Characterization of two low pathogenic avian influenza viruses isolated in Hungary in 2007.

Two low pathogenic (LP) avian influenza virus strains, A/mallard/Hungary/19616/07 (H3N8) and A/mute swan/Hungary/5973/07 (H7N7), isolated as part of the National Surveillance Program in Hungary, were fully sequenced and characterized. The two viruses showed the closest phylogenetic relationship regarding their acidic polymerase genes. The H7N7 Hungarian virus and some H5N2 influenza viruses isolated from Korean pigs appeared to have their basic polymerase gene 1 from a relatively recent common ancestor.

Isolation and characterization of avian paramyxovirus type 1 (Newcastle disease) viruses from a flock of ostriches (Struthio camelus) and emus (Dromaius novaehollandiae) in Europe with inconsistent serology.

During a 95-day study period in 1995 in Denmark, 18 ostriches in a flock of 77 ostriches and four emus held in quarantine died. Clinical and pathological observations did not indicate the presence of transmissible infectious disease in the flock. Management failures and indoor housing were believed to have contributed significantly to the number of deaths.

Third genome size category of avian paramyxovirus serotype 1 (Newcastle disease virus) and evolutionary implications.

The goal of the study was to establish if there was a relationship between molecular patterns and virus evolution. Therefore the complete genome sequence of two distinct apathogenic Newcastle disease virus (NDV) strains was determined and a third genome size category, containing 15,198 nucleotides, was recognized. Phylogenetic analysis revealed that two major separations resulting in three genome size categories occurred during the history of NDV.

Thrombocytopenia in Newcastle disease: haematological evaluation and histological study of bone marrow.

A Newcastle disease virus (NDV) isolated in Mexico and called Chimalhuacan strain was characterised by gene F restriction enzyme analysis and found to be a genotype II velogenic virus. Haematological evaluations and histological studies of bone marrow were conducted on chickens experimentally infected with the Chimalhuacan virus and on control chickens. Within 72 hours post infection (hpi), a 50% decrease in thrombocyte and monocyte counts and a complete cellular depletion in bone marrow islands were evident in the infected group.

Lentogenic field isolates of Newcastle disease virus isolated in Canada and Hungary are identical with the vaccine type used in the region.

Lentogenic field isolates of Newcastle disease virus were examined by restriction enzyme analysis of RT-PCR products generated from the matrix protein gene that discriminates between strains LaSota and B-1, the two most widely used lentogenic vaccine viruses. Isolates were derived from regions where, exclusively or predominantly, only one type of vaccine was employed. Viruses collected in Hungary for two decades were exclusively of LaSota-type while the Canadian collection predominantly included B-1, which corresponded to the vaccine types used in the regions.

Identification and subgrouping of pigeon type Newcastle disease virus strains by restriction enzyme cleavage site analysis.

A host variant of Newcastle disease virus (NDV, genus Avulavirus, family Paramyxoviridae) is responsible for an autonomous disease in pigeons. It emerged in the late 1970s in the Mediterranean region. Despite great genetic diversity the vast majority of strains belong to a monophyletic group (sublineage VIb) within genotype VI of NDV strains that were indigenous in the region at that time.

Retrospective characterization of Newcastle Disease Virus Antrim '73 in relation to other epidemics, past and present.

In November 1973 Newcastle disease suddenly appeared in Northern Ireland, where the viscerotropic disease had not been seen in 3 1/2 years and the two Irelands had been regarded as largely disease free for 30 years. It was successfully controlled with only 36 confirmed affected layer flocks, plus 10 more slaughtered as 'dangerous contacts'. Contemporary investigations failed to reveal the source of the Irish epidemic.

Antigenic and genetic diversity of early European isolates of Infectious bursal disease virus prior to the emergence of the very virulent viruses: early European epidemiology of Infectious bursal disease virus revisited?

Eleven Polish and Hungarian isolates of Infectious bursal disease virus (IBDVs) obtained in the 70/80s (early IBDV) and in the 90s (recent IBDV) were characterized in an Antigen-Capture-ELISA with a panel of neutralizing monoclonal antibodies (Mabs), and by nucleotide sequencing of the VP2 variable domain (vVP2). The viruses were compared with reference IBDV strains, among others with Faragher 52/70 (F52/70, classical, isolated 1970), 89163 (typical very virulent-vvIBDV, isolated 1989) and 91168 (antigenically modified vvIBDV, isolated 1991). Only one of the early isolates (Hungarian strain P1) proved antigenically and genetically similar to F52/70.

Positive identification of Newcastle disease virus vaccine strains and detection of contamination in vaccine batches by restriction site analysis of the matrix protein gene.

Twelve vaccine batches prepared from avirulent vaccine strains of Newcastle disease virus produced by seven manufacturers were identified by analysis of the matrix (M) protein gene with restriction enzymes MboI and HinfI. The analyses have revealed the presence of the strain indicated by the manufacturers (namely B-1, LaSota or Ulster 2C), except in one case when the vaccine contained strain V4 Queensland instead of VGGA as indicated. In addition, several batches of both monovalent and combined vaccines containing strain LaSota of the same company consistently disclosed contamination with strain B-1.

Phylogenetic analysis reveals extensive evolution of avian paramyxovirus type 1 strains of pigeons (Columba livia) and suggests multiple species transmission.

Partial sequence and residue substitution analyses of the fusion protein gene were performed for 68 strains of avian paramyxovirus type 1 of pigeons (PPMV-1), an antigenic variant of Newcastle disease virus (NDV) of chickens, derived from 16 countries between 1978 and 2002. The majority of isolates clustered into a single genetic lineage, termed VIb/1, within genotype VI of NDV strains of chickens, whereas a small number of isolates that originated in Croatia after 1995, grouped in a highly diverged lineage, termed VIb/2, indicating a separate host-switching event from that of VIb/1 strains. Four distinct subgroups of lineage VIb/1, Iraqi (IQ), early European (EU/ea), North American (NA) and recent European (EU/re) have emerged and circulated in the past decades.

On the origins and relationships of Newcastle disease virus vaccine strains Hertfordshire and Mukteswar, and virulent strain Herts'33.

The origins and relationships of Newcastle disease virus (NDV) vaccine strains Hertfordshire (H) and Mukteswar, and the virulent Herts'33 were studied using partial sequence analysis of the fusion protein gene. The mesogenic strain H was obtained by egg passages of a field virus isolated in England in 1933 (later known as Herts'33). Different lines of the strain Herts'33, however, divided into two distinct groups: genotype IV, and a hitherto undescribed lineage, which comprised the Weybridge line (Herts'33/56).

Genetic analysis of Newcastle disease virus strains isolated in Bosnia-Herzegovina, Croatia, Slovenia and Yugoslavia, reveals the presence of only a single genotype, V, between 1979 and 2002.

Newcastle disease (ND) epizootics in some European countries after the World War II were caused by ND virus (NDV) of multiple genotypes (IV-VIIa) occurring sequentially and/or simultaneously. This study was carried out to characterise the genetic composition of NDV strains during the outbreaks in the territory of the former Yugoslavia in order to enhance our understanding of the relationships of past epizootics in Europe. Sixty-eight NDV strains isolated between 1979 and 2002 were analysed by restriction enzyme digestion and partial sequencing of the fusion protein gene.

Occurrence of genotypes IV, V, VI and VIIa in Newcastle disease outbreaks in Germany between 1939 and 1995.

Forty-five velogenic Newcastle disease virus strains isolated in Germany between 1939 and 1995 were analysed by restriction enzyme digestion and sequencing to shed light on the relationships of past epizootics. Viruses derived from the period prior to 1970 belonged to a clade (IVea) of genotype IV comprising the earliest isolates from Europe, and could be isolated until the late seventies from poultry. Essex'70-like viruses, the prototype of genotype V, were already present at the beginning of the 1970-74 epizootic and in sporadic cases thereafter, indicating that these Newcastle disease outbreaks started in Western Europe.

The occurrence of five major Newcastle disease virus genotypes (II, IV, V, VI and VIIb) in Bulgaria between 1959 and 1996.

Partial sequence and restriction enzyme cleavage site analyses of the fusion protein gene were used to genotype 47 Newcastle disease virus strains isolated between 1959 and 1996 in Bulgaria. Viruses belonged to five major genotypes that appeared to be associated with epizootics characterized by temporal and/or geographical restrictions. Genotype IV viruses (responsible for the European branch of the first panzootic) dominated the scene up to the early 1980s, interspersed with sporadic outbreaks caused by genotype II (US strains causing pneumoencephalitis) viruses.

A longitudinal study of velogenic Newcastle disease virus genotypes isolated in Italy between 1960 and 2000.

Thirty-six representative velogenic strains of Newcastle disease virus isolated in Italy since 1960 were characterized by restriction site and partial sequence analyses of the fusion protein gene. Viruses belonging to the six known genotypes of Lomniczi et al . were found.

Pseudorabies virus expressing bovine herpesvirus 1 glycoprotein B exhibits altered neurotropism and increased neurovirulence.

Herpesvirus glycoproteins play dominant roles in the initiation of infection of target cells in culture and thus may also influence viral tropism in vivo. Whereas the relative contribution of several nonessential glycoproteins to neurovirulence and neurotropism of Pseudorabies virus (PrV), an alphaherpesvirus which causes Aujeszky's disease in pigs, has recently been uncovered in studies using viral deletion mutants, the importance of essential glycoproteins is more difficult to assess. We isolated an infectious PrV mutant, PrV-9112C2, which lacks the gene encoding the essential PrV glycoprotein B (gB) but stably carries in its genome and expresses the homologous gene of bovine herpesvirus 1 (BHV-1) (A.

Two novel genetic groups (VIIb and VIII) responsible for recent Newcastle disease outbreaks in Southern Africa, one (VIIb) of which reached Southern Europe.

34 strains of Newcastle disease virus (NDV) isolated during epizootics in the Republic of South Africa and in Mozambique between 1990 and 1995, and in Bulgaria and Turkey in 1995-1997 were identified by restriction enzyme and partial sequence analysis of the fusion (F) protein gene. The majority of isolates in southern Africa and those from Bulgaria and Turkey were placed into a novel group which has been termed VIIb. Group VIIb is part of a larger genetic cluster (VII) that also includes NDV strains from the Far East and some western European countries (VIIa).

Newcastle disease outbreaks in recent years in western Europe were caused by an old (VI) and a novel genotype (VII).

Newcastle disease virus (NDV) strains, isolated from outbreaks during epizootics between 1992 and 1996 in Western European countries, were compared by restriction enzyme cleavage site mapping of the fusion (F) protein gene between nucleotides 334 and 1682 and by sequence analysis between nucleotides 47 and 435. Both methods revealed that NDV strains responsible for these epizootics belong to two distinct genotypes. Strains derived from sporadic cases in Denmark, Sweden, Switzerland and Austria were classified into genotype VI [6], the same group which caused outbreaks in the Middle East and Greece in the late 1960's and in Hungary in the early 1980's.

Rapid identification of Newcastle disease virus vaccine strains LaSota and B-1 by restriction site analysis of their matrix gene.

A region constituting 88% of the matrix gene of Newcastle disease virus vaccine strains LaSota and B-1 was amplified by reverse transcription-polymerase chain reaction. Amplified products of LaSota and B-1 strains derived from vaccine serials of different companies were digested with restriction enzymes MboI and HinfI. Strain characteristic cleavage site maps were obtained that allowed for a reliable and rapid differentiation between strains LaSota and B-1.

Identification and grouping of Newcastle disease virus strains by restriction site analysis of a region from the F gene.

A 75% region of the F gene (between nucleotides 334 and 1682) of Newcastle disease virus (NDV) RNA was amplified by reverse transcription polymerase chain reaction (RT-PCR). PCR products were cleaved by three restriction endonucleases and the positions of thirty cleavage sites were mapped in more than 200 NDV strains. Restrictions site analysis established six major groups of NDV isolates and unique fingerprints of vaccine strains.

Mutations affecting the UL21 gene contribute to avirulence of pseudorabies virus vaccine strain Bartha.

Analysis of the live attenuated pseudorabies virus (PrV) vaccine strain Bartha indicated location of a major determinant for PrV neurovirulence within the genomic BamHI fragment 4 (B. Lomniczi et al., 1984, J.

High frequency intergenomic recombination of suid herpesvirus 1 (SHV-1, Aujeszky's disease virus).

Examples are given of observations made with field isolates of suid herpesvirus 1 (SHV-1) which indicate that intergenomic recombination is a common phenomenon associated with the virus. This was further confirmed by experimental co-infection of a pig with 2 virus strains with different, stable and easily identifiable genomic markers, followed by natural transmission to a group of contact pigs. A variety of recombinants was subsequently isolated, while none of the parental strains were re-isolated from any of the pigs.

Round table on control of Aujeszky's disease and vaccine development based on molecular biology.

A summary is given on the 4 topics which were discussed during the round table and which represent current knowledge on the molecular biology of Aujeszky's disease (pseudorabies) virus. They include a review on 1. the genome and gene products of the virus; 2.

The ability of pseudorabies virus to grow in different hosts is affected by the duplication and translocation of sequences from the left end of the genome to the UL-US junction.

Pseudorabies virus is a herpesvirus which has a class 2 genome. However, under certain growth conditions it acquires a genome with class 3-like characteristics. In these variants, the leftmost sequences of the long (L) component of the viral genome have been duplicated and translocated to the right of the L component next to the short (S) component, resulting in an L component that is bracketed by inverted repeats.