Serotype Diversity and Reassortment between Human and Animal Rotavirus Strains: Implications for Rotavirus Vaccine Programs

Abstract

The development of rotavirus vaccines that are based on heterotypic or serotype-specific immunity has prompted many countries to establish programs to assess the disease burden associated with rotavirus infection and the distribution of rotavirus strains. Strain surveillance helps to determine whether the most prevalent local strains are likely to be covered by the serotype antigens found in current vaccines. After introduction of a vaccine, this surveillance could detect which strains might not be covered by the vaccine. Almost 2 decades ago, studies demonstrated that 4 globally common rotavirus serotypes (G1-G4) represent >90% of the rotavirus strains in circulation. Subsequently, these 4 serotypes were used in the development of reassortant vaccines predicated on serotype-specific immunity. More recently, the application of reverse-transcription polymerase chain reaction genotyping, nucleotide sequencing, and antigenic characterization methods has confirmed the importance of the 4 globally common types, but a much greater strain diversity has also been identified (we now recognize strains with at least 42 P-G combinations). These studies also identified globally (G9) or regionally (G5, G8, and P2A[6]) common serotype antigens not covered by the reassortant vaccines that have undergone efficacy trials. The enormous diversity and capacity of human rotaviruses for change suggest that rotavirus vaccines must provide good heterotypic protection to be optimally effective.

Molecular epidemiology of rotaviruses in Bulgaria: annual shift of the predominant genotype

“…Among these, only 11 G serotypes/genotypes and 12 P serotypes and 15 P genotypes have been found in humans [7][8][9]. Although the ability of rotavirus genes to segregate independently upon dual infection could, in theory, lead to 132 G-P combinations, five G and P combinations, G1P [8], G2P [4], G3P [8], G4P [8], and G9P [8], are epidemiologically important in human infections [10,11]. However, geographical and temporal differences exist in the distribution of G and P types and their combinations: P [6] in association with G1, G2, G3, and G9 and G8 in combination with P [8] and P [6] have been shown to be the second most detected P and G type in India and some parts of the African continent, respectively [11][12][13][14][15][16].…”

“…However, geographical and temporal differences exist in the distribution of G and P types and their combinations: P [6] in association with G1, G2, G3, and G9 and G8 in combination with P [8] and P [6] have been shown to be the second most detected P and G type in India and some parts of the African continent, respectively [11][12][13][14][15][16]. Recent studies have reported the emergence of uncommon G or P types (G5, G6, G10, G11, G12, P [3], P [7], P [9], P [11], and many more) in different countries [10,11,[17][18][19][20][21][22]. These uncommon rotavirus G/P genotypes emerge in humans through zoonotic transmission, and reassortment with common human rotavirus strains can potentially lead to the emergence of a pandemic strain [23].…”

Human, porcine and bovine rotaviruses in Slovenia: evidence of interspecies transmission and genome reassortment

“…Moreover, specific genotypes have been found in humans and in some animal species. Some of these show high levels of nucleotide and amino acid homology, suggesting interspecies transmission of rotaviruses (Gentsch et al, 2005).…”

“…Reassortment was detected within rotaviruses infecting one host species and also in rotaviruses detected in different hosts. Reassortment events result in new rotavirus strains with variable antigenic properties (Gentsch et al, 2005;Matthijnssens et al, 2006a). The introduction of a new human-animal reassortant rotavirus strain into the human population could have a huge impact on the spread of rotavirus disease and also on prevention measures.…”

Group A rotavirus genotypes and the ongoing Brazilian experience: a review

“…Up to now, at least 19 G genotypes and 27 P genotypes have been described . Theoretically, many G/P combinations are possible within the binary system utilized to classify RV-A genotypes; however, the G1P[8], G2P [4], G3P[8], G4P[8] and G9P[8] combinations are the most commonly identified genotypes worldwide (Castello et al 2004, Gentsch et al 2005, Santos & Hoshino 2005a.…”