Serosurvey against H5 and H7 avian influenza viruses in Italian poultry workers

Highly pathogenic (HP) and low pathogenic (LP) avian influenza viruses (AIVs) belonging to H5 and H7 subtypes have been found to be associated with human infection as the result of direct transmission from infected poultry. Human infections by AIVs can cause mild or subclinical disease, and serosurveys are believed to represent an important tool to identify risk of zoonotic transmission. Therefore, we sought to examine Italian poultry workers exposed during LPAI and HPAI outbreaks with the aim of assessing serologic evidence of infection with H5 and H7 AIVs. From December 2008 to June 2010 serum samples were collected from 188 poultry workers and 379 nonexposed controls in Northern Italy. The hemagglutination inhibition (HI) assay using horse red blood cells (RBCs) and a microneutralization (MN)-enzyme-linked immunosorbent assay test were used to analyze human sera for antibodies against the following H5 and H7 LPAI viruses: A/Dk/It/4445/07(H5N2); A/Ty/It/2369/09(H5N7); A/Ty/It/218-193/ 10; A/Ck/It/3775/99(H7N1); A/Ty/It/214845/03(H7N3); and A/Dk/It/332145/09(H7N3). Since previous studies identified low antibody titer to AIVs in people exposed to infected poultry, a cutoff titer of > or = 1:10 was chosen for both serologic assays. Only HI-positive results confirmed by MN assay were considered positive for presence of specific antibodies. The Fisher exact test was used to analyze differences in seroprevalence between poultry workers and control groups, with the significance level set at P < 0.05. MN results showed a proportion of H7-seropositive poultry workers (6/188, i.e., 3.2%), significantly higher than that of controls (0/379), whereas no MN-positive result was obtained against three H5 LPAI subtypes recently identified in Italy. In conclusion, the survey indicated that assessing seroprevalence can be an important tool in risk assessment and health,surveillance of poultry workers.

Pandemic influenza A/H1N1 virus in a swine farm house in Sicily, Italy

This report describes a pandemic A/H1N1 (H1N1 pdm) virus outbreak occurred in December, 2009 in a swine farm used as research facility (Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione) for preclinical studies, located in Sicily, Italy. All the 13 pigs of the farm, showed cough, fever, inappetence and weakness. At the same time, an unvaccinated worker of the stabling showed influenza-like symptoms. RNAv extracted from two swabs collected from infected pigs resulted positive by Real Time RT-PCR for Influenza A virus. Furthermore, after growth on embryonated eggs, viral isolates were identified by Real Time RT-PCR specific for H1N1 pdm virus and characterized antigenically. Sequencing of the whole genome was also performed. All sera taken from animals and from the worker were tested by a competitive influenza A ELISA and by the haemoagglutination inhibition test. Serological findings confirmed the circulation of influenza virus H1N1 pdm in pigs and the presence of specific antibodies against H1N1 pdm in human serum. The results of this study seem to support a H1N1 pdm transmission from man to animals showing the importance of serological and virological investigation to control the pig farms and the importance of close cooperation between the different authorities like veterinarian and human public.

Canine coronavirus induces apoptosis in cultured cells

Canine coronavirus (CCoV) is widespread in dogs in several countries and causes mild enteric illness evolving to severe enteritis in young pups.

In in vitro cultures canine coronaviruses generally induce extensive cell death, however nature of the events leading to cell death remains largely unknown.

We analysed the induction of cytopathic effect by CCoV in a canine fibrosarcoma cell line (A-72) in order to characterize the apoptotic effect in homologous cell system.

Following CCoV infection A-72 cell line, which is permissive to CCoV, showed reduced growth rate, as detected by MTT assay, a standard colorimetric assay for measuring cellular proliferation, and underwent to apoptotic death. Starting from 24 h after CCoV infection, cells morphology appeared dramatically changed, with cells rounding and detachment from culture surface. Morphologic and biochemical features of apoptosis, such as blebbing of the plasma membrane, translocation of phosphatidilserine to cell surface and annexin V positive staining, nuclear fragmentation, apoptotic bodies formation and DNA laddering, were detected in CCoV-infected cells. Propidium iodide staining of infected culture indicated the appearance of hypodiploid DNA peak corresponding to apoptotic cell population. Commonly to other animal coronavirus infection caspase-3 is likely to contribute to the execution phase of apoptosis induced by CCoV in A-72 cells since we found activation of enzymatic activity as well as procaspase-3 activating cleavage. Apoptotic death of infected cells is detrimental as it causes cell and tissue destruction as well as inflammatory responses. Therefore in the case of CCoV associated gastroenteritis, apoptosis of epithelial mucosa cells may be responsible for pathology induced by CCoV infection.

Molecular Characterization of Low Pathogenicity H7N3 Avian Influenza Viruses Isolated in Italy

The complete coding regions of the surface glycoproteins, nucleoprotein (NP), polymerase 2 (PB2), and matrix (M) of A/turkey/214845/02 and A/turkey/220158/99 (H7N3) low pathogenicity avian influenza (LPAI) viruses isolated in October 2002 in Italy were amplified and sequenced to determine the epidemiologic relationships with an A/turkey/Italy/4603/99 (H7N1/4603/99) LPAI virus isolated during the 1999-2001 epizootic in Italy. The hemagglutinin (HA) of H7N3 viruses showed 97.8% nucleotide similarity with A/turkey/Italy/4603/99 (H7N1), and NP, M, and PB2 gene similarities were 93.6%, 98.2%, and 96.2%, respectively. Phylogenetic analyses of HA, PB2, and M genes showed that H7N3 and H7N1 viruses were closely related. Sequence analysis revealed a 23 amino acid deletion in the stalk of the neuraminidase of H7N3 viruses and a unique deletion of amino acid glycine in position 17 in the NP gene of H7N1 virus.

Influenza surveillance in birds in Italian wetlands (1992–1998): is there a host restricted circulation of influenza viruses in sympatric ducks and coots?

We report the results of a 6-year serological and virological monitoring performed in ducks and coots in Italy, in order to assess the degree of influenza A virus circulation in these birds during wintering. A total of 1039 sera collected from 1992 to 1998 was screened by a double antibody sandwich blocking ELISA (NP-ELISA): seroprevalence of antibodies to influenza A viruses was significantly higher in ducks compared to coots (52.2% vs. 7.1%, respectively). The hemagglutination-inhibition (HI) assay, performed on NP-ELISA positive sera, showed that 16.9% of these duck sera and 33.3% of these coot sera had antibodies to at least one influenza virus HA subtype: ducks showed HI antibodies against most of the HA subtypes, except for the H3, H4, H7, and H12; coots were seropositive to the H3 and H10 subtypes, only. From 1993 to 1998, 22 virus strains were obtained from 802 cloacal swabs, with an overall virus isolation frequency of 2.7%. Viruses belonging to the H1N1 subtype were by far the most commonly circulating strains (18/22) and were isolated mainly from ducks (17/18). The remaining viruses were representative of the H10N8, H5N2 and H3N8 subtypes. Our data indicate some differences between influenza A virus circulation in sympatric ducks and coots and a significant antigenic diversity between some reference strains and viruses recently isolated in Italy.

Circulation of influenza viruses in wild waterfowl wintering in Italy during the 1993-99 period: evidence of virus shedding and seroconversion in wild ducks

The mechanisms of perpetuation of influenza A viruses in aquatic birds, their main reservoir in nature, have not yet been completely clarified. One hypothesis is that they continue to circulate in waterfowl throughout the year, even though virus isolations during the winter months are rare. We analyzed influenza virus circulation in wild ducks in Italy during six winter seasons (1993-99), using virus isolations and serological analyses. It was apparent that influenza A viruses were constantly circulating in wild birds during all the seasons considered. Moreover, seroconversion rates (obtained from ducks recaptured during the same season) suggest a frequency of influenza infections higher than expected on the basis of the virus isolation rates.

Standardization of an Inactivated H7N1 Avian Influenza Vaccine and Efficacy Against A/Chicken/Italy/13474/99 High-Pathogenicity Virus Infection

The minimum requirements for assessing the immunogenicity of an experimental avian influenza (AI) vaccine prepared from inactivated A/Turkey/Italy/2676/99 (H7N1) low-pathogenicity (LP) AI (LPAI) virus were determined in chickens of different ages. A correlation between the amount of hemagglutinin (HA) per dose of vaccine and the protection against clinical signs of disease and infection by A/Chicken/Italy/13474/99 highly pathogenic (HP) AI (HPAI) virus was established. Depending on the vaccination schedule, one or two administrations of 0.5 microg of hemagglutinin protected chickens against clinical signs and death and completely prevented virus shedding from birds challenged at different times after vaccination.

Recent developments in avian influenza research: epidemiology and immunoprophylaxis

Influenza A viruses have been isolated from humans, from several other mammalian species and a wide variety of avian species, among which, wild aquatic birds represent the natural hosts of influenza viruses. The majority of the possible combinations of the 15 haemagglutinin (HA) and nine neuraminidase (NA) subtypes recognized have been identified in isolates from domestic and wild birds. Infection of birds can cause a wide range of clinical signs, which may vary according to the host, the virus strain, the host's immune status, the presence of any secondary exacerbating microorganisms and environmental factors. Most infections are inapparent, especially in waterfowl and other wild birds. In contrast, infections caused by viruses of H5 and H7 subtypes can be responsible for devastating epidemics in poultry. Despite the warnings to the poultry industry about these viruses, in 1997 an avian H5N1 influenza virus was directly transmitted from birds to humans in Hong Kong and resulted in 18 confirmed infections, thus strengthening the pandemic threat posed by avian influenza (AI). Indeed, reassortant viruses, harbouring a combination of avian and human viral genomes, have been responsible for major pandemics of human influenza. These considerations warrant the need to continue and broaden efforts in the surveillance of AI. Control programmes have varied from no intervention, as in the case of the occurrence of low pathogenic (LP) AI (LPAI) viruses, to extreme, expensive total quarantine-slaughter programmes carried out to eradicate highly pathogenic (HP) AI (HPAI) viruses. The adoption of a vaccination policy, targeted either to control or to prevent infection in poultry, is generally banned or discouraged. Nevertheless, the need to boost eradication efforts in order to limit further spread of infection and avoid heavy economic losses, and advances in modern vaccine technologies, have prompted a re-evaluation of the potential use of vaccination in poultry as an additional tool in comprehensive disease control strategies. This review presents a synthesis of the most recent research on AI that has contributed to a better understanding of the ecology of the virus and to the development of safe and efficacious vaccines for poultry.

Determination of bovine rotavirus G and P serotypes in italy by PCR

Determination of the G and P serotypes of group A bovine rotaviruses from 149 samples of feces or intestinal contents collected from calves showing clinical signs of neonatal diarrhea was performed by a nested reverse transcription-PCR typing assay. The G6 serotype was the most prevalent, accounting for viruses in 55.7% of the samples; viruses of the G10 and G8 serotypes were found in 34.9 and 4.7% of the samples, respectively. The virus in one sample (0.7%) was not classified due to concomitant infection with G6 and G8 strains, whereas viruses in six samples (4.0%) could not be characterized with any of the three G serotype-specific primers selected for the present study. When examined for their P-serotype specificities, viruses in 55 and 42.3% of the samples were characterized as P[11] and P[5], respectively, no P[1] serotype was identified, and viruses in 2.7% of the samples could not be classified due to multiple reactivity with both P[5]- and P[11]-specific primers. Various combinations of G and P serotypes were observed, the most frequent being G6,P[5] (38.3%), G10,P[11] (31.5%), and G6,P[11] (15.4%). The results of the present study, while contributing to a better understanding of the epidemiology of bovine rotaviruses in Italy, address the relevance of serotype specificity with regard to the constancy of the quality of bovine rotavirus vaccines under different field conditions.

Comparative evaluation of in vitro and in vivo assays for the detection of avian infectious bronchitis virus as a contaminant of live poultry vaccines

A reverse transcriptase polymerase chain reaction (RT-PCR( assay specific for identifying avian infectious bronchitis virus (IBV) in poultry vaccines, and the serological response to IBV induced by the inoculation of chicks with a Newcastle disease vaccine spiked with the Massachusetts strain of IBV, were compared for their ability to detect IBV as a contaminant of avian vaccines. The sensitivity of the IBV-RT-PCR assay provided results which were at least equivalent to the biological effect produced by the inoculation of chicks, allowing this assay to be considered a valid alternative to animal testing in the quality control of avian immunologicals. This procedure can easily be adapted to detect a number of contaminants for which the in vivo test still represents the only available method of detection.

Rapid diagnosis of avian infectious bronchitis virus by the polymerase chain reaction

A simple, sensitive and specific polymerase chain reaction (PCR) procedure was developed in order to detect infectious bronchitis virus (IBV) directly in tissue samples. Viral RNA was extracted from allantoic fluids and cell cultures infected experimentally with different strains of IBV and from tissues of naturally infected birds. Viral RNA was then amplified and identified by a nested RT-PCR assay using two sets of primers flanking a well-conserved region of the nucleocapsid gene. The selected IBV nucleocapsid sequence was detected successfully by simple direct electrophoresis of amplified material.

Characterization of Newcastle disease viruses isolated from pigeons in Italy

The authors report the results of characterization studies of three strains of Newcastle disease virus (NDV) (two isolated from pigeons and one from chickens). The plaque cloning of the viruses, showed that each NDV strain consists of different clones of genetically mixed viral populations. The pigeon NDV isolates were classified as lentogenic using mean death time (MDT) determination; while the intracerebral pathogenicity index (ICPI) was the same as the velogenic NDV strain.

Isolation in Italy of feline immunodeficiency virus (FIV)

The Authors report the isolation in Italy of Feline Immunodeficiency Virus (FIV) from a cat inoculated with whole blood from a naturally FIV infected cat. The virus was isolated in feline circulating leucocytes cultured in RPMI medium and stimulated with concanavalin-A and recombinant human interleukin-2. The infected cultures showed a characteristic cytopathic effect (ballooning degeneration, giant cell formation, cell death) and a specific fuorescence using FIV-positive cat serum and monoclonal antibodies against FIV. Furthermore, the culture supernatants contained magnesium-dependent reverse transcriptase activity.

A rapid serum neutralization test in microplates for the detection of antibodies to hog cholera virus

The fluorescent antibody serum neutralization (FASN) test for the detection of antibodies to hog cholera virus was developed utilizing 96-well and Terasaki microplates. This microtechnique, especially when performed in Terasaki plates, offers some advantage if compared with conventional FASN in coverslip cell cultures, being easier and more rapid, saving of reagents and allowing simple microscopic observation.

Antibody levels following ERA rabies vaccine in cattle

The humoral response in cattle treated with ERA strain rabies vaccine, was studied utilizing the following criteria: antibody titres determined by RFFIT, seroimmunological monitoring of experimentally vaccinated animals, a comparison of data obtained from cattle vaccinated and maintained under field conditions in the absence of anamnestic information. The average antibody responses in the field experiment are in agreement with the laboratory animal response, both showing highest levels at day 15 after vaccination; at day 30 in both groups the immune response is sensibly lower, to remain then on a constant level after day 90 and stay about 0.5 I.U./ml up to the fifteenth month.

A summary of antibody titration experiments in some animal species treated with ERA vaccine and an inactivated rabies vaccine

The results of antibody titrations in different animal species vaccinated against rabies are reported. The following points are considered: (1) antibody titration may be used to detect an immunity status in dogs, (2) equines should be vaccinated in infected areas, (3) experiments in progress are comparing ERA vaccine and an inactivated vaccine in bovines, and (4) the vaccination of fallow deer (Dama dama) and moufflons (Ovis ammon musimon) produced results suggesting an extension of the experiment with the purpose of vaccinating wild ruminants whenever possible.