Paul Selleck

Influenza Virus A (H10N7) in Chickens and Poultry Abattoir Workers, Australia

In March 2010, an outbreak of low pathogenicity avian influenza A (H10N7) occurred on a chicken farm in Australia. After processing clinically normal birds from the farm, 7 abattoir workers reported conjunctivitis and minor upper respiratory tract symptoms. Influenza virus A subtype H10 infection was detected in 2 workers.

Reduced Sensitivity of Influenza A (H5N1) to Oseltamivir

We tested the neuraminidase drug sensitivity of clade 1 and clade 2 influenza A virus (H5N1). All viruses demonstrated similar sensitivity to zanamivir, but compared to the 2004 clade 1 viruses, the Cambodian 2005 viruses were 6-fold less sensitive and the Indonesian clade 2 viruses were up to 30-fold less sensitive to oseltamivir.

Development and Use of Fowlpox Vectored Vaccines for Avian Influenza

Abstract:  The avian influenza (AI) vaccine designated TROVAC™‐AIV H5 (TROVAC‐H5) contains a live recombinant fowlpox rec. (FP) recombinant (recFP), expressing the hemagglutinin (HA) gene of an AI H5 subtype isolate. This recombinant vaccine was granted a license in the United States for emergency use in 1998 and full registration in Mexico, Guatemala, and El Salvador where over 2 billion doses have been administered. One injection of TROVAC‐H5 protects chickens against AI‐induced mortality and morbidity for at least 20 weeks, and significantly decreases shedding after challenge with a wide panel of H5‐subtype AI strains, regardless of neuraminidase subtype. Recently, excellent protection was demonstrated against 2003 and 2004 Asian highly pathogenic H5N1 isolates. Whereas TROVAC‐H5 AI H5 efficacy was not inhibited by anti‐AI or anti‐fowlpox maternal antibodies (passive immunity), protection to AI was significantly decreased in chickens previously vaccinated or infected with FP (active immunity). Advantages of the TROVAC‐H5 vaccine over inactivated AI vaccines are: (a) single administration at 1 day of age and early onset (1 week) of protection, (b) easy monitoring of AI infection in vaccinated flocks with agar gel precipitation (AGP) and enzyme‐linked immunosorbent assay (ELISA) used as tests to differentiate infected from vaccinated animals (DIVA tests), and (c) no residue problem due to adjuvant. These features make TROVAC‐H5 an ideal AI vaccine for routine administration of day‐of‐age chicks in hatcheries. RecFP expressing HA from three lineages of H7 subtype (Eurasian, American, and Australian) were also tested for efficacy against a highly pathogenic avian influenza (HPAI) Eurasian HPAI H7N1. Only the recFP expressing the Eurasian H7 gene provided sufficient protection indicating that the breadth of protection induced by recFP is apparently restricted for H7 isolates. The fowlpox vector technology can also be used for the production of an emergency vaccine: once the HA sequence of an emerging AI virus is known, recFP can be rapidly generated. TROVAC‐H5 has recently been shown to be immunogenic in cats and could therefore also be considered for use in mammals.

Efficacy of a Fowlpox-Vectored Avian Influenza H5 Vaccine against Asian H5N1 Highly Pathogenic Avian Influenza Virus Challenge

Abstract A recombinant fowlpox-avian influenza (AI) H5 vaccine (rFP-AIV-H5) expressing the hemagglutinin of the A/turkey/Ireland/1378/83 H5N8 AI isolate has been used in Central America since 1998 to control H5N2 low pathogenicity AI. Previously, this vaccine was shown to induce full protection against a panel of H5 highly pathogenic (HP) AI isolates, including HPAI H5N1. Here, we evaluate the efficacy of rFP-AIV-H5 against escalating doses of HPAI H5N1 A/chicken/SouthKorea/ES/03 isolate and against the HPAI H5N1 A/chicken/Vietnam/0008/2004 isolate. In both studies, 1-day-old specific pathogen-free (SPF) chickens were vaccinated by subcutaneous route with rFP-AIV-H5 and challenged 3 wk later by the oronasal route. In the first study, full protection was observed up to a challenge dose of 6.5 log10 embryo infectious dose (EID50), and the 50% chicken infectious dose was estimated to be 3.1 and 8.5 log10 EID50 in the control and the rFP-AIV-H5-vaccinated group, respectively. A 2–4 log10 and >4 log10 reduction of oral and cloacal shedding was observed in rFP-AIV-H5 vaccinated birds, respectively. The rFP-AIV-H5 vaccine induced hemagglutination inhibition antibodies (5.2 log2) detectable with homologous H5N8 antigen. In the second study, rFP-AIV-H5-vaccinated chicks were fully protected against morbidity and mortality after challenge with the 2004 Vietnam isolate, whereas unvaccinated chickens died within 2 days of challenge. Shedding in cloacal swabs was detected in all unvaccinated controls but in none of the rFP-AIV-H5-vaccinated chickens. Together, these results confirm the excellent level of protection induced by rFP-AIV-H5 in SPF chickens against two recent Asian HPAI H5N1 isolates.

An outbreak of highly pathogenic avian influenza in Australia in 1997 caused by an H7N4 virus.

Abstract In November of 1997 an outbreak of highly pathogenic avian influenza occurred near the town of Tamworth, in northern New South Wales, Australia. The viruses isolated from chickens on two commercial chicken farms were identified as H7N4 viruses, with hemagglutinin cleavage site amino acid sequences of RKRKRG and intravenous pathogenicity indices of 2.52 and 2.90, respectively. A virus with an identical nucleotide sequence, but with an intravenous pathogenicity index of 1.30, was also isolated from cloacal swabs collected from asymptomatic emus kept on a third property.

Surveillance and analysis of avian influenza viruses, Australia.

TOC Summary: A lineage unique to Australia has been identified.

Rapid Detection of Highly Pathogenic Avian Influenza H5N1 Virus by TaqMan Reverse Transcriptase–Polymerase Chain Reaction

Abstract Highly pathogenic avian influenza (AI) H5N1 viruses have been spreading from Asia since late 2003. Early detection and classification are paramount for control of the disease because these viruses are lethal to birds and have caused fatalities in humans. Here, we described TaqMan reverse transcriptase-polymerase chain reaction assays for rapid detection of all AI viruses (influenza type A) and for identification of H5N1 of the Eurasian lineage. The assays were sensitive and quantitative over a 105–106 linear range, detected all of the tested AI viruses, and enabled differentiation between H5 and H7 subtypes. These tests allow definitive confirmation of an AI virus as H5 within hours, which is crucial for rapid implementation of control measures in the event of an outbreak.

Isolation of avian influenza viruses from two different transhemispheric migratory shorebird species in Australia

Summary.Shorebirds on their southerly migration from Siberia to Australia, may pass through Asian regions currently experiencing outbreaks of highly pathogenic H5N1 influenza. To test for the presence of avian influenza viruses in migratory shorebirds arriving in Australia during spring 2004, 173 cloacal swabs were collected from six species. Ten swabs were positive for influenza A, with H4N8 viruses detected in five red-necked stints and H11N9 viruses detected in five sharp-tailed sandpipers. No H5N1 viruses were detected. All isolated viruses were non-pathogenic in domestic chickens. These results further demonstrate the potential for migratory shorebirds to carry and potentially spread influenza viruses.

Antibody Titer Has Positive Predictive Value for Vaccine Protection against Challenge with Natural Antigenic-Drift Variants of H5N1 High-Pathogenicity Avian Influenza Viruses from Indonesia

ABSTRACT Vaccines are used in integrated control strategies to protect poultry against H5N1 high-pathogenicity avian influenza (HPAI). H5N1 HPAI was first reported in Indonesia in 2003, and vaccination was initiated in 2004, but reports of vaccine failures began to emerge in mid-2005. This study investigated the role of Indonesian licensed vaccines, specific vaccine seed strains, and emerging variant field viruses as causes of vaccine failures. Eleven of 14 licensed vaccines contained the manufacturers listed vaccine seed strains, but 3 vaccines contained a seed strain different from that listed on the label. Vaccines containing A/turkey/Wisconsin/1968 (WI/68), A/chicken/Mexico/28159-232/1994 (Mex/94), and A/turkey/England/N28/1973 seed strains had high serological potency in chickens (geometric mean hemagglutination inhibition [HI] titers, ≥1:169), but vaccines containing strain A/chicken/Guangdong/1/1996 generated by reverse genetics (rg; rgGD/96), A/chicken/Legok/2003 (Legok/03), A/chicken/Vietnam/C57/2004 generated by rg (rgVN/04), or A/chicken/Legok/2003 generated by rg (rgLegok/03) had lower serological potency (geometric mean HI titers, ≤1:95). In challenge studies, chickens immunized with any of the H5 avian influenza vaccines were protected against A/chicken/West Java/SMI-HAMD/2006 (SMI-HAMD/06) and were partially protected against A/chicken/Papua/TA5/2006 (Papua/06) but were not protected against A/chicken/West Java/PWT-WIJ/2006 (PWT/06). Experimental inactivated vaccines made with PWT/06 HPAI virus or rg-generated PWT/06 low-pathogenicity avian influenza (LPAI) virus seed strains protected chickens from lethal challenge, as did a combination of a commercially available live fowl poxvirus vaccine expressing the H5 influenza virus gene and inactivated Legok/03 vaccine. These studies indicate that antigenic variants did emerge in Indonesia following widespread H5 avian influenza vaccine usage, and efficacious inactivated vaccines can be developed using antigenic variant wild-type viruses or rg-generated LPAI virus seed strains containing the hemagglutinin and neuraminidase genes of wild-type viruses. IMPORTANCE H5N1 high-pathogenicity avian influenza (HPAI) virus has become endemic in Indonesian poultry, and such poultry are the source of virus for birds and mammals, including humans. Vaccination has become a part of the poultry control strategy, but vaccine failures have occurred in the field. This study identified possible causes of vaccine failure, which included the use of an unlicensed virus seed strain and induction of low levels of protective antibody because of an insufficient quantity of vaccine antigen. However, the most important cause of vaccine failure was the appearance of drift variant field viruses that partially or completely overcame commercial vaccine-induced immunity. Furthermore, experimental vaccines using inactivated wild-type virus or reverse genetics-generated vaccines containing the hemagglutinin and neuraminidase genes of wild-type drift variant field viruses were protective. These studies indicate the need for surveillance to identify drift variant viruses in the field and update licensed vaccines when such variants appear.

Novel Phlebovirus with Zoonotic Potential Isolated from Ticks, Australia

Recently discovered tick-borne phleboviruses have been associated with severe disease and death among persons in Asia and the United States. We report the discovery of a novel tick phlebovirus in Tasmania State, Australia, that is closely related to those zoonotic viruses found in Asia and North America.