathogenicity in mice. Both viruses were low-pathogenic strains, as assessed by the standards of intravenous pathogenicity index (IVPI) tests.ConclusionTwo reassortant H11N9 avian influenza viruses were detected. These viruses showed low pathogenicity to chickens in the IVPI test. Public health concern caused by the reassortant H11N9 viruses should be emphasized during the future surveillance.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0149-2) contains supplementary material, which is available to authorized users.

Avian Influenza Monitoring in Migrating Birds in Taiwan During 1998–2007

Avian influenza virus (AIV) monitoring in migratory birds has been performed in Taiwan since 1998. From 1998 to 2007, 29,287 samples were collected from wild ducks, shorebirds, and other wild birds in the four wetlands around Taiwan and at two outside islets, Penghu and Kinmen. Virus isolation was performed for all collected samples by inoculating chicken embryos. The AIV in the allantoic fluid was identified using hemagglutination and reverse transcription PCR. The AIV prevalence from those samples was 0.81% (237/29,287). The peak prevalence reached 1.06% (186/17,493) from September to December, during which time migrating ducks came from the North. The prevalence from January to April was 0.51%. However, no virus was isolated from May to August. The partial HA genes of 28 H4 AIVs were sequenced and analyzed. The phylogenetic tree showed that a correlation existed between the isolation years and the evolutional distances. The pathogenicity of the isolated H5 and H7 AIVs was determined by intravenous pathogenicity index (IVPI) testing in specific-pathogen-free chickens and by HA cleavage sequencing. Using the IVPI test and the HA cleavage sequences, all of the H5 or H7 AIVs isolated were determined to be low pathogenicity AIVs.

Characterization of duck H5N1 influenza viruses with differing pathogenicity in mallard (Anas platyrhynchos) ducks

A number of H5N1 influenza outbreaks have occurred in aquatic birds in Asia. As aquatic birds are the natural reservoir of influenza A viruses and do not usually show clinical disease upon infection, the repeated H5N1 outbreaks have highlighted the importance of continuous surveillance on H5N1 viruses in aquatic birds. In the present study we characterized the biological properties of four H5N1 avian influenza viruses, which had been isolated from ducks, in different animal models. In specific pathogen free (SPF) chickens, all four isolates were highly pathogenic. In SPF mice, the S and Y isolates were moderately pathogenic. However, in mallard ducks, two isolates had low pathogenicity, while the other two were highly pathogenic and caused lethal infection. A representative isolate with high pathogenicity in ducks caused systemic infection and replicated effectively in all 10 organs tested in challenged ducks, whereas a representative isolate with low pathogenicity in ducks was only detected in some organs in a few challenged ducks. Comparison of complete genomic sequences from the four isolates showed that the same amino acid residues that have been reported to be associated with virulence and host adaption/restriction of influenza viruses were present in the PB2, HA, NA, M and NS genes, while the amino acid residues at the HA cleavage site were diverse. From these results it appeared that the virulence of H5N1 avian influenza viruses was increased for ducks and that amino acid substitutions at the HA cleavage site might have contributed to the differing pathogenicity of these isolates in mallards. A procedure for the intravenous pathogenicity index test in a mallard model for assessing the virulence of H5/H7 subtype avian influenza viruses in waterfowl is described.

Assessment of Pathogenic Potential of Two Indian H5N1 Highly Pathogenic Avian Influenza Virus Isolates by Intravenous Pathogenicity Index Test

Intravenous Pathogenicity Index (IVPI) test was conducted to assess the pathogenicity of two H5N1 (A/Ck/Ind/7966/06 and A/Ck/Ind/7972/06) AIV isolates. Both the H5N1 virus isolates were isolated from natural outbreaks during 2006, both isolates caused death of all birds with in 48 h after inoculation experimentally, birds showed typical clinical signs, gross and microscopic lesions of Avian influenza. IVPI of A/Ck/Ind/7966/06 and A/Ck/Ind/7972/06 was 2.96 and 2.95 respectively. This test showed that both H5N1 isolates are highly pathogenic. Virus could be re-isolated from all the organs of infected chickens and it was reconfirmed by RT-PCR using WHO and Lee primers.

Assessing Potential Pathogenicity of Avian Influenza Virus: Current and Experimental System

An avian influenza (AI) isolate can be classified as a high pathogenicity avian influenza (HPAI) virus based upon the results of the standard intravenous pathogenicity index test; molecular classification, which is derived by sequencing the hemagglutinin gene across the site coding for the cleavage site; or a combination. However, discordant results between the molecular classification and virulence for experimentally infected chickens have been observed with several H5 and H7 subtype AI viruses. Because the declaration of HPAI virus results in severe effects on trade for the entire country, the gap between the genetic and phenotypic markers is an important issue, and it requires us to reexamine what should be considered an HPAI virus by the Office International des Epizooties standards. To better understand and assess the true virulence of the virus, potential pathogenicity of H5 and H7 subtype AI virus isolates has been assessed by examining the plaquing efficiency of the virus in chicken embryo fibroblast cells, conducting 14-day-old embryo passage and selection system, and applying in vitro mutagenesis coupled with reverse genetics. The potential value of these complimentary methods in assessing potential pathogenicity of the AI virus is discussed.

H5N1 Influenza Virus, Domestic Birds, Western Siberia, Russia

To the Editor: Highly pathogenic H5N1 avian influenza virus caused disease outbreaks in poultry and wild birds in several Asian, European, and African countries from 2003 to 2006. This virus caused >90 human deaths in Vietnam, Thailand, People's Republic of China, Indonesia, Turkey, Iraq, and Cambodia (1–3). Hemagglutinin (HA) and neuraminidase (NA) genes of this virus were derived from the Gs/Gd/1/96-like lineage, and 6 genes that encode internal viral proteins were derived from other lineages (1). Highly pathogenic H5N1 virus genetically related to the A/Chicken/Shantou/4231/03 (People's Republic of China) isolate caused disease outbreaks in poultry in Japan from the end of December 2003 to March 2004 (4). In May and June 2005, highly pathogenic H5N1 virus was isolated from migratory birds during disease outbreaks near Lake Qinghai in western People's Republic of China. HA, NA, and nucleoprotein genes of the Qinghai virus were closely related to H5N1 virus A/Chicken/Shantou/4231/03 isolated in People's Republic of China in 2003. Five other viral genes (matrix, PA, PB1, PB2, and nonstructural protein) were closely related to an H5N1 Hong Kong Special Administrative Region, People's Republic of China 2004 isolate (A/Peregrin falcon/HK/D0028/04) and H5N1 virus A/Chicken/Shantou/810/05 isolated in People's Republic of China in 2005 (5,6). In July 2005, domestic poultry began to die in the village of Suzdalka in western Siberia, Russia (Dovolnoe County, Novosibirsk region). Autopsies showed serious alterations in all internal organs tested. Approximately 95%–100% of the lungs were affected, and all serous membranes showed petechial and confluent hemorrhages. The highest concentration of hemorrhages was in the pericardium. Organs from 3 birds (1 turkey and 2 chickens) that had died during this outbreak were further analyzed. Homogenates of lungs, kidneys, and spleens were tested by hemagglutination inhibition (HI) assay. The highest titers, 32 and 16, were observed in the spleen of the turkey and kidneys of the chickens, respectively. H5 influenza A virus was identified in a homogenate of turkey spleen by conventional HI assay (7) with a panel of reference antisera. For the identification of NA subtype, RNA was isolated from turkey spleen homogenate and synthesis of viral cDNA was performed as previously described (7). Amplification by polymerase chain reaction (PCR) and sequencing of an NA gene fragment were performed with in-house primers (sequences of primers are available on request). The nucleotide sequence obtained (547 bp, GenBank accession no. {type:entrez-nucleotide,attrs:{text:DQ231243,term_id:78146121,term_text:DQ231243}}DQ231243) showed 100% identity with the NA gene of H5N1 viruses isolated in People's Republic of China in 2005 (e.g., A/Great black-headed gull/Qinghai/1/05) (5,6). Homogenates of bird organs (turkey spleen and chicken kidneys) were injected into the allantoic cavity of 10-day-old embryonated chicken eggs. Three hemagglutinating agents were isolated (titers 1,024–2,048) and identified as H5 influenza A virus (A/Turkey/Suzdalka/Nov-1/05, A/Chicken/Suzdalka/Nov-11/05, and A/Chicken/Suzdalka/Nov-12/05) by reverse transcription–PCR and sequencing (isolation of RNA from allantoic fluid and synthesis of virus cDNA were performed as previously described [7]). PCR amplification and sequencing of a fragment of the HA gene were performed with an in-house primer set for the H5 gene (available on request). Phylogenetic analysis of nucleotide sequences obtained (GenBank accession nos. {type:entrez-nucleotide,attrs:{text:DQ231242,term_id:78146106,term_text:DQ231242}}DQ231242, {type:entrez-nucleotide,attrs:{text:DQ231241,term_id:78146083,term_text:DQ231241}}DQ231241, and {type:entrez-nucleotide,attrs:{text:DQ231240,term_id:78146041,term_text:DQ231240}}DQ231240) indicated that western Siberian 2005 isolates belong to the Gs/Gd/1/96-like lineage and form a cluster with H5N1 viruses isolated from migratory birds in the People's Republic of China in 2005 (5), from poultry in Japan in 2004 (4), and from poultry and humans in Asian countries in 2003 and 2004 (1) (Figure). Deduced amino acid HA cleavage site sequences of all isolates (PQGERRRKKR/GL) corresponded to highly pathogenic Asian H5N1 influenza virus variants (5,6). Figure Phylogenetic tree of H5 hemagglutinin genes of influenza A viruses. The 3 H5 western Siberian 2005 viruses isolated in this study are shaded. Phylogenetic analysis was performed by the neighbor-joining method with the Molecular Evolutionary Genetic Analysis ... To test virulence, 10 six-week-old chickens were intravenously infected with isolate A/Turkey/Suzdalka/Nov-1/05 as previously described (7). All viruses isolated were highly pathogenic (all chickens died within a day of infection). We isolated H5N1 influenza virus from the spleen of a turkey that died during an outbreak in poultry in western Siberia in July 2005. HA and NA genes of this virus were closely related to those of H5N1 avian influenza viruses that caused outbreaks in birds in Asian countries from 2003 to 2005 and in Japan in 2003 and 2004. The corresponding isolate, A/Turkey/Suzdalka/Nov-1/05, from turkey spleen was highly pathogenic for chickens in the laboratory intravenous pathogenicity index test. The origin of this H5N1 virus in western Siberia is not known. Migratory birds could have introduced this virus because western Siberia is located on a flyway of wild birds that migrate in the spring from southeastern Asia. Highly pathogenic Asian H5N1 influenza virus in western Siberia demonstrates spread of these Asian viruses into new areas and suggests a larger geographic distribution.

Isolation and characterization of virus of highly pathogenic avian influenza H5 subtype of chicken from outbreaks in Indonesia

A study on the isolation and characterization of Highly Pathogenic Avian Influenza of chicken from outbreaks in Indonesia was conducted at Indonesian Research Institute for Veterinary Science. Outbreaks of avian disease had been reported in Indonesia since August 2003 affecting commercial layer, broiler, quail, and ostrich and also native chicken with showing clinical signs such as cyanosis of wattle and comb, nasal discharges and hypersalivation, subcutaneous ptechiae on foot and leg, diarre and sudden high mortality. The aim of this study is to isolate and characterize the causal agent of the disease. Samples of serum, feather follicle, tracheal swab, as well as organs of proventriculus, intestine, caecal tonsil , trachea and lungs were collected from infected animals. Serum samples were tested haemaglutination/haemaglutination inhibition to Newcastle Disease and Egg Drop Syndrome viruses. Isolation of virus of the causal agent of the outbreak was conducted from samples of feather follicle, tracheal swab, and organs using 11 days old specific pathogen free (SPF) embryonated eggs. The isolated viruses were then characterised by agar gel precipitation test using swine influenza reference antisera, by haemaglutination inhibition using H1 to H15 reference antisera, and by electron microscope examination. The pathogenicity of the viruses was confirmed by intravenous pathogenicity index test and its culture in Chicken Embryo Fibroblast primary cell culture without addition of trypsin. The study revealed that the causative agent of the outbreaks of avian disease in Indonesia was avian influenza H5 subtype virus based upon serological tests, virus isolation and characterization using swine influenza reference antisera, and electron microscope examination. While subtyping of the viruses using H1 to H15 reference antisera suggested that the virus is very likely to be an avian influenza H5N1 subtype virus. The pathogenicity test confirmed that the viruses are highly pathogenic to experimental animals. It is concluded that the causative agent of the outbreaks of avian disease in Indonesia was avian influenza H5 subtype virus. The result has been the basis of further study such as development serological tests and vaccine production. The decission of Indonesian Government to conduct vaccination program using homolog vaccine in order to control the disease is regarded as the correct choice. However, it should be accompanied by conducting surveillance and monitoring of the disease as well as the possibility of mutation of virus. The program should be coordinated nationally. Key words: Virus isolation, characterization, chicken, outbreak, highly pathogenic avian influenza (HPAI), H5 subtype, Indonesia

Role of fusion protein cleavage site in the virulence of Newcastle disease virus

Newcastle disease virus (NDV) causes a highly contagious and economically important disease in poultry. Viral determinants of NDV virulence are not completely understood. The amino acid sequence at the protease cleavage site of the fusion (F) protein has been postulated as a major determinant of NDV virulence. In this study, we have examined the role of F protein cleavage site sequence in NDV virulence using reverse genetics technology. The sequence G-R-Q-G-R present at the cleavage site of the F protein of avirulent strain LaSota was mutated to R-R-Q-K-R, which is present in the F cleavage site of neurovirulent strain Beaudette C (BC). The resultant mutated LaSota V.F. virus did not require exogenous protease for infectivity in cell culture, indicating that the F protein was cleaved by intracellular proteases. The virulence of the mutant and parental viruses was evaluated in vivo by intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index (IVPI) tests in chickens. Our results showed that the modification of the F protein cleavage site resulted in a dramatic increase in virulence from an ICPI value of 0.00 for LaSota to a value of 1.12 for LaSota V.F. However, the ICPI value of LaSota V.F. was lower than that of BC, which had a value of 1.58. Interestingly, the IVPI tests showed values of 0.00 for both LaSota and LaSota V.F. viruses, compared to the IVPI value of 1.45 of BC. In vitro characteristics of the viruses were also studied. Our results demonstrate that the efficiency of cleavage of the F protein plays an important role if the NDV is delivered directly into the brains of chicks, but there could be other viral factors that probably affect peripheral replication, viremia, or entry into the central nervous system.

Virulence of Pigeon-Origin Newcastle Disease Virus Isolates for Domestic Chickens

The virulence of six pigeon-origin isolates of Newcastle disease virus (NDV) was evaluated before and after passage in white leghorn chickens. Four isolates were defined as pigeon paramyxovirus-1 (PPMV-1) and two isolates were classified as avian paramyxovirus-1 (APMV-1) with NDV monoclonal antibodies. The four PPMV-1 isolates were passaged four times in chickens, and the APMV-1 isolates were passaged only once. Infected birds were monitored clinically and euthanatized. Tissues were collected for histopathology, in situ hybridization with a NDV matrix gene digoxigenin-labeled riboprobe, and immunohistochemistry with an anti-peptide antibody to the nucleoprotein. Mean death time, intracerebral pathogenicity index, and intravenous pathogenicity index tests performed before and after passage in chickens demonstrated increased virulence of the passaged PPMV-1 isolates and high virulence of the original isolates of APMV-1. Sequence analysis of the fusion protein cleavage site of all six isolates demonstrated a sequence typical of the virulent pathotype. Although the pathotyping results indicated a virulence increase of all passaged PPMV-1 isolates, clinical disease was limited to depression and some nervous signs in only some of the 4-wk-old specific-pathogen-free white leghorns inoculated intraconjunctivally. However, an increased frequency of clinical signs and some mortality occurred in 2 wk olds inoculated intraconjunctivally with passaged virus. Histologically, prominent lesions in heart and brain were observed in birds among all four groups inoculated with the PPMV-1 isolates. The behavior of the two pigeon-origin APMV-1 isolates when inoculated into chickens was characteristic of velogenic viscerotropic NDVs and included necro-hemorrhagic lesions in the gastrointestinal tract.

Characterization of Newcastle disease viruses isolated from chickens and pigeons in the South Marmara region of Turkey

Summary Between December 1992 and April 1993, Newcastle disease (ND) outbreaks occurred in a broiler flock, a layer flock, in village chickens of two prefectures and in five pigeon lofts in the South Marmara Region of Turkey. Four viruses from chickens and five from pigeons were isolated from these outbreaks, and identified as Newcastle disease viruses (NDV). All were characterized as velogenic strains based on their mean death time in eggs, ability to form plaques in tissue culture and, for some isolates, intracerebral pathogenicity index and intravenous pathogenicity index tests. Monoclonal antibody typing showed that eight of the nine isolates were indistinguishable from each other.

Avian paramyxovirus serotype 1 (Newcastle disease virus)--infections in falcons.

From eight falcons and one pigeon which died from NDV over a period of 15 months in Dubai, United Arab Emirates, PMV-1 viruses were isolated on quail embryo cell cultures. The identification of all 9 strains were achieved with the haemagglutination inhibition test against polyclonal chicken PMV-1 antiserum, against mouse monoclonal antibodies as well as with the immunoperoxidase test. Intracerebral pathogenicity index and intravenous pathogenicity index tests were also carried out. Although the virus isolates in this study fell into two distinct groups, the overall clinical symptoms displayed by the falcons tailed to demonstrate any trends or specificity unique to a group. The isolate obtained from a pigeon was similar to the isolates from one group of the falcons and showed no identity with the pigeon variant virus.

Assessing Pathogenicity Potential of Waterfowl-Origin Type A Influenza Viruses in Chickens

Intravenous pathogenicity index (IVPI) tests on 29 wild duck-origin type A influenza viruses, two turkey-origin type A influenza viruses, and one chicken-origin type A influenza virus resulted in indices ranging from 0.0 to 0.49. Most of the wild duck-origin viruses and the two turkey-origin viruses had indices of 0.0, indicating they are not pathogenic. Six of the duck-origin viruses had indices ranging from 0.25 to 0.49, and the IVPI for A/chicken/Alabama/75 (H4N8) was 0.49, indicating they had low pathogenic potential. An IVPI of 1.25 up to the maximum score of 3.0 is necessary for a type A influenza virus to be classified as highly pathogenic. Gross lesions observed in chickens dying following intravenous viral challenge included kidney swelling with more prominent lobular patterns, but visceral urate deposits were not present. The usefulness of the IVPI test in evaluating the pathogenicity potential of nonpathogenic and low-pathogenic strains of avian influenza virus may be limited.

A two year survey on the control of the importation of captive birds into Great Britain.

The operation of the Importation of Captive Birds Order 1976 is described. In the first 24 months that the order was effective, a total of 183,189 birds were landed. Of these 5829 (3.18 per cent) were dead on arrival, 8643 (4.71 per cent) died in quarantine and 474 batches of carcases were submitted for post mortem examination. Chlamydia infections were diagnosed in birds from 14 quarantine/isolation lots and salmonellae were isolated from 23 lots. Thirty-six haemagglutinating agents were isolated from 17 quarantine/isolation lots. These were identified as eight influenza A viruses with Hav 7 Neq 2 subtypes (associated with two importations); 14 influenza A viruses with Hav 4 Nav 1 subtypes (six importations); four yucaipa-like paramyxoviruses (three importations); four 449-like paramyxoviruses (two importations); one unspecified paramyxovirus; five Newcastle disease viruses (NDV) (two importations). Four of the NDV isolates, associated with one importation, were shown to be velogenic viruses by intravenous pathogenicity index tests in six-week-old chickens.