miércoles, 23 de noviembre de 2016


Canine and Feline Vaccination Guidelines



The UC Davis VMTH vaccination guidelines below have been based on recently published studies and recommendations made by task forces (including the AAFP/AFM Advisory Panel on Feline Vaccines, AAHA Canine Vaccine Task Force, and the AVMA Council on Biologic and Therapeutic Agents), which include representatives from academia, private practices, governmental regulatory bodies, and industry. These groups have evaluated the benefits versus risks of the vaccines currently available on the market. Interested readers are referred to documents published by these groups for further information (see References and Resources listed at the end of this document). The document below has been generated by a group of faculty and staff at UC Davis School of Veterinary Medicine for the purposes of VMTH veterinary student education and as a reference for referring veterinarians. These are only general guidelines, as the vaccine types recommended and the frequency of vaccination vary depending on the lifestyle of the pet being vaccinated, i.e. indoor vs outdoor pets, travel plans, kennel/boarding plans, and underlying disease conditions such as immune-mediated diseases or pre-existing infections such as FIV infection. Because these factors may change over time, we recommend the vaccination plan for each individual pet be decided by the owner at routine annual examinations, following a discussion between the veterinarian and the client regarding the animal’s lifestyle in the year ahead. Guidelines for vaccination in shelter situations can be accessed at the Center for Companion Animal Health's shelter medicine website. A previous history of vaccination reactions in an individual pet will also affect recommendations for vaccination. For all vaccines given, the product, expiration date, lot number, route and location of injection is documented in the record.
It should also be noted that much research in the area of companion animal vaccinology is required to generate optimal recommendations for vaccination of dogs and cats. As further research is performed, and as new vaccines become available on the market, this document will be continuously updated and modified.

I.  Canine Vaccination Guidelines

Canine Core Vaccines
Core vaccines are recommended for all puppies and dogs with an unknown vaccination history. The diseases involved have significant morbidity and mortality and are widely distributed, and in general, vaccination results in relatively good protection from disease. These include vaccines for canine parvovirus (CPV), canine distemper virus (CDV), canine adenovirus (CAV), and rabies.
Canine Parvovirus, Distemper Virus, and Adenovirus-2 Vaccines
For initial puppy vaccination (£ 16 weeks), one dose of vaccine containing modified live virus (MLV) CPV, CDV, and CAV-2 is recommended every 3-4 weeks from 6-8 weeks of age, with the final booster being given no sooner than 16 weeks of age. For dogs older than 16 weeks of age, two doses of vaccine containing modified live virus (MLV) CPV, CDV, and CAV-2 given 3-4 weeks apart are recommended. After a booster at one year, revaccination is recommended every 3 years thereafter, ideally using a product approved for 3-year administration, unless there are special circumstances that warrant more or less frequent revaccination. Note that recommendations for killed parvovirus vaccines and recombinant CDV vaccines are different from the above. These vaccines are not currently stocked by our pharmacy or routinely used at the VMTH. We do not recommend vaccination with CAV-1 vaccines, since vaccination with CAV-2 results in immunity to CAV-1, and the use of CAV-2 vaccines results in less frequent adverse events.
Canine Rabies Virus Vaccines
In accordance with California state law, we recommend that puppies receive a single dose of killed rabies vaccine at 16 weeks or 4 months of age. Adult dogs with unknown vaccination history should also receive a single dose of killed rabies vaccine. A booster is required one year later, and thereafter, rabies vaccination should be performed every 3 years using a vaccine approved for 3-year administration.
Canine Non-Core Vaccines
Non-core vaccines are optional vaccines that should be considered in light of the exposure risk of the animal, ie. based on geographic distribution and the lifestyle of the pet. Several of the diseases involved are often self-limiting or respond readily to treatment. Vaccines considered as non-core vaccines are canine parainfluenza virus (CPiV), canine influenza virus, distemper-measles combination vaccine, Bordetella bronchiseptica,Leptospira spp., and Borrelia burgdorferi. Vaccination with these vaccines is generally less effective in protecting against disease than vaccination with the core vaccines.
Canine Parainfluenza Virus and Bordetella bronchiseptica
These are both agents associated with kennel cough in dogs. For Bordetella bronchiseptica, mucosal vaccination with live avirulent bacteria is recommended for dogs expected to board, be shown, or to enter a kennel situation within 6 months of the time of vaccination. We currently stock the intranasal vaccine containing both B. bronchiseptica and CPiV. For puppies and previously unvaccinated dogs, only one dose of this vaccine is required (recommendations differ for the parenteral, killed form of this vaccine). Most boarding kennels require that this vaccine be given within 6 months of boarding; the vaccine should be administered at least one week prior to the anticipated boarding date for maximum effect. Although some kennels require immunization every 6 months, annual booster vaccination with B. bronchiseptica vaccines is considered adequate for protection.
Canine Influenza Virus (CIV)
Canine influenza virus (H3N8) emerged in the United States in greyhounds in Florida in 2003. The virus is now enzootic in many dog populations in Colorado, Florida, Pennsylvania, New Jersey and New York. The virus causes upper respiratory signs including a cough, nasal discharge, and a low-grade fever followed by recovery. A small percentage of dogs develop more severe signs in association with hemorrhagic pneumonia. A vaccine is commercially available, which at the time of writing has a 1-year conditional licensure. Based on evidence provided by the manufacturer, the vaccine may reduce clinical signs and virus shedding in dogs infected by CIV. It may be useful for dogs traveling and intermingling with other dog populations in areas where the virus is enzootic. The performance of the vaccine and its duration of immunity in the field are unknown. At the time of writing, only a few cases of CIV infection have been documented in northern California and the infection has not been widely documented in the general dog population, so we do not recommend routine vaccination for dogs expected to board, be shown, or enter a kennel situation within northern California. Vaccination may have the potential to interfere with the results of serological testing, which in non-endemic areas are useful to assist diagnosis. The UC Davis VMTH does not stock the CIV vaccine or recommend it for use in dogs residing solely in northern California.
Canine Distemper-Measles Combination Vaccine
This vaccine has been used between 4 and 12 weeks of age to protect dogs against distemper in the face of maternal antibodies directed at CDV. Protection occurs within 72 hours of vaccination. It is indicated only for use in households/kennels/shelters where CDV is a recognized problem. Only one dose of the vaccine should be given, after which pups are boostered with the CDV vaccine to minimize the transfer of anti-measles virus maternal antibodies to pups of the next generation. The AAHA Canine Vaccination Guidelines state that ‘recent unpublished studies have shown that the recombinant CDV vaccine immunizes puppies in the face of passively acquired maternal antibodies. Therefore, the distemper-measles vaccine is no longer the preferred option’. The UC Davis VMTH does not stock these vaccines as situations requiring their use do not arise commonly in our hospital population.
Canine Leptospira Vaccines
Multiple leptospiral serovars are capable of causing disease in dogs, and minimal cross-protection is induced by each serovar. Currently available vaccines do not contain all serovars, efficacies against infection with the targeted serovar are between 50 and 75%, and duration of immunity is probably about 1 year. However, leptospirosis is not uncommon in Northern Californian dogs with exposure histories involving livestock and areas frequented by wild mammals, the disease can be fatal or have high morbidity, and also has zoonotic potential. Therefore, we suggest annual vaccination of dogs living in/visiting rural areas or areas frequented by wildlife with vaccines containing all four leptospiral serovars (grippotyphosapomonacanicola and icterohemorrhagiae), ideally before the rainy season, when disease incidence peaks. The initial vaccination should be followed by a booster 2-4 weeks later, and the first vaccine be given no earlier than 12 weeks of age. In general, leptospiral vaccines have been associated with more severe postvaccinal reactions (acute anaphylaxis) than other vaccines. Whether the recent introduction of vaccines with reduced amounts of foreign protein has reduced this problem is still unclear. Vaccination of dogs in suburban areas with minimal exposure to farm animals or forested areas is not recommended. Anecdotally, the incidence of reactions has been greatest in puppies (< 12 weeks of age, and especially < 9 weeks of age) and small-breed dogs. A careful risk-benefit analysis is recommended before considering vaccination of small breed dogs at risk of exposure to leptospires.
Canine Borrelia burgdorferi (Lyme) Vaccine
The incidence of Lyme disease in California is currently considered extremely low. Furthermore, use of the vaccine even in endemic areas (such as the east coast of the US) has been controversial because of anecdotal reports of vaccine-associated adverse events. Most infected dogs show no clinical signs, and the majority of dogs contracting Lyme disease respond to treatment with antimicrobials. Furthermore, prophylaxis may be effectively achieved by preventing exposure to the tick vector. If travel to endemic areas (ie the east coast) is anticipated, vaccination with the Lyme subunit or OspC/OspA-containing bivalent bacterin vaccine could be considered, followed by boosters at intervals in line with risk of exposure. The UC Davis VMTH does not stock the Lyme vaccine or recommend it for use in dogs residing solely in northern California.
Other Canine Vaccines
Several other canine vaccines are currently available on the market. These are vaccines for canine coronavirus, canine adenovirus-1, and rattlesnake envenomation. The reports of the AVMA and the AAHA canine vaccine task force have listed the first three vaccines as not generally recommended, because ‘the diseases are either of little clinical significance or respond readily to treatment’, evidence for efficacy of these vaccines is minimal, and they may ‘produce adverse events with limited benefit’. Currently, information regarding the efficacy of the canine rattlesnake vaccine is insufficient. The UC Davis VMTH does not stock or routinely recommend use of these vaccines.
Canine Enteric Coronavirus Vaccine
Infection with canine enteric coronavirus (CCV) alone has been associated with mild disease only, and only in dogs < 6 weeks of age. It has not been possible to reproduce the infection experimentally, unless immunosuppressive doses of glucocorticoids are administered. Serum antibodies do not correlate with resistance to infection, and duration of immunity is unknown. In mixed infections with CCV and canine parvovirus (CPV), CPV is the major pathogen. Vaccination against CPV therefore protects puppies from disease following challenge with both canine enteric coronavirus and CPV. Thus, the UC Davis VMTH does not routinely recommend vaccination against canine enteric coronavirus and the vaccine is not stocked by our pharmacy.
Canine Rattlesnake Vaccine
The canine rattlesnake vaccine comprises venom components from Crotalus atrox (western diamondback). Although a rattlesnake vaccine may be potentially useful for dogs that frequently encounter rattlesnakes, currently we are unable to recommend this vaccine because of insufficient information regarding the efficacy of the vaccine in dogs. Dogs develop neutralizing antibody titers to C. atrox venom, and may also develop antibody titers to components of other rattlesnake venoms, but research in this area is ongoing. Owners of vaccinated dogs must still seek veterinary care immediately in the event of a bite, because 1) the type of snake is often unknown; 2) antibody titers may be overwhelmed in the face of severe envenomation, and 3) an individual dog may lack sufficient protection depending on its response to the vaccine and the time elapsed since vaccination. According to the manufacturer, to date, rare vaccinated dogs have died following a bite when there were substantial delays (12-24 hours) in seeking treatment. Recommendations for booster vaccination are still under development, but it appears that adequate titers do not persist beyond one year after vaccination. Adverse reactions appear to be low and consistent with those resulting from vaccination with other products available on the market. The product license is currently conditional as efficacy and potency have not been fully demonstrated. Based on existing evidence, the UC Davis VMTH does not currently recommend routine vaccination of dogs for rattlesnake envenomation, and the vaccine is not stocked by our pharmacy.

II. Feline Vaccination Guidelines

In general, guidelines for vaccination of cats have been strongly influenced by the appearance of vaccine-associated sarcomas in cats, and in particular their epidemiologic association with feline leukemia virus vaccines and killed rabies virus vaccines. Thus, there is clear evidence for minimizing frequency of vaccination in cats. The recommendations below have been made in light of the AVMA/AAHA/AAFP/VCS task force recommendations on vaccine-associated sarcomas in cats. Risk factors for sarcomas should be discussed with cat owners at the time of examination. If a cat develops a palpable granuloma at the site of previous vaccination, the benefits vs risks of future vaccinations should be carefully considered. All vaccine-associated sarcomas should be reported to the vaccine manufacturer.
Feline Core Vaccines
The definitions of core and non-core vaccines described in the canine vaccination guidelines above also apply to the feline vaccines. The core feline vaccines are those for feline herpesvirus 1 (FHV1), feline calicivirus (FCV), feline panleukopenia virus (FPV) and rabies.
Feline Herpesvirus 1, Feline Calicivirus and Feline Panleukopenia Virus Vaccines
For initial kitten vaccination (£ 16 weeks), one dose of parenteral vaccine containing modified live virus (MLV) FHV1, FCV, and FPV is recommended every 3-4 weeks from 6-8 weeks of age, with the final booster being given no sooner than 16 weeks of age. For cats older than 16 weeks of age, two doses of vaccine containing modified live virus (MLV) FHV1, FCV, and FPV given 3-4 weeks apart are recommended. After a booster at one year, revaccination is suggested every 3 years thereafter for cats at low risk of exposure. According to recommendations of the vaccine-associated sarcoma task force, these vaccines are administered over the right shoulder. Note that recommendations for killed and intranasal FHV1 and FCV vaccines are different from the above. Killed and intranasal varieties of these vaccines are not routinely used at the VMTH. The use of FPV MLV vaccines should be avoided in pregnant queens and kittens less than one month of age.
Feline Rabies Virus Vaccines
Cats are important in the epidemiology of rabies in the US. In general we recommend that kittens receive a single dose of killed or recombinant rabies vaccine at 12-16 weeks of age. Adult cats with unknown vaccination history should also receive a single dose of killed or recombinant rabies vaccine. For the recombinant vaccines, boosters are recommended at yearly intervals. We currently stock and suggest the use of the recombinant rabies vaccine, because there is some evidence that it is associated with a decreased risk of sarcoma formation (Srivastav et al, 2012). For the killed rabies vaccines, a booster is required at one year, and thereafter, rabies vaccination should be performed every 3 years using a vaccine approved for 3-year administration. According to recommendations of the vaccine-associated sarcoma task force, rabies vaccines are administered subcutaneously as distally as possible in the right rear limb.
Feline Non-Core Vaccines
Optional or non-core vaccines for cats consist of the vaccines for feline leukemia virus (FeLV), feline immunodeficiency virus, virulent FCV, Chlamydia felis, and Bordetella bronchiseptica.
Feline Leukemia Virus Vaccine
A number of FeLV vaccines are available on the market. The whole inactivated viral vaccines have recently been shown to be highly efficacious based on the results of molecular detection methods for FeLV, even producing sterilizing immunity, although this was not found to be the case for a inactivated mixed subunit vaccine (Torres et al, 2009). We recommend vaccination of FeLV-negative cats allowed to go outdoors or cats having direct contact with other cats of unknown FeLV status. Vaccination is most likely to be useful in kittens and young adult cats, because acquired resistance to infection develops beyond 16 weeks of age. As of 2006, the AAFP recommends primary vaccination of all kittens for FeLV, but the decision to administer booster vaccines is based on risk assessment. Vaccination is not recommended for FeLV-positive cats and indoor cats with no likelihood of exposure to FeLV.
Because of concerns relating to sarcoma formation following administration of killed, adjuvanted vaccines, we suggest the use of the recombinant FeLV vaccine, as there is some evidence that recombinant vaccines are associated with a decreased risk of sarcoma formation (Srivastav et al, 2012). Because we have experienced problems that relate to injection site pain with the parenteral recombinant FeLV vaccine, we are currently using an inactivated FeLV vaccine that has demonstrated efficacy using molecular studies (Torres et al, 2009).
Initially, two doses of FeLV vaccine are given at 2-4 week intervals, after which annual boosters (recombinant vaccine) or 3-yearly boosters (inactivated vaccine) are recommended depending on risk. According to recommendations of the vaccine-associated sarcoma task force, parenteral FeLV vaccines are administered subcutaneously as distally as possible in the left rear limb.
Feline Immunodeficiency Virus Vaccine
The FIV vaccine is an inactivated, adjuvented dual subtype vaccine that was released in July 2002. Unfortunately, vaccination of FIV-negative cats renders currently available serologic tests (ELISA and Western blot) positive for at least a year following vaccination, and polymerase chain reaction (PCR)-based tests do not reliably identify cats with natural infection. Previous vaccination does not prevent infection, and the significance of a positive test result in a vaccinated cat cannot be assessed. Questions remain regarding the vaccine’s ability to protect against all of the FIV subtypes and strains to which cats might be exposed. Therefore, the decision regarding whether to use this vaccine is not straightforward, and the risks and benefits of the use of this vaccine should be carefully discussed with owners prior to using the vaccine in cats at risk of exposure. The UC Davis VMTH pharmacy does not stock this vaccine, and its routine use in indoor cats is not recommended.
Virulent Calicivirus Vaccine
The virulent FCV vaccine (Calicivax) is a killed, adjuvanted vaccine containing just one of many different strains of hypervirulent FCV known to cause severe systemic disease, including facial or limb edema, cutaneous ulceration, hepatocellular dysfunction, and high mortality. The disease is relatively rare, but has often involved otherwise healthy, adult cats that have been vaccinated with core vaccines containing FCV. In general, outbreaks have been self-limiting with no spread to the wider cat community. Although the virulent FCV vaccine has protected against challenge with the same FCV strain present in the vaccine, no field studies have yet been performed to determine whether it protects against other virulent strains. Given that the degree of serologic cross-reactivity between these strains is low, cross-protection does not seem very likely. Currently we do not recommend or stock this vaccine because 1) it is an adjuvanted vaccine that may increase risk of sarcoma formation; 2) the disease is rare and spread tends to be self-limiting; and 3) the degree of cross-protection between the strain included in the vaccine and other virulent FCV strains is unknown. For more information on this disease, the reader is referred to the Center for Companion Animal Health's Shelter Medicine document.
Feline Chlamydia felis Vaccine
Chlamydia felis causes conjunctivitis in cats that generally responds readily to antimicrobial treatment. Immunity induced by vaccination is probably of short duration and the vaccine provides only incomplete protection. The use of this vaccine could be considered for cats entering a population of cats where infection is known to be endemic. However, the vaccine has been associated with adverse reactions in 3% of vaccinated cats, and we do not recommend routine vaccination of low-risk cats with this vaccine. The C. felis vaccine is therefore not stocked by the VMTH pharmacy.
Feline Bordetella bronchiseptica Vaccine
This is a modified live intranasal vaccine. Bordetella bronchiseptica is primarily a problem of very young kittens, where it can cause severe lower respiratory tract disease. It appears to be uncommon in adult cats and pet cats in general. For these reasons, the UC Davis VMTH does not recommend routine vaccination of pet cats for Bordetella bronchiseptica. The vaccine could be considered for young cats at high risk of exposure in large, multiple cat environments. The UC Davis VMTH pharmacy does not stock this vaccine.

Other Feline Vaccines

The feline infectious peritonitis (FIP) vaccine has been listed as ‘Not Generally Recommended’ by the AAFP.
Feline Infectious Peritonitis Vaccine
The FIP vaccine is an intranasal modified live virus product. The efficacy of this vaccine is controversial, and duration of immunity may be short, although the vaccine appears to be safe. Although exposure to feline coronaviruses in cat populations is high, the incidence of FIP is very low, especially in single-cat households (where it is 1 in 5000). Most cats in cattery situations where FIP is a problem become infected with coronaviruses prior to 16 weeks of age, which is the age at which vaccination is first recommended. Vaccination could be considered for seronegative cats entering a cattery where FIP is common. We do not routinely recommend vaccinating household cats with the FIP vaccine, and the vaccine is not stocked by our pharmacy.


Day MJ, Horzinek MC, Schultz RD. 2007. Guidelines for the Vaccination of Dogs and Cats. Compiled by the Vaccination Guidelines Group of the World Small Animal Veterinary Association. J Small Anim Pract. 48(9): 528-541
Elston T and Rodan I. 1998. Feline Vaccination Guidelines. Compend Contin Educ Small Anim Practit. 20(8):936-941
Klingborg DJ, Hustead DR, Curry-Galvin EA et al 2002. AVMA Council on Biologic and Therapeutic Agents' report on cat and dog vaccines.  J Am Vet Med Assoc.  221(10):1401-1407
Klingborg DJ, Hustead DR, Curry-Galvin EA et al 2001. AVMA's Principles of Vaccination.  J Am Vet Med Assoc.  219:  575-576 
Paul MA, Appel M, Barrett R et al. 2003. Report of the American Animal Hospital Association (AAHA) Canine Vaccine Task Force: Executive Summary and 2003 Canine Vaccine Guidelines and Recommendations. J Am Anim Hosp Assoc. 39(2):119-131 (also http://www.aahanet.org  via the AVMA Login  (green))
Srivastav A, Kass PH, McGill LD, et al. Comparative vaccine-specific and other injectable-specific risks of injection-site sarcomas in cats. J Am Vet Med Assoc 2012;241:595-602.
Torres AN, O’Halloran KP, Larson LJ, et al. 2009. Feline leukemia virus immunity induced by whole inactivated vaccination. Vet Immunol Immunopathol. Epub ahead of print. Doi:10.1016/j.vetimm.2009.10.017
The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel Report. J Am Vet Med Assoc. 229: 1405-1441 (also http://www.aafponline.org/resources/practice_guidelines.htm)
American Association of Feline Practitioners: 2000 Feline Vaccination Guidelines. http://www.aafponline.org/about/guidelines_vaccine.pdf
1998 Report of the American Association of Feline Practitioners and Academy of Feline Medicine Advisory Panel on Feline Vaccines. 1998. J Am Vet Med Assoc. 212:227-241
What You Should Know About Vaccination: a client brochure that emphasizes the importance of vaccines while explaining the factors veterinarians consider when making customized vaccine recommendations. 
You will need to search the AVMA site to find the brochures. https://www.avma.org/Pages/home.aspx
Wilson S, Greenslade J, Saunders G, et al. Difficulties in demonstrating long term immunity in FeLV vaccinated cats due to increasing age-related resistance to infection. BMC Vet Res 2012;8:125.
Wallis DM and Wallis JL. 2005. Rattlesnake Vaccine to Prevent Envenomation Toxicity in Dogs. Proceedings of the 77th
Annual Western Veterinary Conference, Las Vegas, NV.

martes, 22 de noviembre de 2016

Avian Influenza Virus H5 Strain with North American and Eurasian Lineage Genes in an Antarctic Penguin. Barriga et al 2016

Avian Influenza Virus H5 Strain with North American and Eurasian Lineage Genes in an Antarctic Penguin.

CDC. Volume 22, Number 12—December 2016

To the Editor: Previous studies have reported avian influenza virus (AIV)–positive serum samples obtained from Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarcticus), and gentoo (Pygoscelis papua) penguins (14). Only recently was an H11N2 subtype virus isolated from Adélie penguins in Antarctica (5). We performed AIV surveillance in the Antarctic Peninsula to identify the strains currently circulating in different penguins species in this area.
During 2015–2016, we sampled penguin colonies from 9 locations on the Antarctic Peninsula. We collected 138 blood samples from Adélie penguins at Ardley Island (62°13′S, 58°56′W), Arctowski Base (62°9′S, 58°28′W), and Bernardo O’Higgins Base (63°19′S, 57°53′W) and identified 5 serum samples positive for influenza. We also collected 513 cloacal swabs from Adélie, chinstrap (Technical Appendix[PDF - 621 KB - 3 pages]Figure 1, panel A), and gentoo penguins from Mikkelsen Harbor (63°54′S, 60°47′W), Dorian Bay and Port Lockroy (64°48′S, 63°30′W), Pleneau Island (65°06′S, 64°04′W), Brown Base (64°53′S, 62°52′W), Orne Harbor (64°37′S, 62°32′W), and Aitcho Island (62°23′S, 59°46′W) during January–March of 2 consecutive seasons (2015 and 2016; Technical Appendix[PDF - 621 KB - 3 pages]Figure 1, panel B). Quantitative reverse transcription PCR (RT-PCR) analysis of the matrix segment (6) identified 21 positive AIV samples from penguins (8 chinstrap, 13 gentoo) on Aitcho Island, demonstrating the presence of AIV in 2 additional penguin species in a new location in Antarctica.
Using multisegment RT-PCR performed with influenza-specific universal primers, we amplified all 8 virus segments from a chinstrap penguin specimen, which yielded cDNA products suitable for next-generation sequencing with a HiSeq 2500 System (Illumina, San Diego, CA, USA). This virus was subtyped as an H5N5 and named A/chinstrap_penguin/Antarctica/B04/2015 (H5N5). Analysis of its cleavage site confirmed this was a typical low pathogenicity AIV (LPAIV) containing cleavage motif PQRETRGLF (7).
To trace the origin of this H5N5 virus, we performed phylogenetic analyses of its hemagglutinin and neuraminidase genes (Figure, panels A, B; Technical Appendix[PDF - 621 KB - 3 pages]Figures 2, 3). The hemagglutinin gene was placed into a clade within the H5 American LPAIV lineage, clustering with AIVs isolated from ducks in the United States during 2007–2014 and blue-winged teals from Guatemala in 2010 (Technical Appendix[PDF - 621 KB - 3 pages]Figure 2). This finding suggests a possible introduction of this H5 AIV into Antarctica via the Pacific or the Mississippi–American flyways, although we cannot rule out that this H5 strain is endemic to other South America locations.
Thumbnail of Low pathogenicity avian influenza virus (AIV) (H5N5) found in Antarctic penguin. A) Phylogenetic analysis of the HA gene showing its relationship to H5 low pathogenicity North American lineage viruses. B) Phylogenic analysis of the NA gene showing its relationship to N5 viruses from Eurasia. Antarctic strains: red lines, stars; Eurasian strains: green lines, squares; North American strains: dark blue lines, circles; South American strains: light blue lines, diamonds. Sequences were
Figure. Low pathogenicity avian influenza virus (AIV) (H5N5) found in Antarctic penguin. A) Phylogenetic analysis of the HA gene showing its relationship to H5 low pathogenicity North American lineage viruses. B) Phylogenic...
The timing of arrival of migratory birds that breed in Antarctica (e.g., skua, shags, petrel, and gulls) overlaps with that of the penguins as they return to colonies for breeding and nesting during the summer in the Southern Hemisphere. These birds share a habitat, enabling close contact (5,8) and introducing the possibility of AIV spillover from flying birds to penguins. The chinstrap penguin H5 strain also clustered near the H5 strain isolated in 2008 from a kelp gull (Larus dominicanus) in Chile (9), indicating a potential route of transmission and introduction of AIV into Antarctic penguins (Figure, panel A). Kelp gull colonies are found in the Antarctic, the sub-Antarctic territory, and along the coastline of Chile and Argentina. Hence, gulls and other intermediate vector hosts, such as the south polar skua (Stercorarius maccormicki), might represent natural reservoirs that play a role in the introduction and maintenance of AIVs into Antarctica.
The chinstrap penguin neuraminidase segment clustered within a Eurasian N5 clade that includes sequences from 2001–2010 (Figure, panel B; Technical Appendix[PDF - 621 KB - 3 pages]Figure 3). The closest sequences were isolated from wild ducks from South Korea in 2008 (GenBank accession no. JX679163) and Vietnam in 2009 (GenBank accession no. AB593481). Eurasian N5s have sporadically been found in ruddy turnstones (Arenaria interpres) and an unidentified shore bird at Delaware Bay (GenBank accession nos. CY144466.1, CY144458.1, and CY102738.1). This finding suggests a plausible entryway of this gene into Antarctica from South America through the Atlantic or Pacific-American flyway, which are common routes used by shore birds, such as the ruddy turnstone, white-rumped sandpiper (Calidris fuscicollis), and red knot (Calidris canutus) (10).
As previously suggested for H11N2 viruses from Antarctica, our data supports the idea that these AIVs are evolutionarily distinct from other AIVs (5). This H5N5 strain is a contemporary reassortant virus related to North American and Eurasian strains.
The positive animals we identified originated from a single location on the Antarctic Peninsula, which suggests recent introduction of this AIV H5N5 in the colonies sampled. Antarctica is refuge for most penguin colonies, including the near-threatened emperor penguins. Previous reports suggested that AIV could have caused Adélie penguin chick death (3). Four positive samples (including the sequenced virus) were obtained from juvenile chinstrap penguins that were weak, depressed, and possibly ill (i.e., they had ruffled feathers, lethargy, and impaired movement). Thus, additional studies are warranted to assess the health and conservation status of resident bird species and potential pathologic effects of AIV.
These data provide novel insights on the ecology of AIV in Antarctica. Our findings also highlight the need for increased surveillance to understand virus diversity on this continent and its potential contribution to the genetic constellation of AIV in the Americas.
Gonzalo P. Barriga, Dusan Boric-Bargetto, Marcelo Cortez San Martin, Víctor Neira, Harm van Bakel, Michele Thompsom, Rodrigo Tapia, Daniela Toro-Ascuy, Lucila Moreno, Yesseny Vasquez, Michel Sallaberry, Fernando Torres-Pérez, Daniel González-Acuña, and Rafael A. MedinaComments to Author 
Author affiliations: Pontificia Universidad Católica de Chile, Santiago, Chile (G.P. Barriga, R.A. Medina)Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile (D. Boric-Bargetto, F. Torres-Pérez)Universidad de Santiago, Santiago (M. Cortez-San Martin, D. Toro-Ascuy, Y. Vasquez)Universidad de Chile, Santiago (V. Neira, R. Tapia, M. Sallaberry)Icahn School of Medicine at Mount Sinai, New York, New York, USA (H. van Bakel, R.A. Medina)Universidad de Concepción, Concepción, Chile (M. Thompsom, L. Moreno, D. González-Acuña)Millennium Institute on Immunology and Immunotherapy, Santiago (R.A. Medina)


We are grateful to K. Tapia, who was an excellent and invaluable technical assistance during the course of this study. We also thank the Instituto Antartico Chileno (INACH) staff for all their support during the expeditions to Antarctica.
This study was partly funded by the Center for Research in Influenza Pathogenesis (CRIP), a National Institute of Allergy and Infectious Diseases–funded Center of Excellence in Influenza Research and Surveillance (CEIRS), contract number HHSN272201400008C to R.A.M., and by the Programa de Investigación Asociativa from the Comisión Nacional de Investigación Científica y Tecnológica, project CONICYT-PIA Anillo1408 to R.A.M., F.T.P., and V.N. D.G.-A. is supported by grant RT_12-13, and M.C.-S.M. is supported by the grant RT_08-13, both awarded from INACH. G.P.B is supported by the Fondo Nacional de Desarrollo Científica y Techológica (FONDECYT) de Postdoctorado 3150564 from CONICYT, and D. B.-B. is supported by Vicerrectoría de Investigación y Estudios Avanzados-Pontificia Universidad Católica de Valparaíso.


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